300TDI coolant loss

[mattims]

My 300TDI defender has lost coolant ever since I have had it, I have fixed a few things and decreased the amount but cannot trace down the final leak/s.

I have replaced all the hoses and water pump and p gasket (that seemed like it was the biggest leak).

I cannot see any evidence of leaking anymore, but it still occasionally loses some coolant. Might go for 2 weeks without losing any. Sometimes it seems like loses half a liter in one drive, seems to be more likely to lose coolant on longer drivers.

Any ideas?

Yesterday I cleaned out the air intake rubber hose, it had some oily sludge from the joint where the cyclone separator thing connects to the turbo but otherwise wasn't bad. It did appear the have some green coloring in here, but I cannot figure out how coolant could be getting in here, at least not without mixing with the oil in the engine. It doesn't use much oil at all and last time I had the rocker cover of the check the valve adjustment there was no trace of oil/coolant sludge in the top of the head.

[AK83]

Do you have a more accurate temp gauge installed than the standard one?
This is probably the most vital piece of extra kit next to an EGT gauge.

That is, do you know for sure that the engine isn't running at 100°C or more. The std gauge won't tell you this.

eg. viscous fan hub may not be working, engine heating up, excess pressure build up coolant needs to go somewhere.

Also are you sure you've done a good system bleed.
Blknight had a great writeup on how to do it properly and easily.
I've bled other cars in my non professional role as 'family car repairer' but the 300 tdi is another world.
I had trouble with mine for a short while losing coolant late last year, and it turned out that I was bleeding the system 'incorrectly'.
blknights method with the inverted bottle fixed me up good and proper too!

[mattims]

I do have an EGT gauge, but still running the standard engine temp gauge. Is swapping to a VDO gauge and sender the usual practice.. my other gauges are VDO just because they look similar to standard ones.

Out of curiosity where is the "vent" in the cooling system if you do get too hot.

I have never had what I believe is high EGT's (only time I have seen over 500 degrees is towing a car trailer up hills, and I shifted down gears and slowed down when it got over 550). But I guess it could have still overheated the engine a bit without that gauge moving much.

I am reasonably confident on the bleeding.. my heater works which I think is the most likely place to have air trapped, but I will double check that guide.



Do you have a more accurate temp gauge installed than the standard one?
This is probably the most vital piece of extra kit next to an EGT gauge.

That is, do you know for sure that the engine isn't running at 100°C or more. The std gauge won't tell you this.

eg. viscous fan hub may not be working, engine heating up, excess pressure build up coolant needs to go somewhere.

Also are you sure you've done a good system bleed.
Blknight had a great writeup on how to do it properly and easily.
I've bled other cars in my non professional role as 'family car repairer' but the 300 tdi is another world.
I had trouble with mine for a short while losing coolant late last year, and it turned out that I was bleeding the system 'incorrectly'.
blknights method with the inverted bottle fixed me up good and proper too!

[Tins]

t.

I have never had what I believe is high EGT's (only time I have seen over 500 degrees is towing a car trailer up hills, and I shifted down gears and slowed down when it got over 550). But I guess it could have still overheated the engine a bit without that gauge moving much.



I wouldn't be too worried about 550˚. That's nothing. 720˚ would be the absolute maximum, and you would not want it to sustain anything like that, but I regularly see 650˚ on mine when it's climbing long hills loaded.

[Tins]

Do you have a more accurate temp gauge installed than the standard one?
This is probably the most vital piece of extra kit next to an EGT gauge.

That is, do you know for sure that the engine isn't running at 100°C or more. The std gauge won't tell you this.

eg. viscous fan hub may not be working, engine heating up, excess pressure build up coolant needs to go somewhere.

Also are you sure you've done a good system bleed.
Blknight had a great writeup on how to do it properly and easily.
I've bled other cars in my non professional role as 'family car repairer' but the 300 tdi is another world.
I had trouble with mine for a short while losing coolant late last year, and it turned out that I was bleeding the system 'incorrectly'.
blknights method with the inverted bottle fixed me up good and proper too!

Failure to bleed properly cost me a head gasket. I thought I knew how, but I didn't. Dave's method is great. The hardest bit is finding a bottle that stands up in the neck of the coolant bottle!

[loanrangie]

when was the radiator last cleaned/rodded out and has the viscous unit been replaced, also check the plastic ejector Y piece hasnt split.

[AK83]

As long as the temp probe is somewhere like the EGR plate, 550°C sounds nice and cold!
if the probe is located downstream of the turbo, 550°C could be at the high end.

Bleeder plug is the large(usually plastic, sometimes fitted with brass) nut on top of the thermostat housing.

After reading blknight's tute, the issue is that the bleeder nut is higher than the actual remote reservoir tank level.
So the problem is that you can't bleed it well enough if you don't extend the level of the reservoir tank level.

Like John said, use a bottle upside down in the filler neck and fill it all the way up.

Venting as I'm now understanding it is the small 3 way plastic sputnik looking doodad at the empty space between reservoir, radiator and thermostat housing.
I broke mine recently and replaced with a std t-piece(just to keep me going).
Bad!
This sputnik looking doodad is apparently where excess air is channelled into the reservoir tank to be vented(I guess) via the cap.

I think the seam in the reservoir tank is the 'normal' level, but on my last bleed(fixing up my sputnik) I filled it right to the top of the reservoir and it has yet to settle any lower.

I once had a very slight coolant loss(evaporation ??)
my Tdi basically runs at 83°C irrespective of ambient temp.
This one time tho, went camping so loaded to the hilt, with food and kids.
Gravel mountain road, closed the windows air con on.
Almost immediately coolant temp started climbing fast. both AC fans also running(viscous fan hub "may" have been not working properly tho) .. but in no time, coolant temps were up in the low 100s.
Max I saw was 105°C.. I understand that it's technically within specs .. but I'm basically a chicken.
AC off, windows down dusty kids and food :D
I cycled it as I could trying to keep from not going too far past 100°C.
No amount of changing down, going faster, tolling in neutral would allow me to keep the AC going and keep it under 100°C.

45mins later, I idled it for about 30sec, when we got to the other side of the hills, but that was from about 90-ish when we finally pulled up.
Didn't touch the car for a good few hours, so after it cooled, remove cap, no pressure at all and the reservoir was dry.
I filled it to that seam point and it took about 600ml(drink bottle).

No leaks, no steam, no drips, weeps or nothing. Just evaporated.

ps. I did eventually remember to change the viscous fan hub(thanks Roverlord [thumbsupbig]) but that was later in the year, temps weren't in the mid to high 30's.
I have run the AC just to see how it runs. So far I haven't seen above about mid 90's on the digital gauge(VDO sender). So I'm hoping that the camp trip experience was the fan hub, and not normal every day operation!

What bugs me(and every other landrover owner) is, with all that histrionics of heating up(never really overheated as such) is that the stupid dash gauge never moved past it's normal 'just below half way' mark! :bat:

[mattims]

yeah EGT probe is in the EGR blanking plate location. I had always intended to tweak the fuel pump to push it a little more since it only reaches 550 when I really try, but I have just always wanted to resolve other minor issues before make them worse by tweaking the pump.

interesting ... my plastic y join "sputnik" thing was cable tied together when I got the car, but I couldn't see any trace of leaking.

At one of it's services somewhere since I have had it, it has been replaced with a brass t junction. I don't know when.

I wonder if that is a problem.

[workingonit]

You're probably already doing it, but check when system is hot and under pressure (don't risk opening anything). It was the only time I was able to find one particular leak, no green stains to indicate.

Check your reservoir cap. It has 'in' and 'out' valves for pressure management. They can corrode, fall apart and leak lots. Even if not malfunctioning now, but old, changing is a good preventative measure.

Trouble with writing responses is you lose sight of the main thread. If you have changed the water pump then discount the recommendation to check the weep hole located in the underbody of the pump.

[mattims]

had a new resevoir and cap when I bought.. they still look fine not sure how else to test the cap.

and I put a new water pump because it leaked alot out of the weep hole the first time I towed my car trailer. I think my defender dislikes towing the subaru (pretend race car) almost as much as the subaru dislikes being driven to pick up parts for the defender. If only they could both be as agreeable as my motorbike.



You're probably already doing it, but check when system is hot and under pressure (don't risk opening anything). It was the only time I was able to find one particular leak, no green stains to indicate.

Check your reservoir cap. It has 'in' and 'out' valves for pressure management. They can corrode, fall apart and leak lots. Even if not malfunctioning now, but old, changing is a good preventative measure.

Trouble with writing responses is you lose sight of the main thread. If you have changed the water pump then discount the recommendation to check the weep hole located in the underbody of the pump.

[AK83]

...

At one of it's services somewhere since I have had it, it has been replaced with a brass t junction. I don't know when.

I wonder if that is a problem.

Shouldn't be a problem, except like I found out:
In cold temperature it'll take 10 x longer for the engine to get to operating temp due to the design of that sputnik thing.

Got some great advice about it here. On the thermostat hose side of the t junction you insert a small pipe with a tapered end so that it doesn't get pumped through.
The length of that small (internal) pipe should be that it passes the junction where it feeds into the radiator.

This is the bleeder air valve thingy working as it should again.

I doubt it'd cause coolant loss, but my Tdi wouldn't get to it's normal operating temp for at least half an hour or more of freeway driving .. with the fan removed.
It would finally reach it's normal 80-83° but I'd be frozen solid by that time.
I did as was explained, now runs perfectly.

Another point to note about coolant loss, is the wetness/dryness of your front carpets/floor mats.
Could be a heater core coolant loss.
No idea on how easy hard a defer is to get to the heater core.

I know I'd notice the smell of hot/warm coolant inside the passengers compartment.
Sister had a (Ford)Lazer and my ex mother in law had a Sigma, both had that hot coolant smell inside them.
I recommended to both back then to get rid of their respective cars before it cost them to fix it, or the inevitable blown headgasket.

[mattims]

not fully understanding your fix for the T junction, but yes my car does take quite a while to get to temp.

can you explain a bit more on that fix?

might be easier just to fit a new sputnik though I guess, seems like they are not too expensive to get new.


The heater core is not leaking, I have replaced it myself it was bypassed when I bought the car.,



Shouldn't be a problem, except like I found out:
In cold temperature it'll take 10 x longer for the engine to get to operating temp due to the design of that sputnik thing.

Got some great advice about it here. On the thermostat hose side of the t junction you insert a small pipe with a tapered end so that it doesn't get pumped through.
The length of that small (internal) pipe should be that it passes the junction where it feeds into the radiator.

This is the bleeder air valve thingy working as it should again.

I doubt it'd cause coolant loss, but my Tdi wouldn't get to it's normal operating temp for at least half an hour or more of freeway driving .. with the fan removed.
It would finally reach it's normal 80-83° but I'd be frozen solid by that time.
I did as was explained, now runs perfectly.

Another point to note about coolant loss, is the wetness/dryness of your front carpets/floor mats.
Could be a heater core coolant loss.
No idea on how easy hard a defer is to get to the heater core.

I know I'd notice the smell of hot/warm coolant inside the passengers compartment.
Sister had a (Ford)Lazer and my ex mother in law had a Sigma, both had that hot coolant smell inside them.
I recommended to both back then to get rid of their respective cars before it cost them to fix it, or the inevitable blown headgasket.

[AK83]

There is another thread on here somewhere if you can search for it.

but quickly:

if you have a t-piece, the natural way for it to fit is to have the straight end going from thermostat hose to reservoir, and the t junction divert to the radiator hose.
What I was recommended was that the straight section of the t piece, you insert a small diameter pipe into it from the thermostat hose end, flare the end of this small pipe so that it doesn't get pushed through to the reservoir tank.
The flare of the pipe should be just big enough so that it still fits within the hose coming from the thermostat, but not into the t-piece. Only the pipe/tube should fit into the t piece.

Tpiece mod should look something like this:

128327

small red thin part inside is the internal pipe. Note how the pipe extends past the t junction to the radiator(that's the important bit!), and that the other end is flared to stop it pushing through to the reservoir.
I used a small bit of plastic pipe, heated the end and inserted it onto a tapered screw, pushed it while hot to make the flare end.
So far so good, but I have a feeling that if it gets hot, the plastic pipe may soften and push through.

[jboot51]

The vent for release is the expansion tank cap.
My cooling system takes 7kms @ 60kph to get upto operating temperature.
A sneaky leak is the weep hole on the waterpump.
Collant can leak but evaporate quickly, leaving green snot hidden by the pulley.

[loanrangie]

Use a Y piece and you won't have any issues, not sure why you would use a T as it prevents the proper coolant flow.

[mattims]

Well it's been a week and the coolant level hasn't dropped any this week... so it could be a good sign.

I think it may have been leaking at the T that had been installed and it just wasn't noticeable, because all I did was bleed it with the coke bottle method and refit the T piece with mod done.

I used a flared piece of 4mm brake pipe inside the T piece to do the mod mentioned and it does now get up to temperature much quicker (still takes about 5-10 minutes).

So thanks for the help... I'll probably get a proper replacement peice, although seeing as it is a plastic piece that seems to fail maybe my brass T junction is actually more reliable.

[AK83]

.... although seeing as it is a plastic piece that seems to fail maybe my brass T junction is actually more reliable.

That's what I had to hand at the time.
Like loanrangie said, everyone else also recommended a Y junction. I didn't have one, but had the T piece and needed it done.
The mod works, but one day(if I can remember) I'll use a Y junction(brass again) to replace the T.
That pathetic little plastic sputnik broke all too easily. For me, I was undoing the tensioner and slipped on the breaker bar and my arm/hand fell into the spaghetti mess of tubes, pipes and plastic doodads that should have been engineered properly into a less suss location.