1997 XK8 Engine fan running on.
 

Once the engine has warmed up the engine fan seems to run very fast and very loud (not vibrating). When I turn the engine off the fan will run on for a few seconds, stop and then come on again for a few more seconds and seems louder than it should. Could this be head gasket issues?

Only if you're unlucky and have seriously overheated it. It's more likely to be a sticking Thermostat causing the cooling fan behaviour.

Graham

+1. Replace your thermostat as soon as possible, and do not drive the car until you do. You are on the brink of overheating.

Thanks
 

Thanks for the advice so far. The temp gauge will only sit half way but if t/stat is sticking, so might t/meter. The ol girl is going in for tensioner change next week and the t/stat will be on the to do list. again thanks.

The temperature gauge is useless. It's designed to sit in the middle of the scale and doesn't begin to move until serious overheating has occurred.

WhiteXKR produces the perfect solution to this with his 'RealGauge' - check the link to his website in post #3 for details.

Graham

Turns out pump impellor worn almost completely away. Original plastic thermostat has slight leak, has been apart and back together at some stage. Plastic ones never seal again as the plastic deforms (I am told) so new Aluminium housing going on. Chain tensioners very worn. Got it in just in time. Thanks for all the advise.