Thanks for all the feedback.
- The temp gauge shows red when high temp comes on, only for 45-60 sec or so and then goes back to the middle
- Have not noticed it going away with the change in speeds or rpm
- when turned on for the first time, the temp gauge stays all the way over to cold before going to the middle after a few minues
-Have a noticed a little bit of coolant on the garage floor (a few drops)

 

Where specifically are the coolant drops what side of the engine bay? You should get this sorted soon runnin that car hot like that is not good for the head gaskets and that will cost you a lot of money. Now let's isolate that leak. Open up your hood check the coolant expansion tank check the octopus hose below that behind the motor. Also check on the front by the thermostat because the water outlet pipe as its called a plastic pipe that's splits two ways are known to warp/crack from heat and leak.

 

Your temp. gauge is not behaving normally. In this case I would suspect the sensor, although the thermostat and pump are still possible.

 

Sorry but his guage is reading normally. The Jaguar temperature guage is a damped switch with three positions, cold, normal and hot where hot usually means the head gaskets will be gone or soon to go. Attach an ELM 327 bluetooth OBDN reader and download Torque to your Android phone and read the real temperature. Better still get a real guage from WhiteXKR on this forum.

Possible issues
Themostat and water pump
If it's an 8 the plastic holder
Duff pipes that expand/shrink
Poor/faulty temperature reader
Faulty fan pack, not switching on when required.

Hope its not been over heating as these cars do NOT like it.

 

All, sorry for the delay in responding - things have been hectic.

Expansion tank, Thermostat, Temp Sensor, several hoses all new. Water pump, Radiator are less than three years old. Body shop has car and says car is not overheating. They drove it 80 miles after checking the wiring and said that the "high engine temp" light never came on.

I now have the Jag dealer and a body shop that specializes in older model euro cars at odds. The body shop seems to think that if there is a leak it may be a a very very small one. They are suggesting trying "Steel Seal" first instead of a head gasket repair.

Any thoughts on these sealer products?

 

There are several valves in the cooling system. I would be concerned that any sealing additive could interfere with correct operation of the valves.

 

+1, find the problem and fix it properly then you can stop worrying.

 

+1, and the heater core is easily plugged. Have you used a test kit to detect exhaust gas in the coolant?