Just replace them, as well as the plastic thermostat housing. The thermostat is available with the plastic housing assembly with all seals and pipes for a reasonable price. It is all dirt cheap compared to a new engine.

10 years is easily the rated life of the thermostat, the coolant and the plastic housing and the coolant overflow tank.

 

Hi White XKR,
Read my post, link below which I posted recently. Never trust or fit a thermostat without testing it first. This can be done very simply in a pan on the stove, along with a digital thermometer. Also test the old one too to see if it was at fault and remember to ONLY FIT A GENUINE ONE (WAX STAT)

Should start to open slightly at 84 degrees C and fully open by 94/95 Deg C. A torch will help to spot it opening. The one I removed was not opening at all and the alternative stat was opening, but not enough to get that flow of coolant to keep the fans off high, which took about 5-8 Kms to come on though, so was just flowing enough. Just back from a weekend drive and only noted the fans on low or off and driving in 25 degree North Queensland winter. Looking forward to seeing it perform in the 36-40 summers in Dec/Jan


https://www.jaguarforums.com/forum/x...mostat-167409/


Send me a message if you need step by step, as I done the cheap and easy stuff first and some other items which needed doing anyway while the system was open and drained.

Good luck

XKJoe

 

I too would suspect the water pump. I replaced my pump with low miles as reported plastic fins in the pump do fail. My replacement pump has " metal" fins. My xk does the opposite. The faster you go the cooler it gets... 2nd, yes I agree, removal of the thermostat is not a good idea. Some type of restriction is needed to slow down the circulation. Enough time is needed for the coolant in the radiator for the heat exchange. Good luck with your hunt. Rich

 

Hi Gerard,
Like myself, I suspected the water pump too, as I never had any history of it being changed. However, I did perform the test where you remove the expansion tank filler cap, when the engine is cold and then run the engine at around 2000 RPM. You should observe a small steady flow of coolant flow being returned via the small black rubber hoses (8mm I/diameter). If you can observe coolant through the top filler hole returning back, then the pump is usually ok. I could see mine working, but changed it because it turned out to be the black impeller & one piece body original pump. Again, this was not my problem, however I read in lots of places, that these pumps do fail and now its gone and this new one should be good for many years.

If you have not already changed it, it is quite and easy job to remove the pump to check, then refit if the impeller blades are all ok and no excessive play in the shaft or leaks. Just be careful not to lever it off crookedly, keep it straight to avoid breaking the plastic throat.

XKjoe

 

A couple of months back, my wife used my 2002XKR for the day and overheated it on the way home. Coolant tank was full when I got there. Turns out a faulty water pump was the culprit (went 160,000 miles). But I'd change the thermostat at the same time.

 

Overheating Fixed: Jaguar Forum great diagnosis: bad thermostat. Many thanks to Jaguar Forum members especially MrTexasDan for his Coolant Flush, Fill and Thermostat Replacement. Complete with better pictures and more complete procedure than Jaguar's own shop manual.

Thanks again Jaguar Forums