Thread: While Head is Off

Originally Posted by justinc

Head gaskets can leak in these at anytime, they just need to get hot and the dowels deform. Pre 2004 they all seem to have plastic dowels. I have removed a couple of 2003 heads to find plastic dowels...

i have 2 in at work at the moment with head gasket failures. Both 2001 models, 1 so bad that the circulation of coolant is almost non existent due to the pressure exerted by leaking compression gasses. When we fitted the pressure tester to the expansion tank and ran the engine, the gauge started to rise by itself even at a cold idle

Basically, there is so much compression gas getting into the cooling system that it is displacing the water as the engine is idling...After about 3 minutes the top hose is empty and the pressure gauge reads 8psi. The water pump has been removed and inspected as I was first suspect of it as there was almost no circulation. The vehicle arrived at work empty of water, I added 10 litres to it to perform a pressure test. I am hoping the head is OK and the block face is alright as the water consists of a brown muddy substance, looks like years without coolant or inhibitor.

JC

these plastic dowels you speak of, are they replaceable with better now or are you up for the same potential short head gasket life span again the second time around (owner of a2001 v8 with a weepy headgasket)

Originally Posted by OffTrack

Like a soft drink bottle - but I'll only talking about after the car has been sitting for an extended period like 6-12 hours.

The cooling system should be a closed system if you don't have leaks. The only pressure you should get in the system is from the expansion of the water/coolant due to heating. That means the once the coolant has dropped back to same temperature as when you last checked there should be no pressure in the system. If you've got pressure under these circumstances it has been added from an external source, and that is usually via the head gasket.

cheers
Paul

Cheers.
I'm not overly concerned it's not really a hiss, sort of a tiny rasp.