diesel acting weird...

[Adrian D]

Hey guys. i have a 96 xj, 2.5td. from time to time, the low coolant light turns on. when i remove the filler cap i notice an unusual build-up of pressure. there are no signs of leaks under the car after i park it.
i started the engine without the cap and the coolant was a bit foamy. oil looks ok, oil pressure is fine. could is be the dreaded "blown head gasket" disease ?

Sure sounds like it. Have you had it pressure tested?

[Adrian D]

haven't done any tests. i just observed how it acted on a 2200km trip on the highway.
what do you mean by pressure testing ?

[AussieRCBasher]

pressure testing. bascially they take out the glow plug and screw in a pressure guage like for tyres. then crank the engine over and it gives a dialed reading of how much pressure is in the chamber. If its cracked then it will be low in 1 or 2 pots.

Correct me if I'm wrong but the cooling system is what should be pressure tested. Not the cylinder compression. They apply a pressure testing tool to the radiator spout and see if there is a leak somewhere in the cooling system. In your case from the combustion bits somewhere into your water jacket via the head gasket.

[AussieRCBasher]

Yes true, My mate does it the otherway so this stops the water going into the cylinder and hydrolocking the engine incase it is cracked.

[Adrian D]

Originally Posted by AussieRCBasher

pressure testing. bascially they take out the glow plug and screw in a pressure guage like for tyres. then crank the engine over and it gives a dialed reading of how much pressure is in the chamber. If its cracked then it will be low in 1 or 2 pots.

i've seen this type of testing done on dad's vw to check compression.
low in 1 or 2 pots ? can you detail please ?
i still have to learn most of the technical terms. not a native english speaker here but be patient please, i'm willing to learn