Postby ptjs1 » Sun Jan 13, 2008 4:24 pm
Gordon,
It's generally agreed that white gunge is caused by water mixing with oil and, therefore, typical of head gasket failure. However, you can get moisture caused by rapid cool-down of an engine. For example if you've done a recent number of short journeys after the car has been started from cold. Does this sound likley? Try cleaning out as much of the gunge as you can and do a couple of long runs. You might find the problem has gone!
If unfortunately you have got head problems and you've got water coming from the cooling system, you might also have oil getting into the coolant. Take off the header cap (when the engine is cold) and see if you've got a rainbow-like effect on the surface of the coolant, which indicates oil contamination. Also, try starting the engine with the cap removed and see if you get small bubbles rising to the surface of the coolant soon after starting, as the head gasket leaks allows pressurisation of the coolant.
Good luck, Gordon, let's hope it's not bad news.
Paul
1995 XJS 4.0 Convertible
1980 XJ-S Pre-HE
Jaguar 4.2 Supercharged engine (but not with a Jaguar body..)