Good afternoon,
My 1999 XK8 convertible and my neighbors 2000 XK8 convertible are both experiencing engine coolant leakage. Both cars have been checked numerous times and the problem cannot be identified. Have any other owners experienced the same problem? We are both at our wits end and do not know where to turn. We both keep adding coolant then it disappears.
Are there any suggestions or assistance out there on the forum that can help our situation?
Thank you in advance for your time and consideration!!

Submitted by Anonymous (not verified) on Sun, 06/11/2017 - 21:38

Hi, I just purchased an 2000 xk8, it was sitting as previous owner didn't drive it much. Well the dash light was flashing engine coolant low, but before it started reading that I could smell it. I looked under the vehicle the best I could and I seen coolant leaking around the mid section of the under carrage. I don't want the auto shop to steer me in the wrong direction. Is there any suggestions what this might be. The water pump is new. So I don't think it's that.

Submitted by SE21-38504 on Tue, 02/19/2013 - 11:16

Edited on 2013-02-19 11:23:40

303-03 26.45.07/20/22 Thermostat Housing and Coolant Return Pipe Removal & Replacement

Symptom: Coolant leaks caused by cracks in the stock thermostat housing, coolant return pipe, and overflow reservoir tank. The original components are made of a composite plastic that appears to be incompatible with antifreeze, causing blisters, swelling, softness, and crumbling. The molded retaining rings that hold the seals in place on the return pipe may break off completely and allow the seals to suck in and deform as the coolant cools down.

Fixit: Replace the thermostat housing with an upgraded aluminum housing kit from an aftermarket supplier. Replace the coolant return pipe with a new plastic pipe (there is no aftermarket aluminum pipe available) and the overflow reservoir tank. Changing the thermostat housing takes about two hours.

Thermostat Housing Rear Bolt Removal: The rear bolts of the housing are under the front end of the intake manifold, and neither 8mm sockets, gear wrenches, or open end wrenches will fit in place or have enough swing room for removal. After removing the coolant return pipe from the front, use a long drift with the edges sharpened to catch the edge of the flared bolt head at a 90?? angle and slowly tap the rear bolts loose in a counter clock direction until removed.

Rear Bolt Replacement: Replace the bolts with hex socket bolts and use a log T-handled hex head wrench to tighten. Using a slightly shorter bolt than the originals will make it easier.

This was from my eexperience with my 1997 XK8, so I do not know during what year Jag may have improved the coolant components. So I hope this helps for those with early XK8's. Good luck!

Submitted by talburkett@gmail.com on Mon, 02/18/2013 - 20:55

I was losing coolant through a crack in my primary coolant overflow tank near the firewall. I replaced it and solved my problem. Run your finger along the bottom of the tank to check for leaks. Can you smell antifreeze after the car is shut down? (it builds pressure)
Just one possible solution.

Submitted by desp8838@bells… on Mon, 02/18/2013 - 20:31

Hello Jean,

Did you both renew the black plastic thermostat housing located on top of the engine?The replacment is in aluminum, so easy to spot. I was addinf ccolant as well an it took me while to find the culprit, the leakage is not evident to see.

Let me know

Cheers

Michel