Gents,

Now that the weather is cooling off for autumn here in the Midwest, I've noticed that my XJR takes a rather long while for the coolant temp gauge to get up to the normal mark. My heat seems to be fine, although it hasn't been cold enough to need it full blast yet. About the only time the gauge will get to normal is after I've shut it off and let it "heat soak" for a while, then it's back to normal....until I've gotten back on the highway where the gauge will fall from normal about 4-5mm below that. Think I have a failing stat?

Thanks all!

 

that does seem odd, my car gets to operating temp within 5 minutes of startup

you should consider getting a "realguage"

 

Could be the thermostat, or maybe the sensor. Try disconnecting and cleaning the plug first.
RJ_________________
97 XK8 86K mi

 

Probably the thermostat sticking open, I have had that on my Jag and a couple other cars. It's cheap and easy to change.

 

+2 on stuck thermostat - My Jag at full operating temperature within 5 minutes of engine starting..

 

Thanks fellas; and you say full temp within 5 minutes even in cold weather? As when its warm out, my car is probably at full temp within about 5-7 minutes as well.

 

These engines are made to warm up quickly. The engine water jacket doesn't hold a lot of coolant and it's supposed to warm up quickly to cut down on wear - at least that's what I've read. Thermostat sticking open sounds like a good bet.