440 TDi cooling problem

[indgepr]

Bit of a problem with my M Reg Volvo 440 TDi, Brief history,

About 6 months ago Cam belt broke and wrecked the head, managed to find a new one that I had skimmed and the garage fitted it with no problems.

Then about 2 months ago Radiator sprang a leak I replaced it and apart from a very slow leak from where the Fan thermostat scews in all fine (will fix when weather warmer as I have to work in the street not fun at this time of year)

About 2 weeks ago driving into work the tem gauge went up as normal then did not stop went on up to horizontal (Norma is between 4 and 5 O clock ) then suddenly dropped back to normal. This happened a couple of times over next few days

I thought that it would be the thermostst sticking so took it into the garage fro them to replace it, but they noticed that there was alot of pressure building up in the coolant and suspected that the head Gasket had gone.

They did a "Chemical" test on the coolant and that came up negative, there is no water in the oil and no oil in the water. I am not convinced that their concerns are correct and that the head gasket is actually ok. Question is what else could be casusing the symtom of the pressureising of the coolant

All sugestion greatly aprechiated

Phil

[indgepr]

another quick question how easy is it to replace the thermostat ?

cheers

Phil

[discover]

Pressurisation could be due to the expansion bottle cap, water pump impeller detached or u/s, thermostat, air lock or the head gasket, worst case cracked head or block (more likely head). Was the new head pressure tested for cracks first before fitting (these Renault diesels are prone to this, ask anyone with a Clio 1.9D) as this is what I would think to be the problem. Is any water being lost? Crucially, NEVER overheat these engines. I've had my 460 ES TD for coming up 7 years and done over 80,000 miles and do trust the car to do anything, but always drive with regular glances at the temp gauge. That said, I never check oil or water between (5000 mile) services, don't even open the bonnet unless the screenwash runs out. That's what comes from being a professional technician, the last thing you want is to work on your own car!

[indgepr]

Thanks for that, think I will try replacing the thermostatfirst seems the easist thing to start with. As it runs fine no oil water mixing and temp stable one stabelised I am hopeing it is nothing more serious. I dont think that the head was cracked when fitted (pretty sure it was not tested ) as it was fine for about 4 months after fitting

Cheers again

Phil

[Chris1Roll]

Did you have the hardened valve seats removed before skimming the head, and then new ones fitted afterwards?

Reason for asking is (VADIS will say the same) you shouldn't skim the heads as the milling tool will ride up over the hardened valve seats and leave a ridge around them, meaning your head gasket is unlikely to seal. I would think doing it with the valve seats out (but this is a nasty job in itself) would be ok.

Second thing, which head gasket was in it originally, steel or composite, and did you replace it with a steel head gasket or the carbon fibre composite one? (and there are three different thicknessess of each)
The head bolts are stretch bolts you see, but the steel head gasket doesn't need extra angle tightening after the engine has run warm, so doesn't make as much use of their "stretchyness" so can _usually_ be reused. I can't remember the maximum length off hand but can find out.


My S40 cambelt snapped on 5th November - bent camshaft - repaired myself with 440TD head. can you tell?!

[Funsport]

Hi

I do not have any technical experience, as per above. And my temp gauge problem did not have a pressurising of coolant, as far as I know.
But, my temp gauge decided to read as overheating. Rescue service assessed that was not actually overheating. My garage decided it was a wiring problem. They resolved the problem and charged accordingly (£600?) for the southern labour cost. No further problem. Except the diesel pump has gone - see my thread.
Good luck - hope you find it more cheaply!

[indgepr]

Thanks for all the assistance, unfortunatly was the head gasket, blew totally, quite impressivly with great clouds of steam out of the exhaust, before I managed to try any of the other fixes

So now have had it done by a more respectable establishment thean the last one

Thanks again

Phil