Super annoying low coolant alarm going off until car warms up (earth issue??)

[Young Angus]

So my silly low coolant alarm has a problem. It's super annoying. Started happening after the first round of mechanical work and then when I took it back they added an earth somewhere and it went away. Recently after a bunch more work from a different crowd installing driving lights and UHF the noise is back.

When I start the engine the low coolant alarm does its usual beep to tell me it's working, but then until some random point when the car warms up to operating temperature it seems (bit of a guess) the low coolant alarm keeps coming back on softly...Then loudly...Then it goes up and down in volume with the indicator or it gets lower if I put my foot on the brake or turn on the lights then it gets louder again...It's driving us bonkers and it doesn't go away until I've been driving for a while, the kind of while that leads me to think it's at operating temp.

All the mechanics are still on holidays so I'd rather sort this before then if anyone has any ideas what may be happening...Any ideas?

[trout1105]

What type of low coolant alarm do you have fitted and where is the sensor/sensors fitted?

[edddo]

this^

I have a low coolant alarm in the top of the radiator near the bleed hose.
It goes off if there is a bit of air in the system after I have played with the cooling system - so In my case it indicated air in the system/low coolant - as you would expect.
How is yours set up?

[Young Angus]

I believe mine is also in the top of the radiator. This isn't just going off though, it's going completely bananas and then it shuts off. I will get a recording of it, that'll say a thousand words.

[Vern]

Mines in the same spot, i ended up putting a longer sender bolt in. Fixed

[Fausto79]

Mine does that the day after a long drive or if it has been sitting idle for a few days. Usually only keeps beeping until the engine is turned on. Once it was beeping on and off like you say and i unscrewed the bolt and dripped some coolant in. Then ran car and bled air out.

Mine is on top of thermostat housing though.

[AK83]

I was thinking about this the other day ... could this somehow be related to your Redarc DBS solenoid getting hot too?

Then I remember you said that the low coolant alarm issue only started recently .. but what about the heating up solenoid?

I remember that your coolant alarm is on the radiator fill plug.
I suppose it's a silly question but is the radiator/reservoir actually full or at the correct level? [biggrin]

[biggin]

Have you tried cleaning the sensor? A wire brush should do it.

[rick130]

I wonder of the ejector line is blocked?

Otherwise as above, pop the sender out and check.
It may have scale buildup?

[trout1105]

If your coolant alarm is constantly going off I suspect that you have a problem with the cooling system and Not the alarm itself.
You say that it self test on startup, this is Good.
The alarm doesn't activate until the engine warms up, This is telling me that the alarm is working properly.
What you are describing is consistent with there being air at the top of the coolant system when the engine heats up and this lack of coolant is setting the alarm off.
Does the level in your header tank fluctuate? Have you tried bleeding the air out of the coolant system? What New work have you had done on the engine?

[Young Angus]

The alarm actually goes silly right when I start driving and stays like that until the engine warms up....So when it warms up it turns off. It only carries on while the engine is cold.

Even after letting if cool down just a little it will fire back up again as I drive off until the engine warms up properly again.

https://www.aulro.com/afvb/images/imported/2018/01/48.jpg

That's where my sensor is but I haven't popped anything open yet to take a look.

[trout1105]

The alarm actually goes silly right when I start driving and stays like that until the engine warms up....So when it warms up it turns off. It only carries on while the engine is cold.

Even after letting if cool down just a little it will fire back up again as I drive off until the engine warms up properly again.

OK.
I am pretty certain then that your cooling system needs to be bled to remove ALL the air from it, This is very easy to do [thumbsupbig]

[AK83]

Going from this description

.... the low coolant alarm keeps coming back on softly...Then loudly...Then it goes up and down in volume with the indicator or it gets lower if I put my foot on the brake or turn on the lights then it gets louder again...It's driving us bonkers and it doesn't go away until I've been driving for a while, the kind of while that leads me to think it's at operating temp.....

... and the section where Ben describes it started or got worse with the installation of the lights and UHF ...



....
What you are describing is consistent with there being air at the top of the coolant system when the engine heats up and this lack of coolant is setting the alarm off.
....


OK.
I am pretty certain then that your cooling system needs to be bled to remove ALL the air from it ....

Seems improbable.

The mechanic added an earth between rad and front of body, and it appeared to settle for a bit then started again with the install of the lights and UHF.

While it'd make sense that a bleed may be a cause, it's less likely to be the case in this instance due to the new electrical work done.

I dunno how these devices work myself, but the advice to pull out the sensor and give it a clean is probably the best start point.

[trout1105]

While it'd make sense that a bleed may be a cause, it's less likely to be the case in this instance due to the new electrical work done.

I dunno how these devices work myself, but the advice to pull out the sensor and give it a clean is probably the best start point.

These low coolant alarms work by detecting the fluid in the cooling system NO fluid and the alarm goes off, Simples [thumbsupbig]
They are also designed to work in a corrosive environment so unless this particular alarm is several years old the sensor should be good to go.
If young angus removes the sensor when the engine is cold before startup and looks to see if there is indeed enough coolant where the sensor is fitted he can see if it is the sensor or a low coolant issue.
Anything else is just guesswork.

[AK83]

....
If young angus removes the sensor when the engine is cold before startup and looks to see if there is indeed enough coolant where the sensor is fitted he can see if it is the sensor or a low coolant issue.
Anything else is just guesswork.

The way the Tdi cooling system works is that if there isn't enough coolant in the radiator at the bung, the obvious telltale sign is a totally empty coolant reservoir(unless there is a major blockage of some type).

The coolant reservoir empties into the radiator via a small bleed sized hose, off the threeway junction, that Ben recently had renewed.
Could be a faulty threeway junction .. but what's the chances of that?

So in an ideal setup(ie. no blockages, etc) if you remove the radiator bung, coolant will continue to overflow out of the access port until the level of the reservoir drops down to the that of the radiator bung port.

If the radiator bung is removed to check coolant level or clean the sensor, there is a 99.9% likeyhood that air will get back up into the thermostat housing and the cooling system WILL need a bleed.
Bleed sequence is easy to do if you use blknight's method.

My understanding of some of these coolant level things is that they run a very small current, and the contact with the coolant completes the earth path(as water/coolant is conductive).
Considering the recent electrical items fitted, I'm more inclined to think it's an electrical issue.

eg. if the coolant alarm runs off one particular power feed, and it's sensitive to how much current/resistance is required for it to complete this power path, then if new electrical items have been tapped into the same power feed(like a UHF and or driving lights) then theres a good chance that those new items could be causing false(lower) current/resistance readings.

[BathurstTom]

Electrical issues do not disappear when a motor warms up. When the motor warms up, the thermostat opens. I'm inclined to think there is air in the system and it needs bleeding (as others have said). I have a low coolant alarm and it goes off on mine now and again due to a weeping welch plug (in the process of being replaced now).

Tom.

[Young Angus]

I probably know the least amount about things out of everybody here, but it's great reading that's for sure :)

They all sound like great points but the overwhelming consensus seems to be bleed the silly cooling system and at least rule that out. Btw it's an Engine Saver little black module under the steering wheel where those fuses are if that makes any difference.

Now how to bleed a cooling system on a 300Tdi...hmmmm

[Don 130]

I'd suggest you look carefully for a tiny leak. Perhaps a coolant hose has a pinprick. I had one in my bottom hose, under the jubilee clip, so it took months to find it. I only noticed it because I saw a crusty build-up coming through the slots in the jubilee clip band. I had exactly the same symptoms as you, and same engine, and same alarm.
i figured that the hole is not big enough to allow a great amount of coolant out, but it does allow air to be drawn in as the engine cools. The bleeder hose eventually bleeds that small amount of air out as the engine warms up and the alarm goes off. Since I've changed my bottom hose, the alarm is functioning normally.
Don't forget to check heater hoses and heater as well.
Don.

[Young Angus]

If your coolant alarm is constantly going off I suspect that you have a problem with the cooling system and Not the alarm itself.
You say that it self test on startup, this is Good.
The alarm doesn't activate until the engine warms up, This is telling me that the alarm is working properly.
What you are describing is consistent with there being air at the top of the coolant system when the engine heats up and this lack of coolant is setting the alarm off.
Does the level in your header tank fluctuate? Have you tried bleeding the air out of the coolant system? What New work have you had done on the engine?

Thought I should clarify, part of the new work I had done was the complete removal and flushing of the cooling system, radiator got shipped off to a radiator place and tested and cleaned out then brought back and re-fitted, all new radiator hoses (most of them I think) and of course new coolant top up...so part of this would have been to bleed the system so I guess that's a possibility.

It's just odd that the problem went away after they got the car back and did something to the earthing...then it came back again after more work had been done...none of which makes sense when we're talking about the much more sensible possibility that there may be a little air in the system until the thermostat opens up.

[Young Angus]

I'd suggest you look carefully for a tiny leak. Perhaps a coolant hose has a pinprick. I had one in my bottom hose, under the jubilee clip, so it took months to find it. I only noticed it because I saw a crusty build-up coming through the slots in the jubilee clip band. I had exactly the same symptoms as you, and same engine, and same alarm.
i figured that the hole is not big enough to allow a great amount of coolant out, but it does allow air to be drawn in as the engine cools. The bleeder hose eventually bleeds that small amount of air out as the engine warms up and the alarm goes off. Since I've changed my bottom hose, the alarm is functioning normally.
Don't forget to check heater hoses and heater as well.
Don.

Ahhh...That's probably worth mentioning then. Since lots of the hoses were new and also the clamps some of them, in fact most of them, needed nipping up a air bit after I drove it around for a while and things settled. One thing I noticed though was the large black coolant hose going to the water pump has been leaking a bit of coolant on top of the alternator. I thought this was just due to hose clamps needing more tightening but I didn't stop to think that they may have sucked some more air I to the system. In fact, when the mechanic first had my car back to supposedly fix the earth issue another thing he did was to pressure test and nip up the hoses...I wonder if he also bled the system and hence sorted the problem. I'm not sure if he did bleed anything but there's a small chance he did because he pressure tested it.

I can't see if there is a hole in this hose but I've tightened it up a few times now and it's still leaking a little bit :(

https://www.aulro.com/afvb/images/imported/2018/01/90.jpg

[AK83]

....

Now how to bleed a cooling system on a 300Tdi...hmmmm

I'm probably(99.9% chance) going to be home all day again tomorrow, and most likely Friday too(kids holidays week with me) if you want to come around and I can show 'ya.
Shoot me a txt beforehand tho.
Very easy to do too, now that it's sunk in how to do it properly.

We could also try to do some rudimentary electrical testing too, even tho I'm not well versed in some aspects of electrics.

[Young Angus]

I'm probably(99.9% chance) going to be home all day again tomorrow, and most likely Friday too(kids holidays week with me) if you want to come around and I can show 'ya.
Shoot me a txt beforehand tho.
Very easy to do too, now that it's sunk in how to do it properly.

We could also try to do some rudimentary electrical testing too, even tho I'm not well versed in some aspects of electrics.

I probably need to sort out that hose before trying to bleed anything because otherwise it'll just happen again, and I need to check if that hose is actually okay and it is just the clamps, or if it's actually a damaged hose end. I've tightened it up a few times and it's still leaking a tiny bit of coolant.

I'm probably out all day tomorrow so maybe Friday morning might be a chance, will keep you posted thanks Arthur [thumbsupbig]

[trout1105]

Although an absolute pain in the bum to fit and remove I think that the LR hose clamps are a better option to the standard screw tightening clamps because they are spring loaded and maintain their pressure to hold the hose better.
As long as new ones are fitted each time a new hose is fitted I haven't had any problems with these types of clamps and they never need to be tightened after the initial fitting like the standard hose clamps do [thumbsupbig]

[Young Angus]

So if I was taking it for a big drive today should I worry too much about needing to give it a bleed or will it be okay so long as I can put up with that noise for ten minutes?

[AK83]

It'd depend on what sort of driving you've done or been doing since the issue started.

One of the reasons I think your coolant bleeding isn't the issue, is that of the few times I've had massive overheating, it's been the result of my less than capable bleeding knowledge.
If you've got air in the coolant I'm sure you'd also have overheating issues too.
Even on short drives just to work, or to the shops or a quick test run to get it to operating temps .. I've mucked up the bleeding program, it's still had air in the system, and instead of settling at about 83°C for the coolant level, it's rocketed to 100°C, and I'm going ... :eek2:
So, I bleed it a bit more on the side of the road, and still the same issue.

Normally! when the coolant system is all good and I get excessive heat due to running the aircon, the dash temp gauge doesn't budge even a millimeter, and my coolant gauge will show mid to high 90's.
A couple of times with this aircon heating up issue, I've seen 103-105ish on the coolant gauge, and only then will the dash temp gauge start to move.

When I mis-bleed the coolant tho, the dash gauge moves much quicker, and well before 100°C shows on the coolant gauge.
Can't remember exactly, but I do remember a couple of times, where (it stuck in my head) I've seen the dash needle rise at 94°C and 98°C shown on the 1Gauge.

If you have the time today, you could try a quick short bleed.
What I do which works perfectly first time every time now:

Get any old drink bottle and cut the bottom of it to turn it into a funnel. If you have a suitable funnel, even better! But you don't need an excessively large volume. I find a 500-600ml bottle to work fine.
Make sure rad is full. If there's coolant in the reservoir, then there should be coolant in the rad. If you open the rad plug(nut), it will overflow out continuously as the reservoir is higher .. ie. gravity.
So the trick is to only just open the plug and close it up ONLY when there is still some coolant in the reservoir. Don't let the reservoir lose coolant and then close the rad plug!

Then use the funnel/cut bottle on the reservoir, fill it to a mid-high mark on the funnel, make sure your vent heater is on(just in case) .. and the open the plug on the top of the thermostat housing to allow coolant to flow out.
The higher level of the funnel at the reservoir forces the coolant out of the thermostat housing and eventually the air pockets too.
If the D1 is parked on a slight uphill angle it apparently helps too, as it keeps the heater hoses a bit lower than the high point of the thermostat housing.(I haven't tried that yet)

Don't let the coolant level in the funnel get lower than about an inch or two from the reservoir end with the bleed cap loose.
The idea is that you want coolant in the funnel whilst you're closing the bleed cap plug. Even just to the point of it being finger tight. So it's an easy on person two handed operation.
You will end up with a bit of overspill as you'd expect around the reservoir, and the reservoir will be overfull .. but that won't be an issue, it will eventually settle to a level that the system prefers on it's own after a few drives.

Really easy to do and should take only a few mins.
*The thermostat housing plug(the bleed nut/cap/plug/whatever) should be pre loosened.
*Engine coolant doesn't need to be hot! I do it from stone cold.

Remember I'm not a mechanic, but every other car I've bled coolant for, has been engine idling, coolant warm, heat and pressure has expelled coolant from the small bleed nipple/nut/port.
300 Tdi had me confused for ages in using the same method on it. Never worked properly or had to do it a zillion(err. Ok, maybe three or so) attempts to get it to be fully air free. Used to frustrate me no end!
The above bleed description is the best, most reliable way(noting that it was first described by blknight that I recall).

[DiscoMick]

Can I ask if taking the cap off the overflow reservoir, but not opening anything else, and then idling the engine, would force air out through the reservoir on a 300Tdi? Just curious.

[trout1105]

So if I was taking it for a big drive today should I worry too much about needing to give it a bleed or will it be okay so long as I can put up with that noise for ten minutes?

These alarms are there to protect your engine, I personally would get this problem "Sorted" Before using the truck.
Overheating a LR engine can have insanely expensive results.

[towe0609]

My alarm, same as yours, was going off when cold sometimes, and sometimes while driving ... intermittent. I had a p-gasket leak and coolant level had dropped 'a bit' in the expansion tank. Topped up the coolant level - fixed. I hope yours is as simple.

[BathurstTom]

Bleeding a 300tdi is easy. Take off cap on reservoir, the bung on top of thermostat housing and the coolant alarm from top of radiator. Fill through thermostat housing until water is at top of radiator (where coolant alarm goes). Replace coolant alarm. Continue filling through thermostat housing until water is at top of thermostat housing. Replace bung at top of housing and replace cap of reservoir. Reservoir will be a little overfull, but the system will get rid of the excess water. It's really that simple and quick.

Tom.

[CraigE]

Are you using any coolant at all? Even small amounts. If not likely needs to be bled properly. I found a good way to get the last air lock out is to top the last little bit with a syringe forcing the last little bit of air out. Mine was doing this for a while using only very minute amounts of coolant, with me thinking a slight leak from the bottom hose. Turned out to be a cracked head. Coolant alarm does not sound at all anymore, but hope that is not your case.

[Young Angus]

I have a visible small leak from the house going to the water pump so I guess it is using a very minute amount of coolant, but there is a tiny hole somewhere so air might be getting sucked back in.

Funnily enough this morning when I took off the alarm didn't go off at all so I thought after having tightened the hose again it didn't let at more air back into the system...But then after I drove it and let it cool down (without incident) the next time I fired it up the alarm did it's thing again, albeit not for as long but still did it the stupid thing.

I'm going to get it pressure tested tomorrow morning and maybe have that hose leak checked out.

[Young Angus]

https://www.aulro.com/afvb/images/imported/2018/01/106.jpg

By the way, anyone have a screwdriver big enough to fit in this thing? I was expecting something to wrap a spanner around, but this is completely round!

[trout1105]

I have a visible small leak from the house going to the water pump so I guess it is using a very minute amount of coolant, but there is a tiny hole somewhere so air might be getting sucked back in.

Funnily enough this morning when I took off the alarm didn't go off at all so I thought after having tightened the hose again it didn't let at more air back into the system...But then after I drove it and let it cool down (without incident) the next time I fired it up the alarm did it's thing again, albeit not for as long but still did it the stupid thing.

I'm going to get it pressure tested tomorrow morning and maybe have that hose leak checked out.

I am pretty sure that your alarm is doing exactly what it is supposed to do and is warning you that your coolant level is low.
The more you drive and ignore the alarm the greater the chance of damaging your engine, Get it fixed ASAP is my advice.
A coolant leak anywhere regardless of the size of the leak is a Problem, Have you tried bleeding the cooling system yet to remove any residual air in it?

[Young Angus]

I am pretty sure that your alarm is doing exactly what it is supposed to do and is warning you that your coolant level is low.
The more you drive and ignore the alarm the greater the chance of damaging your engine, Get it fixed ASAP is my advice.
A coolant leak anywhere regardless of the size of the leak is a Problem, Have you tried bleeding the cooling system yet to remove any residual air in it?

I went to open that thermostat bleed plug but it's a big round plug isn't it, with a huge slot for what I can only imagine is a giant size screwdriver...how the heck do you open those things when they're round? I was expecting it to be a hex!

[trout1105]

I went to open that thermostat bleed plug but it's a big round plug isn't it, with a huge slot for what I can only imagine is a giant size screwdriver...how the heck do you open those things when they're round? I was expecting it to be a hex!

Somebody has done a really good job of mutilating that, You may be able to remove it by using a chisel as a screwdriver But I would be putting a new one on there after you have removed it [thumbsupbig]

[Young Angus]

Somebody has done a really good job of mutilating that, You may be able to remove it by using a chisel as a screwdriver But I would be putting a new one on there after you have removed it [thumbsupbig]

Tell me about it!! They are supposed to be a hex on top though anyway aren't they?? I've never seen a round one in any pics or videos, I mean even if I ignore the damage that has been done to that plug it doesn't look like it was ever easy to get off!

[trout1105]

I am just hoping that this plug isn't indicative of the quality of the work done on your truck by the PO or the mechanics that you have been using.
Why wasn't this addressed when you had the work done on your cooling system recently?, Any fitter that is worth his/her Salt would have replaced that abortion in a heartbeat.

[AK83]

The original bleed plug would have been those horrible plastic types that split break and cause nothing but trouble.
The brass ones aren't original fitment, but back in the day, I remember the early RRC's had that round 'screw driver' slot type plug, and no hex section to use a spanner or socket on.

So I'd say an earlier owner probably had changed it early on and got a brass plug to suit, and that may have been the only option available at the time.

You can get brass plugs with the hex section fairly easily.
Mario(roverlord) has then for sale.
The other use for those brass plugs is for the diff plugs as well.

My personal preference with thos brass plugs tho is not to use a rubber o-ring type seal, but get a copper washer.
If you ever have to muck about with the cooling system, and need to disturb the plugs, the o rings need to be replaced every time(or they leak).
At the moment, with my thermostat plug(which also houses my temp sender) I don't use a sealing washer at all .. doesn't leak.

Get in touch with Mario and get a new plug for it.
Like Trout said, a cold chisel will do the job of removing it.
Once that old type is removed, be very reluctant to refit it .. so prep yourself for that job.

I'd reckon that if a previous owner did all that work to the car over the time they had it, they probably changed the diff plugs to the brass types as well, but to be sure have a peek.

[Pub247]

A pair locking vice grip pliers or a small stillson wrench would probably do it

[BathurstTom]

Or a large screwdriver or some flat steel used sideways. That plug is perfectly round. Looks like it was made that way, not butchered.

Tom.

[trout1105]

The "Shape" of the plug hasn't been butchered but the slot most certainly has.
The amount of use this plug has had leads me to think that there has been an ongoing problem where the system has had to be bled an a regular basis.

[AK83]

.... That plug is perfectly round. Looks like it was made that way, not butchered.

Tom.

Yep definitely the design. Absolute annoyance to remove, especially on the radiator where sideways space was limited.
At least on the thermostat housing you've got lateral space to remove it 'easily'.

Could use a regular screw driver fitted sideways across the entire gap section and 'lever' it off .. but as I said, best that once removed, have the replacement part ready.

I remember eventually getting a tool to remove it, got at a hydraulic/hose type store(like an Enzed). Was a socket like tool with bar at the end to fit into the cavity section.
Like a box spanner used to remove tap valves kind'a thing.

My D1 had the plastic bungs, which I removed almost immediately at the earliest opportunity.
I got a massive stainless 1-1/16 hex nut for the rad, but the brass 3/4 hex nut with the 1/8th NPT access for my sender. Got from a local hydraulics shop.

[edddo]

Mario probably sells replacemnt brass hex plugs.
I think i got mine on ebay
Do people use o rings on these?

[Pub247]

The slot is pretty butchered though

[Young Angus]

I am just hoping that this plug isn't indicative of the quality of the work done on your truck by the PO or the mechanics that you have been using.
Why wasn't this addressed when you had the work done on your cooling system recently?, Any fitter that is worth his/her Salt would have replaced that abortion in a heartbeat.

Well I didn't get a new thermostat housing, just the thermostat and the P Gasket. That plug must just be what I had in there before so I might ask him for a replacement. Not sure why they didn't replace it to be honest, but oh well I'll ask them if they've got something a bit better, and if not I'll just get one from Mario and rip this one off with a set of vice grips!

[AK83]

....
The amount of use this plug has had leads me to think that there has been an ongoing problem where the system has had to be bled an a regular basis.

I wouldn't put it that way.
The plug is brass, and even only one or two removals can easily damage it as it currently is.
It's dependent in the person removing it and what tools they have available to remove it with.

From experience, it wouldn't surprise me if it's only been removed a few times, but as you said, butchered in the process .. but I reckon due to a lack of available tools, more so than the number of times it's been removed and refitted.

What doesn't, and wouldn't, make sense is that if it were butchered due to being removed often because of ongoing issues, that at some point in the extremely difficult removal process, the person would have changed it for the more sensible hex head type!

Under normal circumstances I wouldn't describe myself as sane, but only an insane person would persevere with a plug of that design in an ongoing situation and not consider an alternative plug type.
Back in my RRC days, I remember difficulty in getting these back on, so even for an 'insane' person such as myself enough was enough and a better solution was sought.

Having been told of a brief history of Ben's D1, it seems very unlikely that the effort that the previous owner to maintain the vehicle, that they'd have persevered with that plug if there was an ongoing issue.
Ben's had the D1 for a good number of years now, and hasn't relayed any ongoing issues of that type either.

The reality of the situation is simply down to a few basic points. The plug is brass, which is soft. It's an extremely annoying design, for which hardly any tools exist for it, and the 'operator' will usually resort to some cobbled up tool/s to remove and refit.
In that process, the tool will almost certainly slip the first attempt, so the operator then has to get a feel for what operation style might work .. and they'll probably slip for that modified attempt too.
By this second attempt, it's guaranteed that the soft brass edges of the slot have been butchered, and will only get worse now due to the wear and additional attempts to remove or refit.

[Fausto79]

Tell me about it!! They are supposed to be a hex on top though anyway aren't they?? I've never seen a round one in any pics or videos, I mean even if I ignore the damage that has been done to that plug it doesn't look like it was ever easy to get off!

I use a 2ish mm (whatever the slot size is) piece of steel that i cut. Bout 4cm x 2cm. Could be any size. You put it in slot and use adjustable spanner or similar to open it. My radiator one was round like that. I now have one with slot and hex.

The thermostat one had hex but now has my coolant alarm plastic bung on it with rounded edges coz somebody decided to put sealant all round thread when they fixed a leak in my radiator.

[Fausto79]

Actually now I remember. The steel plate i cut is smaller. Still 2 or 3mm thick but small enough to fit inside one of my sockets. I think bout 3/4 inch socket. You slide plate into it, then clip socket onto breaker bar and put it into slot on bung and turn. Works like a charm.

[trout1105]

OK
Young Angus has told us that truck has been leaking coolant from various parts of the cooling system so there is Most likely less than the optimal amount of coolant in the system now and the (faulty) alarm is Most likely working perfectly.
He also said that he has trouble tightening a hose clamp on the water pump enough to stop it leaking, I suspect a corroded water pump inlet is the culprit here and hopefully this is what is causing the coolant loss.
As the system needs to be bled anyway it wouldn't hurt to remove the hose from the water pump to inspect the integrity of the metal for corroision/holes and to see if this is the problem.

[AK83]

I have a visible small leak from the house going to the water pump so I guess it is using a very minute amount of coolant ....

The clamp on the water pump hose doesn't look ideally fitted. It looks too far to the edge of the hose.
In theory it shouldn't make a difference, but I had a similar thing with my top radiator hose too.

When I removed it to do the timing belt .. and then put it back, I couldn't get it to stop dripping no matter how tight I went. Got a new clamp thinking I'd a REAL good tightening .. nup!
I pulled the clamp back a few mm, further in from the edge of the hose, and closer to the raised edge of the inlet pop, normal tightness to start with .. bingo!

[Fausto79]

careful with tightening clamps. mainly on the radiator but i had one of those heavy duty ones which i put on too tight to my new cored radiator and squeezed the bottom barb. ended up making a little hole which when under pressure would spray a jet of coolant all up into the bonnet area, making it almost impossible to detect. ended up getting professional to look at it.

one thing you may want to consider and although probably unlikely as your alarm goes off, but mine was leaking coolant as well from being over filled. there was too much pressure in there and it was squeezing coolant out where it could. that and also an airlock somewhere. i tried all methods of filling it to try and get air out but i failed at all of them. ended up getting it done when the radiator had to get fixed and been mostly good since. except for the occasional beep when been sitting idle for days or had a long hot run the day before. soon as the engine starts though, the sound goes away as the pressure brings the coolant up to the sensor.

[Young Angus]

Well I'm a little stumped at the moment. Took it back to the mechanic and he said that if there was some kind of air lock it would be carrying on in more ways than just the coolant alarm going off. He couldn't actually open the plug because it was too hot but he's confident it will have plenty of coolant in it and also my heaters and everything work fine. Then another mechanic friend of mine also said that if there was air in there it'd be overheating and not running well. It's not overheating and it's running very well.

Another option is a faulty sensor? Not sure, I'm looking into that.

Nothing has really changed that has done anything to that circuit, even had the guys who installed the lights and UHF look at it for a bit and they said they wouldn't have done anything that touched that.

I guess I can check if it's full at the thermostat first thing in the morning when it's cold, and now I have a replacement hex brass plug (with rubber o-ring) ready to replace it after I get that silly round thing off. But then I won't be able to open the one at the radiator with the sensor on it will I otherwise won't all the coolant pour out of there?

Might just have to get a new sensor, but it just seems to consistent for me to think that something is faulty with the sensor but everyone else seems to think the car is just fine.

[trout1105]

Well I'm a little stumped at the moment. Took it back to the mechanic and he said that if there was some kind of air lock it would be carrying on in more ways than just the coolant alarm going off. He couldn't actually open the plug because it was too hot but he's confident it will have plenty of coolant in it and also my heaters and everything work fine. Then another mechanic friend of mine also said that if there was air in there it'd be overheating and not running well. It's not overheating and it's running very well.

Another option is a faulty sensor? Not sure, I'm looking into that.

Nothing has really changed that has done anything to that circuit, even had the guys who installed the lights and UHF look at it for a bit and they said they wouldn't have done anything that touched that.

I guess I can check if it's full at the thermostat first thing in the morning when it's cold, and now I have a replacement hex brass plug (with rubber o-ring) ready to replace it after I get that silly round thing off. But then I won't be able to open the one at the radiator with the sensor on it will I otherwise won't all the coolant pour out of there?

Might just have to get a new sensor, but it just seems to consistent for me to think that something is faulty with the sensor but everyone else seems to think the car is just fine.

Get New Mechanics [thumbsupbig]
These blokes didn't even physically check the system and just made guesses :thumbsdown:

[Young Angus]

Get New Mechanics [thumbsupbig]
These blokes didn't even physically check the system and just made guesses :thumbsdown:

Well I hear you, but I also know they know these engines very well and have loads of experience with Land Rovers in particular the 300Tdi.

So let's say a 300Tdi had some air locked in the system, what actually happens to the engine when you start driving it around heaps? Does it just run as normal or will it misbehave?

[trout1105]

Well I hear you, but I also know they know these engines very well and have loads of experience with Land Rovers in particular the 300Tdi.

So let's say a 300Tdi had some air locked in the system, what actually happens to the engine when you start driving it around heaps? Does it just run as normal or will it misbehave?

First off have you fixed ALL the leaks yet?
Running about with low coolant levels because there is air in the system is Not a great idea, If it was we would all be doing it [bigwhistle]
Fix ALL your leaks then bleed the system yourself so that you "Know" that it has been done properly, Your 300TDI will Love you for it[thumbsupbig]
Do you really want to cross the Nullarbor with a cooling system that you have doubts about?

[AK83]

Well I'm a little stumped at the moment. Took it back to the mechanic and he said that if there was some kind of air lock it would be carrying on in more ways than just the coolant alarm going off. He couldn't actually open the plug because it was too hot but he's confident it will have plenty of coolant in it and also my heaters and everything work fine. Then another mechanic friend of mine also said that if there was air in there it'd be overheating and not running well. It's not overheating and it's running very well.....

That was my point re needing a bleed. If it needs to be bled again, it'd be overheating and in this case the dash gauge is almost sure to move.
It's the only time I get to see the gauge move.


...
Another option is a faulty sensor? Not sure, I'm looking into that .... Nothing has really changed that has done anything to that circuit, even had the guys who installed the lights and UHF look at it for a bit and they said they wouldn't have done anything that touched that. ...

I'm more inclined to suspect wiring as a priority. Can you trace the wiring, or is a messy install?
Not saying that those guys stuffed anything, just that with the additional 'load' maybe it's playing havoc with the alarm thing.


....
I guess I can check if it's full at the thermostat first thing in the morning when it's cold, and now I have a replacement hex brass plug (with rubber o-ring) ready to replace it after I get that silly round thing off. But then I won't be able to open the one at the radiator with the sensor on it will I otherwise won't all the coolant pour out of there?

Might just have to get a new sensor, but it just seems to consistent for me to think that something is faulty with the sensor but everyone else seems to think the car is just fine.

Definitely do the thermostat housing plug now you have a proper one.
Rip into the other one any way you can. A long-ish screw driver or piece of flat steel or something used like a lever bar across the slot isn't too hard to do. Hopefully when the timing belt mechanic redid it up when they bled it it's freed up enough for you to remove easily(ish).
They seem to 'weld' themselves on over time with non use. I think the heat-cold cycles tighten them up and makes them harder to remove .. why that design is so silly.

Wouldn't worry about the rad plug. When you remove the thermostat plug fill it up with water/coolant from there. Cap it finger tight so that you can undo it easily and then do the old drink bottle cut open and inverted on the coolant reservoir trick. Fill the drink bottle to above the height of the thermostat cap.
Keep adding coolant/water to the drink bottle so that it's always higher than the plug, open the plug to allow excess water to escape. I do it a few times(3, 4, 5 .. whatever), and you get the occasional air pocket come out of the bung.
I think the main issue on level ground is that the heater hoses are just a touch higher than the plug itself, so the extended height of water via the drink bottle method helps to get air out of the heater hoses.
If you can park the D1 slightly uphill, so that the heater hoses can be a bit lower than the thermostat bung it'd probably help a little too.

[Young Angus]

First off have you fixed ALL the leaks yet?
Running about with low coolant levels because there is air in the system is Not a great idea, If it was we would all be doing it [bigwhistle]
Fix ALL your leaks then bleed the system yourself so that you "Know" that it has been done properly, Your 300TDI will Love you for it[thumbsupbig]
Do you really want to cross the Nullarbor with a cooling system that you have doubts about?

Leaks are fixed but have not bled it myself yet so I guess that's next. I've never bled the system so that's some good experience to add to the list for my trips [thumbsupbig]

[Young Angus]

I'm more inclined to suspect wiring as a priority. Can you trace the wiring, or is a messy install?
Not saying that those guys stuffed anything, just that with the additional 'load' maybe it's playing havoc with the alarm thing.

--------------------------------------------

Wouldn't worry about the rad plug. When you remove the thermostat plug fill it up with water/coolant from there. Cap it finger tight so that you can undo it easily and then do the old drink bottle cut open and inverted on the coolant reservoir trick. Fill the drink bottle to above the height of the thermostat cap.
Keep adding coolant/water to the drink bottle so that it's always higher than the plug, open the plug to allow excess water to escape. I do it a few times(3, 4, 5 .. whatever), and you get the occasional air pocket come out of the bung.
I think the main issue on level ground is that the heater hoses are just a touch higher than the plug itself, so the extended height of water via the drink bottle method helps to get air out of the heater hoses.
If you can park the D1 slightly uphill, so that the heater hoses can be a bit lower than the thermostat bung it'd probably help a little too.

Might try checking out the wiring, make sure they're good decent wires.

I actually emailed David from Engine Saver and he suggested taking out the sensor plug in the radiator and cleaning it with an old toothbrush and some Jif, so might give that a go before it warms up, also he said if I leave the header tank cap on there shouldn't be too much spillage...we'll see about that haha

Someone actually wrote somewhere online that they unbolted the whole header tank and just had someone hold it up higher than the rest of the engine for the bleed process so there was no mucking around with a coke bottle, I haven't actually looked yet to see how it's bolted on but kind of sounds like a nifty idea if it's actually possible.

[trout1105]

Leaks are fixed but have not bled it myself yet so I guess that's next. I've never bled the system so that's some good experience to add to the list for my trips [thumbsupbig]

Perfect [thumbsupbig]

[BathurstTom]

Get a new mechanic. He's just lazy. To say that it doesn't have air in it without even checking is nothing short of pathetic. With the low coolant doing what low coolant alarms do, it makes it doubly so. You know yourself that it has been leaking. Don't let it cost you a motor.

Tom.

[Don 130]

Dave Blknight's method is the answer

the coke bottle method works well..

fill the cooling system at the tank with the radiator plug out.
when it flows out there install the plug and add more coolant
invert a coke bottle (2l) full of coolant into the neck of the header tank then start it up and maintain high idle untill the coolant in the coke bottle begins to heat up or the coke bottle purges down into the cooling system (squeezing it can help)

if the bottle empties repeat the process.
Dave .

"In a Landrover the other vehicle is your crumple zone."

For spelling call Rogets, for mechanicing call me.

Fozzy, 2.25D SIII Ex DCA Ute
TDI D1(its responded well to its lecture about poor performance)

If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
If you think you're in front on the deal, pay it forwards

[biggin]

So you still haven't cleaned the sensor?
Takes all of five minutes.

[Young Angus]

https://www.aulro.com/afvb/images/imported/2018/01/147.jpg

So first off, just removed radiator plug with sensor to give it a good clean and coolant did not pour out, nor was it right up the top but very close to it, I'll take a photo of that next. Is this meant to pour out if I open this?

Also a little rust on the sensor so gonna clean it off now.

Should I top this up at this point before opening the thermostat plug and topping up there too?

[Young Angus]

https://www.aulro.com/afvb/images/imported/2018/01/146.jpg

Better!

[jboot51]

In theory it should overflow slightly when removing the bung. But the height difference to the thermostat housing is next to nothing so it could take a while.
Have you cleaned out the 3 way ejector between the rad, expansion tank and thermostat housing.
The ejector removes the air and puts it into the expansion tank.
It should be clear in all 3 directions.
With the thermostat closed there should be coolant flow from the thermostat housing to the expansion tank, this flow causes a venturi effect in the ejector and draws fluid/air from the top of the radiator.

[jboot51]

To fill the radiator I remove both bungs and fill from the expansion tank.
The coolant should fill the rad first, install bung.
keep adding coolant to the expansion tank untill coolant can be seen at the thermostat housing, massaging the bottom hoses will move the coolant quicker.
You wont get coolant out the top of the thermostat housing, it defies the laws of physics.
Install the bung and remove the 1/4 hose from the thermostat housing, this is my bleed point. Start the engine, Coolant will come out of the 1/4 barb, refit the hose and it should be good.

[AK83]

....
You wont get coolant out the top of the thermostat housing, it defies the laws of physics.
.....

Not if you don't over fill it, it won't.
But if you continue to fill the reservoir beyond overflowing, the thermostat housing will also overflow(at a lesser rate).
As implied tho, the thermostat housing bung is higher than the coolant reservoir cap. So if you fill the reservoir only to the top of the cap threads, the thermostat housing WON'T be full.

This is why the drink bottle trick works well and gets all air out first time every time. You raise the coolant level to well above the thermostat housing level and cap the thermostat bung by hand and you're done.

If it came to a contest between unbolting the coolant reservoir or using an old bottle inverted into the reservoir, in terms of practicality and ease the drink bottle wins every time!

[Young Angus]

Can I ask, if I open up the thermostat and there is plenty of coolant in there so I even need to bleed the system? Ot just top up the radiator under the sensor?

[AK83]

So first off, just removed radiator plug with sensor to give it a good clean and coolant did not pour out, nor was it right up the top but very close to it, I'll take a photo of that next. Is this meant to pour out if I open this?

Also a little rust on the sensor so gonna clean it off now.

Should I top this up at this point before opening the thermostat plug and topping up there too?

Did you have the reservoir cap on?
If so, maybe the lack of additional air pressure on the higher water level in the reservoir(ie. a partial vacuum) could have stopped the flow out the radiator?
Dunno! every time I open the rad plug, I also have the reservoir cap off too.. and it flows out.
Other possible reasons is the level in the reservoir. While it's not a lot higher, it's still higher than the top of the rad, and a full reservoir should drain out with the rad cap off.

'good' to see some rust on that sensor doodad .. to be sure! not good that it's rusted! .. good in the sense that hopefully it's the source of your annoying issue.

What I do for the rad: reservoir cap off, rad bung(or in your case, the sensor) half on/off so that it leaks.
Fill reservoir continuously so that you get a flow out of the half fitted rad cap.
In a sense, your trying to expel any air in the rad too. Hopefully the rad sensor cap thing is an easy hand tightening job too and as you pour water/coolant into the reservoir slowly tighten the rad cap too.

With that rust on the sensor, there is a possibility that you may have rusty scale build up in your coolant system too. If so, it could clog up the rad.

**additional useless info **
A few weeks ago my CEM products came in the mail and the first thing I did was to test the coolant flush stuff. Left it in for a day or so to circulate around then did a flush with the garden hose.
Old coolant came out much more brown that I used to see it in the reservoir which was basically clean water(I've been using straight water for the past year or so).
So this CEM stuff has definitely cleaned something out of the cooling system. When I flushed the rad too, in both directions with the hose, brown coloured water came out from the bottom hose port, but clear water coming out of the top!
Obviously some build up in the bottom of the rad. I reckon I had to back flush the rad at least 10-15 mins alternating between forward and back flushing to clear the flow out the bottom.
Engine basically flowed clean, with some residual green coolant in there.

Actually ended up with a bit of an improvement in coolant temps, which was what I'm chasing .. only with thee A/C on.
Without A/C on, coolant temps stick to high 70's - low 80's without fail, no matter the engine load.

With A/C, in mid 30's ambient, coolant would easily pass 100°C on an easy cruise. Add even a slight rise in the road, and 105° would come quickly and then the dash gauge would climb towards the red, never actually go into the red .. just an indication that it's warming up.
I'd have to both back off almost totally, and turn A/C off and it'd settle back down to about mid to high 90's for a long while after that.. it was hard to moderate the use of the A/C as it's get hot so quickly with it on .. etc.

Other week I went for a bit of a drive .. lots of 40°C ambients between Cobar/Wilcannia/Broken Hill/and Menindee.
I got many instances of 700°C EGT temps which had me backing right off and dropping into 3rd(auto) to keep them in check, but coolant temp never passed 100°C and only hit that 100°C temp for a split sec. Mainly sat at about 95-97°C according to the data log.

I suspect that the bottom of the rad was partially blocked!

Did the chap in Monbulk give the coolant a refresh/flush/etc? was that part of the service?
Did he refill with coolant? ie. do you have coolant in the system.
I'd suggest(with the rust on that sensor) to give the coolant a flush while you're there doing all this other stuff.

ps. you can run straight water too .. don't really need coolant, they say it supposed to help with boiling point level, but the trick is to not allow it to get to boiling point! ;)
Like I said, I've been running straight water for over a year now.
Will eventually top with coolant(got a large 20lt drum of it now) .. just been lazy and more accurately I'm still in between flushing phases AND trying to get off the posterior to do my silicon hoses change.

[Young Angus]

https://www.aulro.com/afvb/images/imported/2018/01/148.jpg

There's plenty of coolant in the rad and it touches the sensor pin when I put it in. Maybe it's a corrosion thing after all.

I am trying to avoid having to bleed it myself if I don't have to right now because I'd rather not double handle if I don't have to, but if it keeps happening after I try this out now having cleaned it then that'll be the next port of call.

[Young Angus]

Did you have the reservoir cap on?
If so, maybe the lack of additional air pressure on the higher water level in the reservoir(ie. a partial vacuum) could have stopped the flow out the radiator?
Dunno! every time I open the rad plug, I also have the reservoir cap off too.. and it flows out.
Other possible reasons is the level in the reservoir. While it's not a lot higher, it's still higher than the top of the rad, and a full reservoir should drain out with the rad cap off.

'good' to see some rust on that sensor doodad .. to be sure! not good that it's rusted! .. good in the sense that hopefully it's the source of your annoying issue.

What I do for the rad: reservoir cap off, rad bung(or in your case, the sensor) half on/off so that it leaks.
Fill reservoir continuously so that you get a flow out of the half fitted rad cap.
In a sense, your trying to expel any air in the rad too. Hopefully the rad sensor cap thing is an easy hand tightening job too and as you pour water/coolant into the reservoir slowly tighten the rad cap too.

With that rust on the sensor, there is a possibility that you may have rusty scale build up in your coolant system too. If so, it could clog up the rad.

**additional useless info **
A few weeks ago my CEM products came in the mail and the first thing I did was to test the coolant flush stuff. Left it in for a day or so to circulate around then did a flush with the garden hose.
Old coolant came out much more brown that I used to see it in the reservoir which was basically clean water(I've been using straight water for the past year or so).
So this CEM stuff has definitely cleaned something out of the cooling system. When I flushed the rad too, in both directions with the hose, brown coloured water came out from the bottom hose port, but clear water coming out of the top!
Obviously some build up in the bottom of the rad. I reckon I had to back flush the rad at least 10-15 mins alternating between forward and back flushing to clear the flow out the bottom.
Engine basically flowed clean, with some residual green coolant in there.

Actually ended up with a bit of an improvement in coolant temps, which was what I'm chasing .. only with thee A/C on.
Without A/C on, coolant temps stick to high 70's - low 80's without fail, no matter the engine load.

With A/C, in mid 30's ambient, coolant would easily pass 100°C on an easy cruise. Add even a slight rise in the road, and 105° would come quickly and then the dash gauge would climb towards the red, never actually go into the red .. just an indication that it's warming up.
I'd have to both back off almost totally, and turn A/C off and it'd settle back down to about mid to high 90's for a long while after that.. it was hard to moderate the use of the A/C as it's get hot so quickly with it on .. etc.

Other week I went for a bit of a drive .. lots of 40°C ambients between Cobar/Wilcannia/Broken Hill/and Menindee.
I got many instances of 700°C EGT temps which had me backing right off and dropping into 3rd(auto) to keep them in check, but coolant temp never passed 100°C and only hit that 100°C temp for a split sec. Mainly sat at about 95-97°C according to the data log.

I suspect that the bottom of the rad was partially blocked!

Did the chap in Monbulk give the coolant a refresh/flush/etc? was that part of the service?
Did he refill with coolant? ie. do you have coolant in the system.
I'd suggest(with the rust on that sensor) to give the coolant a flush while you're there doing all this other stuff.

ps. you can run straight water too .. don't really need coolant, they say it supposed to help with boiling point level, but the trick is to not allow it to get to boiling point! ;)
Like I said, I've been running straight water for over a year now.
Will eventually top with coolant(got a large 20lt drum of it now) .. just been lazy and more accurately I'm still in between flushing phases AND trying to get off the posterior to do my silicon hoses change.

Yep the other caps were all still on so I guess there is no other hole to allow anything out of the system, even though it may be lower in height.

The radiator got totally taken out and flushed and checked and had it's own personal pampering service done on it. Apparently it was 40% blocked but still in great nick so they gave it a good proper clean out and put it back on and put all new coolant (with all new hoses as well) and bled the system etc. etc. So I've got no doubts the radiator is clean and lovely.

[Vern]

Mine did this all the time as i said before, i put a 10mm longer bolt in the sensor to stop the alarm intermittently going off until warm.

[Young Angus]

Slight problem...Can't get the thermostat plug out at all and I think I damaged it a little bit more [emoji52]

[trout1105]

Yep the other caps were all still on so I guess there is no other hole to allow anything out of the system, even though it may be lower in height.

The radiator got totally taken out and flushed and checked and had it's own personal pampering service done on it. Apparently it was 40% blocked but still in great nick so they gave it a good proper clean out and put it back on and put all new coolant (with all new hoses as well) and bled the system etc. etc. So I've got no doubts the radiator is clean and lovely.

When I first got my D2a it was running a bit hot so I had my radiator "Rodded" by Natrad for about $500, They then filled up the system with a Glycol based coolant which had to be replaced because this type of coolant is unsuitable for the 4l V8 and was told that it can cause head gasket failures.
The head gaskets DID fail a couple of years later, I am not convinced that the incorrect coolant was the cause of this but it only takes that one extra straw to break a camels back[bigwhistle]
I recently had a brand new radiator fitted for about $300 as part of the engine rebuild because the old radiator was now RS So Not only did I waste $500 at Natrad I had to add another $50 worth of coolant at the time as well.
Tarting up an old radiator may be a good idea on an old "Banger" that you are just using to mess about with around town or out the back paddock But I personally am not now convinced that it is a good idea for something that you want to take on an extended trip or to remote areas.
It can also work out less expensive to replace the radiator with a new one than getting the old one fixed up as well [thumbsupbig]

[biggin]

Yeh, the sensor looks a little shorter than the V8 version in the top hose that I have.

[kreecha]

Wow. I've been following this thread for awhile now and it is quite long!

Anyway after all these posts, and at the chance of being non WH&S savvy, for my D1 which also did this, I replaced the sensor screw with one 10mm longer from local chandlery store and to bleed the system I just ran the engine with the screw out and filled the reservoir. Eventually coolant came out of the sensor thread and I put the screw in.

Just my $0.02 [emoji106]

[kreecha]

Slight problem...Can't get the thermostat plug out at all and I think I damaged it a little bit more [emoji52]

Plastic or brass?

[trout1105]

Slight problem...Can't get the thermostat plug out at all and I think I damaged it a little bit more [emoji52]

Give the top of the plug a few light taps with a hammer to loosen it up a bit, Then undo it.
What are you using to undo that mangled plug?

[Young Angus]

GOT IT!!

[Young Angus]

All pretty full too https://www.aulro.com/afvb/images/imported/2018/01/149.jpghttps://www.aulro.com/afvb/images/imported/2018/01/150.jpg

[Young Angus]

A sweet pair of vice grips and my Dads golden touch (I loosened it for him definitely) and it came loose. Topped up the thermostat housing with water even though it was already full and then put some vasalene on the rubber o ring and put the new plug in and took it for a drive...

.....

Noise...GONE! I think it was just a crummy dirty sensor. Had air con going on this lovely 41 degree day and ran like a charm, no bleeding required.

I did ask them to comment on weather the radiator was worth replacing with a new one or not so they had their chance to sell me something new but they said it was still in great shape. Not sure if it's original or not, think it was replaced somewhere along the line by PO but will have to check records.

Is there a good better option for replacement radiators for these? I seem to remember reading something that said replacement radiators for these were made of something that was less reliable than original units??? No idea where I read that though or if it's even correct...

[AK83]

.....

Is there a good better option for replacement radiators for these? I seem to remember reading something that said replacement radiators for these were made of something that was less reliable than original units??? No idea where I read that though or if it's even correct...

You can check your rad to see if the components are plastic side tanks and copper fins or a full copper(ie., copper side tanks too).
Actually scratch that! .. had another look at your pics and that rad plug side definitely looks copper .. so you got about as good as it gets.

Like I said earlier tho, don't be fooled by the clear looking colour of the coolant.
I'd quadruple checked mine over the course of many months hot and cold, and my water(only) looked clean enough to drink .. (only in an emergency of course! :p) .. but having used that coolant flush recently and seeing brown water coming from the bottom of the rad made me think again.

I still have an ebay aluminium rad to try out on mine one day too. Had it for well over a year sitting, waiting for the day to try it's luck at keeping mine cool with the A/C on.
But I wanted to do it with a new frame and larger intercooler.
I reckon I'll do it all the week after next with all the new silicon hoses and stuff.

Actually! .. today would have been a nice day to get out there and get wet with all that type of work .. to hot(currently 41 here too).

[Young Angus]

Haha yeah this 41 degrees can just get lost...good for testing out cooling systems though ;)

So are there any benefits to the aluminium rads over the copper ones or is that just what they make these days?

[AK83]

I suppose in the next couple of weeks I'll find out if the aluminium rad is any better or worse than my copper one.
Al is cheaper and lighter.
So I suppose one benefit of Al radiators is that you can upsize it without making it heavier than a copper rad.

I don't think any car makers use copper rads in their new models nowadays .. haven't seen a new car with a copper rad for years!

[Young Angus]

I suppose in the next couple of weeks I'll find out if the aluminium rad is any better or worse than my copper one.
Al is cheaper and lighter.
So I suppose one benefit of Al radiators is that you can upsize it without making it heavier than a copper rad.

I don't think any car makers use copper rads in their new models nowadays .. haven't seen a new car with a copper rad for years!

This looks like a good read, sounds like it's more or less a very similar outcome no matter which way you go, but you probably won't get modified different design radiators made out of anything but aluminium I'd say.

Aluminum VS. Copper-Brass Radiator: Final Thoughts (http://www.cgj.com/2013/07/16/aluminum-vs-copper-brass-radiator-final-thoughts/)

[donh54]

Seeing quite a few references to water in this thread. Hopefully they're using it to bring a concentrate to the right ratio.
Flushing aside, even for a short time, water on its own is a no-no for iron block/alloy head engines.
I was told once by a motor engineer that once that corrosion starts, it cannot be stopped, and the residue starts coating the water galleries and the inside of the radiator tubes. Adds up to more cooling problems down the track.

[AK83]

.... but you probably won't get modified different design radiators made out of anything but aluminium I'd say....

There is one shop in Bendigo ... Bendigo Radiators (https://www.bendigoradiators.com/services2-c10qp) .... that does a modded copper rad(or two).
Very expensive mods tho .. think around the $700 mark.

[edddo]

What material are the radiators in Landcruisers, 79 utes, Rangers etc made from...ie other brands that get out into the bush/corrugations etc?
Seems common to hear that the aluminium radiators do NOT stand up well to the rigours of real 4WDing/outback touring.
Based on that I am looking to replace my rad with a good copper one when the time comes.

edit: oops omitted a very importnat 'NOT'

[AK83]

What material are the radiators in Landcruisers, 79 utes, Rangers etc made from...ie other brands that get out into the bush/corrugations etc?
.....

They'll be the normal aluminium/plastic bonded and crimped types.

The way I see it, if truck makers are happy to use that type nowadays, there's not really much of an issue in terms of durability.

[izu]

Check coolant level before starting engine when cold. Coolant level will rise when engine warms up.

[Kerry]

Mine does that the day after a long drive or if it has been sitting idle for a few days. Usually only keeps beeping until the engine is turned on. Once it was beeping on and off like you say and i unscrewed the bolt and dripped some coolant in. Then ran car and bled air out.

Mine is on top of thermostat housing though.

The sensor should not be at the thermostat housing because the pump keeps sending coolant onto it long after you have dumped a lot of coolant. I had mine there and found out the hard way. It must be at the radiator filler plug. If it is an Engine Saver, you can find out more on their web site.

[AK83]

The sensor should not be at the thermostat housing because the pump keeps sending coolant onto it long after you have dumped a lot of coolant. I had mine there and found out the hard way. It must be at the radiator filler plug. If it is an Engine Saver, you can find out more on their web site.

Me thinks you had another issue of some kind.

Are you suggesting that the waterpump flows coolant directly into the thermostat housing?

Water pump coolant flows into the block, not the thermostat housing.
So while you're correct, it's the same as almost every other system .. once you have low coolant levels, you start getting overheating.

Technically it shouldn't really matter if it's fitted in the thermostat housing or radiator cap.
If you have sufficient levels of coolant to maintain an acceptable temp in the engine, then low coolant or not, it makes no difference.
If the coolant level is too low to maintain an acceptable engine temp(ie. not overheating) then a coolant temp gauge will display the same problem.

Low coolant alarms are all well and good, but I'd prioritise an actual working coolant gauge first, and keep an eye on coolant temps.

[edddo]

Hey Yangus
You havent voted in the ‘what landy do you currently own’ poll
It is in the general chat section

[Young Angus]

Hey Yangus
You havent voted in the ‘what landy do you currently own’ poll
It is in the general chat section

Oops I'll get over there right now...sorry I haven't had much time for the forum this last week, been back at work and run off my feet...I just want to go driving I don't want to have to work so darn hard!

[Kerry]

Me thinks you had another issue of some kind.

Are you suggesting that the waterpump flows coolant directly into the thermostat housing?

Water pump coolant flows into the block, not the thermostat housing.
So while you're correct, it's the same as almost every other system .. once you have low coolant levels, you start getting overheating.

Technically it shouldn't really matter if it's fitted in the thermostat housing or radiator cap.
If you have sufficient levels of coolant to maintain an acceptable temp in the engine, then low coolant or not, it makes no difference.
If the coolant level is too low to maintain an acceptable engine temp(ie. not overheating) then a coolant temp gauge will display the same problem.

Low coolant alarms are all well and good, but I'd prioritise an actual working coolant gauge first, and keep an eye on coolant temps.

I sure did have 'another issue'! My P gasket started leaking S of Alice Springs on my way back to Darwin towing 2.9 tonne van. In A/S i bought some Rislone radiator stop-leak and as soon as i hit the first hill just N of A/S i boiled - and did so every time i hit a hill or got to cruising speed. My heater element blew (bypassed that) and exhaust gas was bubbling into the coolant header tank. I learnt that if i kept the exhaust gas temp below 380C it would not boil - so it was a sloooow trip to Darwin, especially up the hills (sorry road trains!). I put a new Turner performance head from England on (it got to D before me) and had the 3yo radiator cleaned - it was 70% clogged. I will never use a radiator treatment again! Despite boiling several times and losing quite a lot of coolant, the Engine Saver alarm never made a noise. Later i spoke to David at E/S and he alerted me to the fact i had the sender at the wrong place and it was he who told me about the water pump keeping the sender asleep when it is at the thermostat housing. Interestingly, after 440,000km each bore was in perfect condition with honing marks still clearly evident. All is good again.

[AK83]

.... Later i spoke to David at E/S and he alerted me to the fact i had the sender at the wrong place and it was he who told me about the water pump keeping the sender asleep when it is at the thermostat housing. .....

That part doesn't make sense.
Of the info I can find on the coolant flow in a Tdi, the only way the water pump can supply the thermostat housing with water is via the block and head.
The small hose from thermostat housing(passengers side) to the water pump is the bypass that is open when engine is cold, and blocked when engine is at thermostat operating temp.

So coolant flows from pump through engine(and heater core) and back to thermostat housing, and when cold, directly back to water pump.

300 tdi hold about 11 lt of coolant.

it's be in interesting test(from cold) to see if the the bottom rad hose was removed just a little at a time, say to remove 1lt increments, what would be the result of the low coolant alarm's indicator if it were fitted in the thermostat housing or radiator plug.
That is how many lt removed in each location would set it off as the warning.

Not so much for me... I'm not a big fan of low coolant alarms myself... just curiosity on my part. Practicality would imply that the sensor set up at the highest point of the system(which is actually the top heater hose at the back of the valve cover! :p) would make the most sense .. low level sense at the earliest point in time.

Of course I may have my understanding of the flow of coolant in the 300 Tdi completely wrong too tho.

on a separate but similar front: I had a leaky P gasket a few weeks back .. worried me half to death as I'd only just replaced the water pump.
Checked the three long bolts on the waterpump and they must have come loose. Torqued up when I installed the pump, but early one morning with motor still cold, I gave them a double check and they were almost totally loose(not quite, but a nip up with a open ender showed them tighten up as if only half done up! :confused:
When I do torques, I always double check the bolts .. anyhow, re did them, + about 5-10 Nm over(can't remember the value off hand now) .. but I was then off on my little drive .. and no problems with the P gakset.
That was on the 27th Dec.
Having a look into the P-gasket issue .. what an abomination of a design choice!! .. I got a spare gasket now myself .... just in case ;)

[Young Angus]

So I went away with the Disco last weekend, spent all weekend up in the High Country on tracks , lots of low range and probably worked it petty hard with no issues. Hot days too.

Got home and the day after I got back this low coolant alarm started going off again on start up same as before.

I took out the bung in the top of the radiator and it looked dark and kind of corroded again so I got out the trusty toothbrush and gave it a clean with some jif and put it back in and voila...no more alarm!

This was not long after I cleaned it last time though and I can't help wondering if there is something in there that's corroding stuff. This only started happening after I had it serviced and coolant changed etc. Come to think of it, it started happening a few weeks or so after the service...kind of a similar time frame to when this one started happening after I cleaned the sensor last time.

The coolant they put in is green and this is the guys at Uptech and they definitely know what they're doing, at least Tony the boss man does, he loves old Discos and particularly the 300Tdi. So I have no doubts they did it properly but this is just weird.

Is green coolant just green coolant...or are there different types? One that could be the wrong one for this motor and start corroding stuff?

[AK83]

Did they specify on the invoice what coolant they used, or did they just list it as 'coolant'?

[trout1105]

It could be electrolysis that is affecting the sensor.

[Young Angus]

It could be electrolysis that is affecting the sensor.

How do I stop (or check for) this electrolysis?

[Young Angus]

Did they specify on the invoice what coolant they used, or did they just list it as 'coolant'?

Just says "coolant"...thanks guys!

[trout1105]

How do I stop (or check for) this electrolysis?

There is nothing you can do about it But if it is the cause of the problem it will happen regardless of what brand/type of coolant you are using [thumbsupbig]
I have had a Redarc low coolant alarm fitted in my D2a now for about 6 months and I haven't had this problem with mine, The sensors are fitted in the expansion tank.

[Young Angus]

There is nothing you can do about it But if it is the cause of the problem it will happen regardless of what brand/type of coolant you are using [thumbsupbig]
I have had a Redarc low coolant alarm fitted in my D2a now for about 6 months and I haven't had this problem with mine, The sensors are fitted in the expansion tank.Cheers, I'll see if it keeps happening. It's easy to clean every now and then and I know there is coolant in it so I guess it's still doing its job...I just have to keep cleaning the sensor. It'll be like brushing the Discos teeth!

[DiscoMick]

The colour doesn't mean much as coolant can come in both green and red. There are also diesel-specific coolants. Some have anti-freeze. Maybe ring your workshop, tell them about the alarm and ask which coolant they used.
Cooling Systems - Nulon Products Australia (https://www.nulon.com.au/products/cooling-systems)

[Young Angus]

The colour doesn't mean much as coolant can come in both green and red. There are also diesel-specific coolants. Some have anti-freeze. Maybe ring your workshop, tell them about the alarm and ask which coolant they used.
Cooling Systems - Nulon Products Australia (https://www.nulon.com.au/products/cooling-systems)Good idea actually thanks for that, will call them tomorrow.

[Don 130]

I reckon you're releasing an air bubble when you remove that cap, and it may be nothing to do with the colour or contamination of the screw. To test this, back the screw out of the plastic bung, just enough to allow the air to escape. As soon as you see fluid, screw it in quick. Next day, do it again and see if you've got another bubble under that screw. If you have, either you've got air being drawn in to the system as it cools at the end of each days running, or there's gas coming from a leaking head gasket.
Don.

[Young Angus]

So coolant brand was either Bursons concentrate or some Fenix brand. Both green. That's all they could tell me.

[Young Angus]

I reckon you're releasing an air bubble when you remove that cap, and it may be nothing to do with the colour or contamination of the screw. To test this, back the screw out of the plastic bung, just enough to allow the air to escape. As soon as you see fluid, screw it in quick. Next day, do it again and see if you've got another bubble under that screw. If you have, either you've got air being drawn in to the system as it cools at the end of each days running, or there's gas coming from a leaking head gasket.
Don.

I don't usually open it up but I really did have zero problems before the coolant was changed recently.

When I take the bung off the screw is always wet and it long enough to be submerged in the coolant at the top of the radiator which is always high and doesn't drop even when I open the bung.

I was emailing David Jones from Engine Saver today and he was certain I have a problem with the coolant being incorrect and that it needs a flush. It doesn't sound like it should be reacting and corroding like that so I'd rather not risk it and make sure I've got the right stuff in there.

Next question, that has probably been asked a thousand times, what kind of coolant is best??

[Young Angus]

Penrite website recommends Penrite "blue" coolant...

[donh54]

I use Nulon green in the D1
.https://www.aulro.com/afvb/images/imported/2018/03/339.jpg

[DiscoMick]

I wonder if the service and refill has released corrosion and gunk from inside and it is floating around inside and causing problems.
You might need to empty the radiator again, with the bottom hose off, put a slow flowing hose in the top and let the water circulate for maybe half an hour and hopefully flush the gunk out the bottom. Then refit hose and refill with suitable coolant. Doing this can only help.
How old is the radiator? Is it working OK or nearing replacement?

[Young Angus]

I wonder if the service and refill has released corrosion and gunk from inside and it is floating around inside and causing problems.
You might need to empty the radiator again, with the bottom hose off, put a slow flowing hose in the top and let the water circulate for maybe half an hour and hopefully flush the gunk out the bottom. Then refit hose and refill with suitable coolant. Doing this can only help.
How old is the radiator? Is it working OK or nearing replacement?They had the radiator out with the work getting done (timing belt among other things) and I said to check it and replace if necessary, but they checked it and said it was about 40% blocked but all good, so they cleaned it out and put it back in.

[Young Angus]

I can see a bit of a mark under the bottom hose that looks like some coolant may have been leaking from there, but I check the coolant often and it never drops. Also one of the top hoses had a tiny bit dripping out onto the alternator (a really tiny bit) so I'm keen to take the hoses off anyway and check them. Sounds like a good reason to flush it to me!

[Young Angus]

I use Nulon green in the D1
.https://www.aulro.com/afvb/images/imported/2018/03/339.jpgThis premix? Isn't it better to use concentrate or doesn't it really matter?

[donh54]

I can see a bit of a mark under the bottom hose that looks like some coolant may have been leaking from there, but I check the coolant often and it never drops. Also one of the top hoses had a tiny bit dripping out onto the alternator (a really tiny bit) so I'm keen to take the hoses off anyway and check them. Sounds like a good reason to flush it to me!

Often a slight leak only appears under pressure - i.e. when driving. The temp and airflow can dry it up very quickly, and all you see is a slight stain. Wherever there's a stain, treat it as a leak, and attend to it asap.

[donh54]

This premix? Isn't it better to use concentrate or doesn't it really matter?

With the concentrate, you add demineralised water to it to make a 50/50 mix. Premix this is already done for you. That pic was of the small (4 litre) bottle I keep in the car for topups, and other peoples' emergencies! [thumbsupbig]

[Young Angus]

With the concentrate, you add demineralised water to it to make a 50/50 mix. Premix this is already done for you. That pic was of the small (4 litre) bottle I keep in the car for topups, and other peoples' emergencies! [thumbsupbig]Ahh okay well in that case the premix sounds like a good idea...I thought I read somewhere people prefer concentrate but if it's already mixed I can't think why