I’m thinking the cap may be one of the items very prone to degrading due to heat soak exposure. I make it a practice to leave the hood open after the car has been “out and about” and has returned to its garage. Just trying to get every day of life from all the hoses and plastic bits.


My ‘02 XKR with 166,000 + miles is still apparently on its original expansion tank and original cap. The car came to me with extremely detailed service records, and no I see no mention made of a cap or tank replacement.

In any case, I’ve driven the car 50,000+ miles over the past 38 months of ownership and have noticed nothing amiss with the cap when I’ve had it off.


NOTE: 2+ years ago I removed the under hood insulating pad as it was rubbing and abrading on 2 of the intercooler hoses. It wasn’t sagging, and no amount of “clocking” the hoses kept the pad from rubbing on them. So any heat that the pad was holding in, is now being dissipated more rapidly. The hood exterior paint has not been affected by the pads removal. I didn’t think there would be any issue with the paint as I’ve owned numerous cars that ran way hotter than the XKR , and none of them that had a pad, and the paint on them held up perfectly.




Z