I have a 2002 XK8 and the coolant light comes on every 3-4 days. The filler container ends up half full, had a compression test done 3 times and they can't find the leak.
I had the same issue with my 2000 XJ8.
Any sugesstions?

 

A proper pressure test kit used correctly should indeed reveal the leak, especially one as draining as yours appears to be. The correct adapter must be used to ensure an air-tight seal into your coolant reservoir. Without a tight seal there, not enough pressure can be generated to expose the leak. Who has been doing your pressure test?

 

Check the valley hoses. Its a hard one to find because the coolant runs across the top of the engine and burns off before it hits the ground.
You will need a pressure tester, a dental mirror, and a flashlight. Check it with the engine cold, then look under the intake manifold. That's where mine was leaking.

 

pressure test is being done by Jaguar specialist

 

You used the word 'compression'. Is your tech looking for a blown head gasket or pressure testing the cooling system? While head gaskets can produce strange symptoms sucking coolant without blowing white smoke is pretty low on the list.

You need a coolant system pressure test.

A common problem with the cooling system test kits usually found for 'rent' in auto parts stores is that they have something like 20 adapters to fit every cooling system in the world . . . but not Jaguar.

You have to use the universal expansion adapter that expands in the neck of the reservoir.

The reason I explained this is that there have been posts regarding people testing the system and not finding leaks because the pressure was escaping into the overflow tube because of an inadequate seal at the mouth of the reservoir due to the wrong adapter being used.

I know you said that the pressure test was done by a Jaguar specialist but you are loosing coolant and a correctly done pressure test is going to show where. And it shouldn't take three times to find the leak. The hoses under the manifold are a difficult leak to find but worst case and most difficult to find is the heater core.

Please let us know how this is resolved.

 

I bought one of these a couple of years ago. The Green adapter works perfectly for my Jag. Worth the investment.
Radiator Pressure Tester Kit

 

I have the same kit. Not cheap, but the quality is better than most people expect from HF.

 

I'd invest in quality tools/testkit anytime as they last a lifetime, like Snap On...

 

Sorry to drag this thread further off the OP's question but . . .

I happen upon an auto mechanics forum focused on tools complete with extensive pictures. One of the posters was a young man in a couple year technical training course where the school provided tool inventory requirements as you progressed through the course work. Many in the class were buying Matco, Snap-On and similar but this fellow was buying Harbor Freight and using their special sales and discount coupons. His total tool investment, including the honking big tool cabinet was less than $3,000 where many of his classmates were spending $40,000.

Now back to the coolant leak . . . .

 

VERY similar kit that I rented from OKI parts here in cincy. Worked on my 03 car. I forget which fitting worked.

 

Hi,
I am just dealing with the same problem.for a long time coolant leaking. ordered new thermostat housing, before fitting it I spotted a leak, almost vapor coming from what I believed was the bottom of the thermostat housing.
messed about changing the housing( those two bolts) and still have the leak. I now think it must be the hoses under the intake, the coolant runs down both sides under the intake manifold.

Steveeasy

 

I had a leak in the reservoir that did not leak or drip but 'fogged' and it was in the field of the plastic away from any seam or mold mark. Showed up in a pressure test as a fog of vapor.

 

Steve,
as you can see from the picture in my post above I went the same route as you. I replaced the thermostat tower thinking that was were the leak was coming from. The leak in the valley hose was tiny and I never was able to see it until I removed the intake manifold. The only clue was the dental mirror I used fogged when I stuck it under the manifold while the system was pressurized.

 

I had the same problem for around 8 months. Always topping up coolant, no drips under car. Took it out two weeks ago, again low coolant, then hot engine temp. Stopped car immediately and let it cool for around 10 minutes. Started it up and bang, the biggest cloud of steam out the exhausts. Head gasket has gone 3rd cylinder on right bank ( makes piston nice and clean). More worryingly was that the second cylinder was almost as bad, took off the left head and the gasket was exactly the same. Hope yours is easier to fix.

 

You all with the valley hose repairs I feel for you if you do it yourself.

 

I'm just about to start rebuilding the XKR engine and I think it would be a good idea to replace the valley hoses while the engine is stripped. Can't find "valley hoses" on any parts suppliers, are they the heater supply and return hoses?

 

I think they are called the heater feed and return hoses.

 

hi,
part numbers in UK are

NCA3945CD
Hose Heater Feed
NNE3946CA
Hose Heater Return

 

You guys need a magic tool like I have. It's about 1/32" thick, 2 1/2" long, and 2" high. The mnfr name is Natwest Debit. I give it the grubby guy in the garage and it fixes the prob while I go to the cafe!

 

With three Jaguars in the stable, it's going to need to be the heavy duty GTI version.

Only things worse in my experience are boats and horses...


M