I have a 2001 Jaguar S-Type 4.0L. The car is beautiful and runs like a dream, however, the coolant expansion tank will not stay full and always returns to the same level after a top off. Basically the level it resides at is almost the very bottom of the tank, only an inch or so of coolant is view-able in the tank. Questions are:
1. Even though the car runs great and does not overheat, are there any possible issues that could be caused by running the vehicle with the tank in this condition?
2. The heater/AC does not work and just blows outside temperature air, could this be the cause? (Before finding out that my tank was cracked I had blamed the heat/AC issue on the DCCV (Dual Coolant Control Valve) and was getting ready to replace it, but if there is a possibility that this tank is the cause of the issue I would love to know before I got through the hassle of removing the DCCV)

Hopefully someone who knows the answer(s) sees this and replies. Thanks in advance,

Isaac

 

Replace your cracked coolant expansion tank as soon as you can. You run the risk of overheating and destroying your engine until you do. These expansion tanks are a well-known weakness in these cars. The plastic degrades due to age and heat cycles, cracks occur, and leaks ensue. It is not unusual to have to replace these coolant expansion tanks every five years or so....

 

Sounds good. Thank you.

 

+1 (it's a modern alloy heads engine that cannot stand overheating)

 

I replaced mine. the new one cracked too, but this company sent me a free one overnight. Great service.


discountbodyparts.com


part number is REPJ161308 Cost was $88.66


Hope that helps. Be sure you get a new cap too. A bad cap will cause the tank to crack. Caps available at O'Reilly, Autozone, Advance, etc.