I've had my 2002 xk8 for about 6 months and Donna ton of work on it. Both cosmetically and mechanically.
As far as the coolant system, I've replaced the thermostat, housing, plastic intake manifold several hoses, expansion tank, 3 way connector below throttle body, several clamps but I STILL can't find the source of the smell. It has improved a lot as most of the things I replaced were leaking/weeping coolant.
I've cleaned all residue off everything that could burn off, and after a couple weeks, I would think it would be gone by now. It seems to be the strongest around the expansion tank area. My mechanic and I have looked everywhere for signs of leaks but can't find anything left. He's pretty sure it's not in the heater core as I don't get any smell or moister through the vents, like I did on my old x-type.
Do I just live with it at this point??

Submitted by philliphefner@… on Mon, 03/31/2014 - 09:21

we've literally replaced every hose, expansion tank, housing, everything. I still get a faint smell but it did improve some when we replaced the valley hoses in the block. Although there were no visible signs of leaking there. I've made peace with it since the level isn't changing.

Submitted by riscoe@cox.net on Sun, 03/30/2014 - 22:46

Phil- I have intermittently been smelling occasional coolant in my 2003 XK8. Recently a detectable leak developed, which I traced to a leaking header tank. I"m hoping a tank replacement will solve it. Where did you get your tank from? There seems to be many different applicable part numbers/manufacturers out there. Did it come with the level sensor? My sensor died a while back, so I jumpered the connector to turn off the low coolant message, but now that its time to change the tank...

Submitted by No1inTex@verizon.net on Sat, 06/22/2013 - 23:18

Phillip,
Try a new seal ring on your expansion tank cap. I had the same problem ant told my mechanic. He performed a pressure test first. There were no apparent leaks. Then he replaced the seal ring and that cured the problem. This may be worth a try.
Good luck,