The temperatures here in Oklahoma, USA, have been in the mid-100s and the needle on my XJ6's temperature gauge has been running straight up. No problem. But today, the outside air temp is at 109 degrees F and my car doesn't like it. On the highway, she is fine. But in stop and go traffic, the needle is just outside of the red zone. I had to stop once to let the engine cool down. The electric fan works great, and the engine driven fan is good. Anybody have any thoughts on what the problem might be?

 

My first thought is a weak fan clutch. If you don't mind my asking how did you determine the engine driven fan was "good"?

Cheers
DD

 

Ah! Good question. Probably, I should have said that I believe the fan is good. When the engine is running, the fan seems to be running good. How can I tell if the fan is bad, or weak?

 

You might want to put in a flush kit and give the system a good flushing out. After a decade or two crap can build up in the jackets and restrict the coolant flow.

 

In all the years that I've worked on my own cars, I have never flushed a cooling system. Probably because I have never kept a car for more than a few years. I've kept the Jaguar longer than any car except for a Dodge that I had back in the '70s. Is it better to the flush myself, or have it done at a service center?

 

I've always done the job myself. A flush kit is only about $10 or so and pretty easy to install. Being able to see just what gets washed out of the jackets when doing a back flush gives you a pretty good idea what shape the system is in. If you're in an area with low water pressure it is probably better to have a shop do it though.