D5 (D5244T to 2005) Cooling system pressure

[buster1950]

I,v recently sold my beloved S60 D5 (52) & bought an S80 D5 (53) I have a build up of pressure in the cooling system that is still there when cold. Could it be Headgasket or does anyone know of another problem it could be ? It does not have a thermostat at present as the old one was not working, It does not overheat and runs and idles perfectly (not lumpy) Help anyone ?????

[JIM C]

Hello and welcome to the forum.
Hope you get the info your after.

[RoyMacDonald]

Originally Posted by buster1950

I,v recently sold my beloved S60 D5 (52) & bought an S80 D5 (53) I have a build up of pressure in the cooling system that is still there when cold. Could it be Headgasket or does anyone know of another problem it could be ? It does not have a thermostat at present as the old one was not working, It does not overheat and runs and idles perfectly (not lumpy) Help anyone ?????

Cracked cylinder head. Not what you want to hear probably.

I spent over two years asking my main dealer to sort out the over pressure in the cooling system. They always told me there was nothing wrong with it! In the end I went to an independant who said "heads probably cracked, the easiest way so see is whip the head off, it's not a big job" which they did and it had two cracks by then. They got an exchange head from Volvo, good as new.

All the best.
Roy

[buster1950]

Thanks for youtr advice. But how much did it cost ????

[JIM C]

I checked my D5 and have no pressure when the car is cold.

[RoyMacDonald]

Originally Posted by buster1950

Thanks for youtr advice. But how much did it cost ????

It was for the VW/Audi 6 cylinder and cost £850 for the head complete with valves etc and £650 to fit including an new cambelt and coolant. The figures are all with vat included.

That was probably what I spent at the main dealer on new cooling system hoses, seals, and even a replacement for the expansion bottle which cracked under the pressure! Nothing wrong with the pressure indeed!!!

Roy

[buster1950]

Thanks again for your reply. But is there anyone else out there that may have some more ideas or had any similar problems please ?????

[RoyMacDonald]

Originally Posted by buster1950

Thanks again for your reply. But is there anyone else out there that may have some more ideas or had any similar problems please ?????

How bad would you describe the the pressure as being when cold? You do get some pressure when the engine is cold but the coolant level should increase when the engine gets hot and return to the same level every time it gets cold. If your getting raised levels when it gets cold again, water spray from the expansion tank, fatter than normal hoses, the pressure can only come from the engine compression. There is nothing else that can cause it in the cooling system as it is supposed to be a sealed system. Only a faulty head gasket or crack in the head can cause the pressure to stay abnormaly high due to diesel compression pressure raising it abnormally high. You may get a bit of variation in pressure depending on where the crack/fault and which piston is on a comression stroke. Running won't be affected though. Even with two big cracks my engine ran fine. The big danger is if you get enough water into the cylinder to cause a compression lock which will totaly wreck the engine and you won't get any warning until it's too late. So if you suspect you have a leak sooner rather than later is the time to do something about it.

Roy

[buster1950]

Many thanks for taking the time to reply re above problem. The pressure is still there when the car has stood over night,too the extent that some water will be forced out on releasing the pressure cap. There does seem to be air in the system though,could that be a possible cause ???????

[RoyMacDonald]

Originally Posted by buster1950

Many thanks for taking the time to reply re above problem. The pressure is still there when the car has stood over night,too the extent that some water will be forced out on releasing the pressure cap. There does seem to be air in the system though,could that be a possible cause ???????

The system becomes pressurised when the engine is run and always has some pressure in it that is released when you take the pressure cap off. I'm puzzled when you say water is forced out when the engine is cold. I take it you unnscrew the cap slowly and alow the pressure to dissipate before you remove the cap? I assumed you were talking about abnormaly high pressures in the system. You should go by the coolant level. What happens to that? Does coolant spray out when the car is in use? It usually leave residue that you can see on the body work around the pressure vessel.

Why do you think there is air in the system? Any small air bubbles in the system after a coolant change should clear quickly. If the coolant was changed without getting rid of most of the exess air before running the engine hard this could cause local hot spots and crack the head.

Roy