There are several XK8s advertised with blown head gaskets, fromm1999 up. Is this engine prone to head gasket issues
Or is it likely being misdiagnosed?

 

Blown head gaskets do not seem to be an issue in the 4.0 engines. The issue is the original timing chain tensioners which were constructed primarily of plastic. They tend to grenade and destroy the 4.0 engines. The general recommendation is to replace them with the third-generation tensioners as soon as you discover this job has not already been done....

 

It's not really common, and usually caused by overheating due to coolant loss. The temp gauge sits mid-scale, then suddenly climbs to the red at about 230 F. Drivers often think they can get to the next exit or even home, but it doesn't work that way.

 

Head gasket failures on the AJ26 or AJ27 are usually caused by the engines being severely overheated.