Jag XK8 loosing coolant

[Laurence1962]

Hi, my first time here so go easy! I did a search without success so here goes.
My 2001 4litre XK8 started loosing coolant last summer, local garage wouldn’t touch it even though the leak was visible at the engine top front and then appeared to be running to the back of the engine and pooling. I took it to my nearest private Jag specialist (35 miles away) who diagnosed the leak and replaced the water pump.After less than a100 miles, warning light comes back on and it needs coolant. Took it back, they can’t find a leak and I can’t see one. They suggest an airlock and it will self bleed out. Well 500 miles later is hasn’t. I’m hesitant to take it back and don’t really know what do, the oil is fine not emulsified and I still can’t see a leak, very grateful for any thoughts or advice

[Luxobarge]

I have the exact same car, but have never had any cooling problems so can't really help from experience. However, check the carpets and underlay in the footwells very thoroughly, as a heater matrix leak can take a long time to become evident, as the underlay can soak up large amounts of coolant.

Having said that, general experience would tell me that if the original fault was definitely the water pump, then it's likely that the fault still lies in that area. Do you have a cooling system pressure tester? If not, they can be a useful tool to have, or you could try to make one. Pressurising the system and investigating thoroughly is often the way to go, if you do it when cold then the coolant won't evaporate away.

Will post back if I think if anything else....

[Laurence1962]

Thanks for your response Lux. But carpets are bone dry. Let me know if you hang further thoughts
Cheers
Laurence

[Laurence1962]

I’ll also get a pressure tester

[suffolkpete]

You could get one of those testers that test for combustion gases in the coolant, they consist of a blue liquid that turns green if combustion gases are present. I don't know if these cars are prone to head gasket failure but they only cost a few quid and may set your mind at rest. The oil doesn't always get emuslified, excessive steam from the exhaust is another sign,