DII overheating problems

**Jock The Rock** · 14th January 2009, 02:18 PM

Hey people, I'm Jock's brother and I bought a Disco II Td5 about 4 months ago. The last couple of months it has started overheating and during that time I have had work done on it to try and fix the problem.

Most recently I had the radiator cleaned out (yesterday in fact) only a small amount of stuff was removed, before that the thermostat was repaced and the coolant header tank and cap, all the radiator hoses have been replaced. The water pump is fine as well. I had a pressure test done on it and that came back fine as well.

Maybe i should put that down in order of work done, first it overheated and i got it checked out. I knew there were a few small coolant leaks and so had hoses replaced as were going soft and the header tank replaced because of a small crack.

Still got hot when I got it back, noted change in type of coolant but system had been flushed so I thought should be alright. Got concerned it was a cracked head or head gasket so had the pressure test done which came back fine.

Mechanic suggested process of elimination of header tank cap not sealing, problem with thermostat, or blocked radiator. Have gone through that list in that order with the water pump being checked last of all. Vehicle still overheated after replacing the cap and thermostat. I wont have a chance to drive it for the next 4 days but when the mechanic said the radiator wasn't blocked in a way that could cause the problem I decided getting any info on it would be a very good idea. The mechanic is going to take it while I'm away and see if i'm missing any symptoms (out of work hours so i won't have to pay for it)

Been running water in it because it was pushing stupid amounts of coolant out. The engine monitoring system hooked up to the motor says that the normal running temperature is somewhere between 87 and 95 degrees C

The vehicle tends to overheat when the engine is running at 2500rpm (about 100km/h in 5th) this happens on flat ground. When sitting on 2100rpm (about 90km/h) is fine on the flat but will get hot going up hills. Doesn't like 2500rpm in 4th either (80km/h). Haven't driven it for long enough in any lower gears up hills or on the flat to be able to work out if there is a trend. Speed limit is 50 around town and sits on 2100 in 3rd which it only complains about (gets hot) on long steepish hills. Once the vehicle has returned to a normal temperature and I resume driving those conditions still apply so will be normal temp on flat ground at 2100rpm.

When checking vehicle over while it's cooling down the only thing noticable is where the coolant has been pushed out of the headertank overflow. Nothing from the exhaust or hoses.

So far the only other theories I have heard are the fan belt is slipping, but cant hear it doing that if it is

The vehicle has done 260,000km and ran fine for the first 2 months. It has also been chipped with as far as I can tell a medium performance chip.

Jock is the one who likes messing with motors, I know roughly how they work but am quite happy for someone else who enjoys it more to do the work

Any ideas about what could be wrong with it would be much appreciated. Maybe it's just female but I already thought of that

anyway i'll be away for 3 days so wont be able look at what you come up with until saturday night.

Think that should be enough info, hopefully not to much or that that it's to badly explained

Cheers Nick

**Slunnie** · 14th January 2009, 02:38 PM

When you cleaned the radiator,did you clean the outside of the radiator? The pack with mud and block up. Likewise with all of the other radiators that are in the cluster, especially the transmission cooler.

**bruiser69** · 14th January 2009, 03:07 PM

Hi Nick,

One thing you might check is that all air has been purged from system. There is a plastic purge screw in top hose that you release to remove trapped air.
Be careful though as plastic screw can get brittle & shear off. If it does replace with brass screw & temp resistant Oring to seal.
The other thing that can result in overheating besides slipping drive belt, is viscous fan. These have a bad habit of not locking up when old.
To test it heat hub centre with hair dryer until you can't touch it. You should not be able to rotate blades with your hand if OK.

Good luck..B

**justinc** · 14th January 2009, 03:14 PM

I'm tipping a Head gasket leak Nick, A pressure test etc won't show it up but the only way you can get such a displacement of coolant out of the bottle under load is a combustion gas leak past the gasket fire ring...It is a 1999/ 2000 model isn't it? If so, I would suspect that the head has shifted and the plastic dowels have deformed, causing the gasket to leak pressurised gasses into the cooling system.

JC

**Panya** · 16th January 2009, 04:29 AM

Nick it may be a waste of time but the only time I had a similar problem (albeit only once) was driving the D1 up a long hot hill; at the top stopped to help some friends who had broken down and expansion tank promptly erupted. Nothing wrong with cooling system but the intercooler hose to manifold had not been refitted properly - engine was working much harder than it should have and the result was a much hotter engine; hence the overflow. I hadn't noticed much difference in performance and it was just not fully tightened after a service...

So perhaps have a look round and check that all well will other bits and pieces in the engine bay??

**feral** · 16th January 2009, 06:57 AM

Originally Posted by justinc

I'm tipping a Head gasket leak Nick, A pressure test etc won't show it up but the only way you can get such a displacement of coolant out of the bottle under load is a combustion gas leak past the gasket fire ring...It is a 1999/ 2000 model isn't it? If so, I would suspect that the head has shifted and the plastic dowels have deformed, causing the gasket to leak pressurised gasses into the cooling system.

JC

Sorry Nick but I will go with JC on this one. I have 'been there' and no amount of looking, cleaning, rodding and checking will eliminate the problem.

You need to make the decision now as any further delay could be causing further damage to the head and you do not want to replace that as well.

**Jock The Rock** · 20th January 2009, 05:15 PM

Thanks for the replies

I think Nick is having the head taken off sometime next week

Ill keep you posted

**Bundalene** · 20th January 2009, 07:09 PM

Hi, I had exactly the same thing happen to our D2 6 months ago car getting hot, fluid pouring out of the fill bottle. The problem was a failed viscous coupling on the thermo fan. I had a spare at home - swapped it and all has been good since.

Next time the engine gets hot, try turning the fan - if it turns freely, the viscous coupling is faulty. The fan should be locked up to the pulley when hot.

Erich.

**DiscoJakes** · 21st January 2009, 02:18 AM

I would agree with the fan story.

After similar problems I sat down one day with the rave cd and happened to notice that the thermostat, that was replaced, had the y pipes swopped around. Believe me it can be done.
Have a careful look.... something simple, BUT it did solve my problem of heating when I started pushing the engine a bit harder or towing. It didn't overheat otherwise. Now all is fine again

**Blknight.aus** · 21st January 2009, 06:06 AM

check the VC but I reckon by now even if it was that your head gasket is now on the way.

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