300 tdi Defender overheating ?

[djam1]

Hello
We have a 300 tdi Defender that is in very good mechanical condition apart from the fact that it appears to run warm.
The cylinder head was replaced 2 years ago with a new one, the radiator was renewed 5 years ago and looks perfectly clean internally.
EGTs are not exceeding 550 degrees C, the vehicle runs at GVM, have just fitted a huge electric fan in place of the condenser fan this has been setup with a manual switch, the viscous fan is also only a couple of years old, We recently replaced the temperature gauge with a VDO unit so it should be accurate, thermostat also replaced.

The problem (or is it a problem?)
Today is a nice cool day 28 degrees C a 16 km run with a medium size hill sees the coolant temperature peak at 100 degrees C if pushed it will go up to 105 degrees C.

While I am fully aware that turbo diesels can run at temps up to 110 degrees C safely I would like to think that a Defender wouldn't do this at such a low ambient temperature without towing something heavy.
I personally have a heavily tuned TD5 Defender that has been run all around the country the highest the temp has ever got on this is 98 Degrees C and this was in 45 Degree C ambient temp at over 130 kmh passing a Nissan up a large hill.

I think there is an issue to me its just too close to the edge.

Any ideas

Duane

[AK83]

Thermostat jammed shut or not opening up enough?
I've had my D1 for about 18months now, fitted a temp gauge about a month after I got it. Normal running temps have been about 83-85 everything working well ... no A/C on.

I recently changed my thermostat(mistakenly diagnosed) and while the original Waxstat thermostat did work, it it opened much higher than it's supposed 88°C and when it did open at 100°C(in freshly boiled and topped up water), it barley opened up more than a couple of millimeters.

I got a couple of Tridon thermostats from my local parts store, and the 88° version started to open much earlier, and at approx 88-90°C had about a 10mm or so opening .. far larger than the Waxstat version.

The major difference in how the two react(or operate) is, with both thermostats in the same bucket, I pour freshly boiled water till they're submerged, The tridon starts to open with the water filling the bucket and is fully open before it's submerged.
The Waxstat takes a long time to finally react maybe a min or so after it's been submerged by the boiling water.

I'm assuming that better flow is helping mine now.
I used to get 95-100 temps when running the A/C at highway speeds and on slow twisting steep roads, I've seen 105°C .. had to back off, turn off A/C and managed coolant temp with slowing down A/C off .. etc, prior to changing to the Tridon.
Haven't had enough time to test in the recent 30-ish degree temps we've had if this Tridon actually helped yet or not. But so far it hasn't gone past about 87-89 degrees on the two days I have had a chance to run the A/C on.
We've got a few days of 30-ish degree temps coming so I'll go for a bit of a drive to test a bit more.

Another thing I had to do with all that above was to remove my fan cowling(cos I broke it) .. and that may have helped in some small way too.

The other thing I've changed recently is my water pump(this last Monday).
my normal running temp has been 83-85 on the highway after about 1/2 to 1 hr of running.
Just this morning I did a freeway run, ambient at about mid 20's and my temp maxed at 83(I thought normal) .. but settled back down to 81 towards the end of the freeway drive.
ATM, I reckon the new water pump may also be helping a little now.

[loanrangie]

How is the viscous fan clutch ? - scrap that just read that its fairly new, still worth considering if it was a cheapy.

[djam1]

Interesting point doesn’t one of the falcon viscous fans fit?

[bee utey]

Interesting point doesn’t one of the falcon viscous fans fit?

EA to ED 6 cylinder ones fit clockwise rotating applications, V8 ones fit anticlockwise applications, e.g where a serpentine belt runs smooth side around the fan pulley. The threads match the correct rotation type boss. I've not replaced a 300TDi fan myself but have fitted a Falcon 6 cylinder water pump bearing and drive flange to the front cover of a couple of them, same fan clutch thread.

[Phil B]

X2 for the Tridon thermostat.
Buy an new 88deg version and test in in a pot and boil the water before you fit it.
I've had one that didn't open brand new out of the box.
Phil

[djam1]

Thanks for the replies
I ventured to the nearest town today to be stuffed around by every auto shop at the end of the day I ended up getting the Dayco equivalent to the Tridon TT388-180
this is a 82 Degrees thermostat that fits perfectly .
We had limited success with temps being slightly lower but still up to 100 degrees on some hills not sure if this is normal for a 300 tdi but I know its not for a TD5.
The last thing is the radiator but as I said its not that old and it looks perfectly clean internally.

If 100 degrees is normal going up a hill at 100 km/h I would hate to tow something heavy through deep sand

[AK83]

Did you test the new thermostat to see how much it's opening becomes at 100°C?
If you still have the old one try that as well.

You say you fitted a large thermo fan in place of the condenser(I'm assuming the A/C condenser that is).
If so, then there's no point mentioning a blocked A/C condenser(dirt/build up in the fins).
But what about the radiator? Have you tried spraying it with tap water(not high pressure) just to be sure no grime is blocking it up.

I suppose the other things to look into would be flushing the small hoses. Other than time taken, they're probably worth looking into.
The three small hoses from thermostat housing to bleeder thingie, bleeder thingie to coolant reservoir, and bleeder to radiator.

ps. many moons ago I had an RRC that had hot running conditions. First thing looked at was radiator of course. Just the visual inspection. Looked clean inside and out.
For about 2 years I ran the RRC with the temp gauge(dash gauge) just at the start of the red zone. Gauge and sender were both electrically tested to be OK.
Other than very hot running, it never actually overheated, steamed up or lost coolant .. just ran hot. But I drove it into many trips up into central SA in the heat.
So about 2 yrs later .. or so .. I was mucking about and rubbed my arm hard up on the inside fins as I slipped and the fins crumbled, almost into dust. No leaks and whatnot .. just looked pretty sad.
So I sourced a new rad .. and wouldn't you know it .. the temp gauge settled to normal temp operation!.

Like you said tho .. it can probably take that kind of operating temp for a while .. but you wouldn't want it to for too long.

Try running it without the fan shroud for a run to see if it makes any difference, either hotter or (hopefully) cooler.
I'm guessing that any difference could be a clue as to where to best direct your efforts.

[PAT303]

Interesting point doesn’t one of the falcon viscous fans fit?

Yep,been running one on my Tdi for over 15 years. Pat

[djam1]

Thanks
Hoses are OK and we vacuum filled it so air blocks shouldnt be an issue
Will recheck the cores but am confident they are OK
I guess the next step is a new radiator but I am not convinced that this will resolve the issue as the existing one isnt that old and its a 4 core unit.

I have spoken to a specialist in Adelaide that suggests that we try a thinner radiator as it will dissipate the heat quicker personally I am not convinced.



Did you test the new thermostat to see how much it's opening becomes at 100°C?
If you still have the old one try that as well.

You say you fitted a large thermo fan in place of the condenser(I'm assuming the A/C condenser that is).
If so, then there's no point mentioning a blocked A/C condenser(dirt/build up in the fins).
But what about the radiator? Have you tried spraying it with tap water(not high pressure) just to be sure no grime is blocking it up.

I suppose the other things to look into would be flushing the small hoses. Other than time taken, they're probably worth looking into.
The three small hoses from thermostat housing to bleeder thingie, bleeder thingie to coolant reservoir, and bleeder to radiator.

ps. many moons ago I had an RRC that had hot running conditions. First thing looked at was radiator of course. Just the visual inspection. Looked clean inside and out.
For about 2 years I ran the RRC with the temp gauge(dash gauge) just at the start of the red zone. Gauge and sender were both electrically tested to be OK.
Other than very hot running, it never actually overheated, steamed up or lost coolant .. just ran hot. But I drove it into many trips up into central SA in the heat.
So about 2 yrs later .. or so .. I was mucking about and rubbed my arm hard up on the inside fins as I slipped and the fins crumbled, almost into dust. No leaks and whatnot .. just looked pretty sad.
So I sourced a new rad .. and wouldn't you know it .. the temp gauge settled to normal temp operation!.

Like you said tho .. it can probably take that kind of operating temp for a while .. but you wouldn't want it to for too long.

Try running it without the fan shroud for a run to see if it makes any difference, either hotter or (hopefully) cooler.
I'm guessing that any difference could be a clue as to where to best direct your efforts.

[AK83]

Well there goes that idea!
There's a bloke in Bendigo that makes up 4 core copper rads for the D1 .. had it in mind to try to get one for mine considering the heat mine generated with the A/C on last summer.

I would have thought with a 4 core rad .. you'd be hard pressed to be getting any heat in the engine.

Apart from a possibly weak water pump(ie. broken impeller blades or some such thing) .. I'm out of ideas for 'ya.

[mox]

When changing the timing belt on my 300Tdi Defender 10 years ago, I removed the air conditioner condenser and bought one to fit which only goes in front of the radiator and NOT the intercooler, which works better with a stronger flow of cooler air. This condenser has coarser fins, which would be less efficient than the original Australian fitted one when clean but less prone to blockage and easier to clean . However, fitting has not yet come to top of priorities. Intend modifications including flexible hoses to allow it to swing forward for cleaning it and radiator core.

Meanwhile, I have left off the shroud and the viscous fan is stored behind the seat in an extended truck cab in case needed. No electric fan in front of radiator either. There was a small one in front of original aircon condenser. Seems to me that electric fans are partly self defeating. Initially need switching on because when off they are significant wind obstructers.

Have cut vent holes in guards on both sides so air from engine compartment can get out other than down sides of motor and under vehicle. Installed 105 degree temp sensitive switch on cylinder head and wire to fuel cutoff on injector pump goes through it. Have had motor stop and I put viscous fan on three times in 115,000 km. but have been careful to avoid prolonged idling while stationary in hot weather. Once after a common problem - the original radiator header tank split, once with heavy buildup of overripe wild oats on front of radiator core while driving through a tall "crop" of them in paddock and once pulling loads offering very high wind resistance on both vehicle and trailer. Think latter would not happen again in similar conditions as since both guard vents have been enlarged.

Vehicle has its original radiator and intercooler. However, reckon my intercooler would work much better than with the standard setup. Probably much more cooling air going through it than before, which then cools left hot exhaust side of motor. Also drilled some holes to let air through webbing in aluminium above water pump, which cools exhaust manifold a bit. Have not yet got around to doing "tropical mod" to standard radiator. Note water from motor enters radiator on top LHS. There is a baffle half way down the left side tank. Water goes from left to right, down the right side tank and back to the bottom left one to which to bottom radiator hose is connected. For a reason something like making the radiator less likely to bust if it freezes, there is a hole of about half an inch in diameter in the baffle plate in left tank which allows some hot water to recirculate rather than go through core. Common practice in Australia if tank is taken off for "rodding" clean is to block this off. Mine has not been off. Am considering making an aluminium conical plug with piece of long stainless 6mm threaded rod to put in via half inch BSP plug hole at top.

To me it seems Land Rover engineers have designed an aerodynamic abomination with the cooling system airflow on 300 Tdi's. Lots of junk to obstruct air flow and looks to me that front of the fan would suck air from the intercooler while back would blow much of it back again into the badly designed shroud.

My comments may not have helped diagnosis of the overheating problem described. However, it seems others having them often try fitting more fans and better radiators and intercoolers when lack of capacity of standard ones should not be a problem with adequate airflow and coolant circulation. Details of the latter need looking at closely.

[Michael2]

Have cut vent holes in guards on both sides so air from engine compartment can get out other than down sides of motor and under vehicle.

I don't have overheating issues, but I put a vent in the LHS guard to improve airflow and wash away exhaust heat from the firewall. It has dropped EGTs by 50.C at 100kph on a warm day by increasing airflow through the intercooler. It's hard to measure cooling effect on the radiator, as the thermostat plays a buffering role in that equation.

As for the overheating diagnosis, can you get a laser thermometer at Jaycar or ebay and double check that what your guage is telling you corresponds with the radiator temp? It could just be your gauge or sender unit reading high.

[AK83]

...
As for the overheating diagnosis, can you get a laser thermometer at Jaycar or ebay and double check that what your guage is telling you corresponds with the radiator temp? It could just be your gauge or sender unit reading high.

I suppose that's another point to contend with ...
What location was the VDO gauge placed at?

On my 300 Tdi I used a brass replacement plug for the bleeder plug on the top of the thermostat housing. Brass plug has a 1/8th NPT port where I attached the VDO sensor.
So my coolant temp readings are right at the thermostat.

I've used my IR temp gauge to check temps around the head, and there are some hot spots here and there, overall tho it syncs nicely with what the VDO sender unit is showing.

Then there's the question of whether the VDO temp gauge has been matched to the sender unit.
ie. was the gauge and sender unit purchased as a kit, or separately.
If separately, is there any chance that the gauge may be a 50-150°C type and the sender unit possibly a 40-120°C type.

[SSmith]

the viscous fan is also only a couple of years old


I had one fail after only a few months, for the sake of the ole paint brush test I'd be sure before moving on to more expensive things.

[Red90]

Normally gauge problems are due to a problem in the wiring. It does not take much of a bad connection on the ground side to make it read high.

[djam1]

The new VDO gauge has the correct sender and is located where the original sender was
Laser thermometer confirms operating temps

[edddo]

Curious as to why you think removing the shroud would make the engine run cooler?
Is this specific to defenders or disco's as well.




Did you test the new thermostat to see how much it's opening becomes at 100°C?
If you still have the old one try that as well.

You say you fitted a large thermo fan in place of the condenser(I'm assuming the A/C condenser that is).
If so, then there's no point mentioning a blocked A/C condenser(dirt/build up in the fins).
But what about the radiator? Have you tried spraying it with tap water(not high pressure) just to be sure no grime is blocking it up.

I suppose the other things to look into would be flushing the small hoses. Other than time taken, they're probably worth looking into.
The three small hoses from thermostat housing to bleeder thingie, bleeder thingie to coolant reservoir, and bleeder to radiator.

ps. many moons ago I had an RRC that had hot running conditions. First thing looked at was radiator of course. Just the visual inspection. Looked clean inside and out.
For about 2 years I ran the RRC with the temp gauge(dash gauge) just at the start of the red zone. Gauge and sender were both electrically tested to be OK.
Other than very hot running, it never actually overheated, steamed up or lost coolant .. just ran hot. But I drove it into many trips up into central SA in the heat.
So about 2 yrs later .. or so .. I was mucking about and rubbed my arm hard up on the inside fins as I slipped and the fins crumbled, almost into dust. No leaks and whatnot .. just looked pretty sad.
So I sourced a new rad .. and wouldn't you know it .. the temp gauge settled to normal temp operation!.

Like you said tho .. it can probably take that kind of operating temp for a while .. but you wouldn't want it to for too long.

Try running it without the fan shroud for a run to see if it makes any difference, either hotter or (hopefully) cooler.
I'm guessing that any difference could be a clue as to where to best direct your efforts.

[AK83]

Curious as to why you think removing the shroud would make the engine run cooler?
Is this specific to defenders or disco's as well.

Only because I cracked mine and it won't sit securely now.. so I've been running my D1(300 Tdi) without for a couple of months now.
It's certainly not heating up in any way, and in fact seems to run cooler in many situations(ie. sitting in traffic, fan removed .. etc.)

My real test tho is when we get any over 30°C days and I run the A/C.
Last summer I've seen hotter coolant temps with A/C running.
Whether this is due to the extra load that the A/C compressor needs(unlikely) or more to do with the additional heat from the condenser(more likely) getting passed through to the rad .. I'm not yet sure.

But with A/C on(last summer) on a hot day, I used to see high 80's coolant temps sitting in slow traffic, but as the traffic clears and I'm up to more like 80-100 k/h coolant temps rise(to low to mid 90s).
Makes no sense to me for mine to run this way.
The only time I've had cause for concern was on a couple of slowing drives, on slow gravel roads some steepish, where coolant temps exceeded 100 with the A/C on .. and I had to manage it.
Normal operating temps without A/C on are low to mid 80's(ie. 83-85 ish), even in hot weather. Even in claiming that, the 85°C temps are only momentary spikes(less than a min) and it always settles back to 83.

In the past month we've only really had 2 days of hot temps(30+) and both days on the freeway run home with A/C on max coolant temp at 100k/h has been 85°C(after about 10 mins).
On those days back in Oct the only two changes I'd made to the cooling system has been (first) the broken and removed shroud, and then the change from the old waxstat thermostat to the better flowing Tridon(both 88°C types).

[edddo]

Gday Aurthur
Ok that makes some sense then.
I would just about gaurantee that low range hilly 4wding on a hot day would highlight why the shroud is a good thing.
But i wouldnt mind being proven wrong.
I am considering geting my original radiator rodded again (maybe recored) and this time add the tropical mod ..it has alway shown creeping high temps (up to 100 on the head sensor which probably means 105 to 110 coolant temp) in extreme heat when working.
Owise 80 to 85 is typical.

[AK83]

Gday Aurthur
Ok that makes some sense then.
I would just about gaurantee that low range hilly 4wding on a hot day would highlight why the shroud is a good thing.
But i wouldnt mind being proven wrong.
....

Last weekend ended up at Murray Sunset NP.
The bulk of the trip in and around the park was easy gravel tracks(ie. non 4WD) but there was also some deep sandy tracks to play in.
The 30-ish k drive up to Mopoke Hut didn't cause any heat build up, and the sand dunes were what I would describe medium. ie. not too hard but definitely 4WD and I set to low range too. Brother drove most of the tracks so couldn't really tell how hard(or actually soft and boggy) they were.
Was too lazy to lower tyre pressures too(have compressor, but I only a portable Chinese cheapie which takes forever to do it's thing). So poor little D1 struggled more than it should have in the sand.
On the way back tho, I drove out and we took an even harder track .. sand dunes were much harder, low ratio again. Hit one (the last one) dune at about 40k/h(remembering that tyre pressures were still highway level, and she got bogged.
Struggled to reverse back too(steering more than bogging) to line it up again and choose a different line. Had to hit 60k/h at the base of this dune, feathering and pushing throttle to get over. Made it at a very slow walking pace by the top of the ridge and had it been a couple more meters higher would have got bogged again.
Of course lower tyre pressures would have allowed fuss free movement, but were were only 30km from the end of the park where the smooth gravel started again.

Most of my efforts were focused more on the coolant and oil temps, rather than the track and getting over the dunes in one go(should have let brother drive :p).
Coolant temp never budged from it's 83, oil temp did creep up from a normal 60-ish to about 70-75. By the time we hit Ouyen 50k later I noticed oil temp back down to 65(coolant still at 83)
My guess is that engine struggled a bit more than I thought it was(I feel less feedback from an auto than a manual in these conditions).
My sand driving style is more 'feather and push' as needed rather than the typical push hard, hard charging style I've seen from many others.

At the risk of taking the thread off topic, what happened next was that at some point between mopoke/Ouyen and home, stupid harmonic balancer started coming loose again(2nd time). Don't remember hearing it at Ouyen, and not once on the drive home.
Loose balancer then took out the alternator pulley(completely loose) and must have stressed the water pump shaft as it was leaking out of the weep hole.
So at some point, the poor 300 Tdi also had to deal with this issue as well .. just don't know at exactly which point it started(ie. in the N.P, at Ouyen, or on the easy 5 hr drive home from up there).

Stupid me tho .. these dunes would have been an ideal test to see if the coolant still heats up as it used too with the A/C on.

The replacement waterpump I was advised by the parts chap was a ProFlow branded one. My only request was that it not be a cheapie .. just a very good one. That's what he sold me.
Since the new pump change, I now notice that (with all the other changes/mods) the coolant now seems to be happier at about 80 or so .. dropping to 79 too in traffic(and as a test without fan).
It peaked at 83 briefly(a few seconds) but then dropped again on this test run.
Old pump seems to have the exact same impeller blades as the new ProFlow type, and other than the small drip from the weep hole it was otherwise in good nik and clean

But, yeah .. have it in the back of my mind to keep an eye on it if we hit any harder tracks or steepish hill climbs.
Had plans to do a short drive into some hilly country today, but another curve ball was thrown my way .. dad's Exploder did a clutch so had to orgainse some transport for him while we work out what to do with that now. [bighmmm]

[djam1]

For the benefit of those in the future

We installed a Dayco Thermostat DT50A 82 degrees C
The tropical modification for the radiator (partially blocking off the half inch bypass hole in the radiator) for reference as a proof of concept we used a tubeless valve stem that had been shortened and the valve removed pushed on a piece of rod into the hole.
This will be soldered up in the future apart from a 2mm hole

The end result is its much better probably 5 degrees cooler on average

Ongoing testing will be done next week when the vehicle is used out bush.

[AK83]

Good to hear.

On my drive yesterday I think I've had a bit of success with my hotter running 300 TDi with A/C on too.
First true test with A/C on and >30°C day.

Before I did anything to my 300 Tdi(other than a service) with A/C I'd get low to mid 90's with A/C on on a freeway run, and in slower moving traffic high 80's to very low 90's.
ie. as engine load and speed dropped, so did operating temps with A/C on. Without A/C .. coolant temps barely moved from 83°C

Yesterday my run had a very slight incline at 80k/h. Tdi struggles up this incline in top locked TC. It maintains 80k/h but can't accelerate unless I slow a little to allow TC to unlock or drop to 3rd.
I wanted the loaded engine condition.
coolant temp peaked at 90 dropped back down tho to about 87 before I hat the high point. A good sign.
I'm thinking that the freer flowing tridon(88°) is definitely helping.
In the 80k/h zone on the freeway it sat between 86-91 or so .. also a better result from the previous steady 90-94 or so it used to hold.
in the 100k/h zone of the run and a few hard acceleration moments I tested .. max temp was a brief 94, but always dropped back down to about 87(sometimes 86).
It seemed to hold 88-90°C for a short while, and always dropping back to 86-88°C
So I'm thinking that the freer flowing thermostat is definitely helping coolant flow between engine and rad .. for sure.
Previously it'd hold the low to mid 90's and only drop after a slowdown/ease off period.
Now it's appearing to react quicker to how (I think) the thermostat is operating.

No idea if the lack of a fan shroud is making any difference .. but it certainly isn't hurting.

I'm going to try to check if this bypass hole in the rad is still there in mine too.
Is it easy to see from the fill plug?

[swivelrat]

Interesting read considering my 95 TDi Defender 130 is still getting warm on Greenmount, Perth every arvo and with summer looming again, I would like to investigate further. With a new Tridon TS, new pump, rad, hoses, viscous and electric condensor fan getting me though last summer, Im guessing this air flow idea has merit though Im not that keen on chopping the guards up just yet. If I have a head wind, its notably a harder climb but a cooler temp although warmer than usual. Tailwind up the hill results the highest temps guessing due to less air flow. There's no doubt that the hill is a dam good test of the little 4cyclinder, and it has done it without a hitch every arvo, for over 6years.

However, I'm still not convinced that landrover had the right idea of taking water from the head for the heater but then dumping it in with the cooled water ex radiator/pre water pump. For this reason, I regulate an increasing engine temp with heater, last course of action Im afraid, plus AC fan with no compressor so as to activate condensor fan.

So far the engine temps have never reached the red, only 3/4s of the black. Interesting thing is that using a IR temp gauge, when the dash gauge is showing 3/4s, the temp on the thermostat housing shows 88deg howvever, the temp of the bottom hose going in to the pump shows 94deg?? Im guessing this shows actually how much the ex heater/head coolant rises the already cooled water from the radiator too before re-entering the motor. Im thinking of blocking it off but someone on here said dont last year so stuffed if I know. Maybe this is Landrover's smart way of cooling a hot part of the head, although they could've dumped it into the top hose which Im thinking of doing.

Im thinking first job is to get coolant tested for exhaust gasses, if none then will add additional temp gauges, then progress with the chopping of side panels though I might remove spotlights first. Any ideas.

[Red90]

Your description is a viscous unit not locking up.

[swivelrat]

Thanks for the input but I thought the same so I bought a third vc fan but no difference. I can hear it drawing when warm but I will try the paint brush test as Im not keen on fingering it. Just to be sure, I will take the spare and see if I can lock it up manually then fit it to see if any difference, wouldn't hurt.

[curnowdj]

If it is not using water then I would be looking at thermostats as suggested.
I had a interesting experience with a 300TDI head replacement a couple of years ago. I fitted the new head as per manual but found it used water and overheated almost straight away. What I found was when doing the first head bolt tension(40nm) I think. The first round all bolts came up to the 40nm but then I rechecked by going over head bolt sequence again and found the middle bolts went up more. I did the tension sequence another 4 times before all head bolts came up to the 40nm. No more using water after finishing tightening down head completely. I think that may be a reason for head gaskets failing between no2 and no3 cylinders.

[grounded]

I would never let a diesel run to 110 - nothing safe about that. One bizarre problem i had with an overheating engine once was simply the water pump blades had corroded away so although everything looked fine, new radiator n hoses etc etc etc - it was an internal problem. Nothing to do with airflow :-/

[djam1]

I would never let a diesel run to 110 - nothing safe about that. One bizarre problem i had with an overheating engine once was simply the water pump blades had corroded away so although everything looked fine, new radiator n hoses etc etc etc - it was an internal problem. Nothing to do with airflow :-/

I agree and am equally as wary interestingly the TD5 ECU when the coolant temperature is at 110 Degrees C there is no De-tuning not until 115 -120 Degrees C

[PAT303]

Thanks for the input but I thought the same so I bought a third vc fan but no difference. I can hear it drawing when warm but I will try the paint brush test as Im not keen on fingering it. Just to be sure, I will take the spare and see if I can lock it up manually then fit it to see if any difference, wouldn't hurt.

Mine's driven up green mount many times without the temp spike your describing,in two weeks actually as I'm working in Laverton Hospital for a month. I'd be removing anything that blocks airflow from the front of your vehicle and try again.Are you going up in fourth or fifth?.

[curnowdj]

With all the things done to solve this overheating problem would injection timing have any influence on this? I guess the only way to check is to physically look at the timing belt to make sure all timing marks line up.

[swivelrat]

Timing is fine, have just changed belt etc, but no change in getting warm. Doesn't seem to matter, fourth or fifth gear, still climbs at to the 3/4 mark sitting on 85-90kmh.

Summing it up, I have replaced everything to do with the cooling system, even the heater element, but no change to the symptoms. I will test the coolant for exhaust gases though it doesn't use any coolant so cant be anything major. Will install a more accurate temp gauge and monitor.

I'm pulling the engine out this weekend to replace clutch so a closer look at air flow will be good.

Cheers

[edddo]

For the benefit of those in the future

We installed a Dayco Thermostat DT50A 82 degrees C
The tropical modification for the radiator (partially blocking off the half inch bypass hole in the radiator) for reference as a proof of concept we used a tubeless valve stem that had been shortened and the valve removed pushed on a piece of rod into the hole.
This will be soldered up in the future apart from a 2mm hole

The end result is its much better probably 5 degrees cooler on average

Ongoing testing will be done next week when the vehicle is used out bush.

Seems like a good result. Can you tease out the individual effects of the new thermostat and the modded radiator?

Just re the tubeless valve stem - I assume you had to pull the radiator apart to fit that? If not can you give more detail on how you did that please?

[djam1]

To be honest I cant let you know what the individual effects were as it was a little unclear specifically what had the greater effect.
We installed the tubeless valve stem by forcing a piece of rod in the bulbous end and pushing it into the hole in the divider tank through the filler plug at the top of the radiator. Read the valve stem goes down and it clips into the hole perfectly the rod was then pulled out.

My gut feeling is that the tropical mod had the greater effect I haven't heard from the driver since he left so am not sure what is going on with it now.


Seems like a good result. Can you tease out the individual effects of the new thermostat and the modded radiator?

Just re the tubeless valve stem - I assume you had to pull the radiator apart to fit that? If not can you give more detail on how you did that please?