I was taking the jaguar to Maryland on a nice drive 64389 miles and the temperature was fluctuating quite a bit . I do have an Obd mini gauge installed on my dash to see real temperature. I recently changed the temp sensor. Any clues to why this is happening. Thanks.

 

After fully warmed up, what are the temps fluctuating to and from reading on your scanner? Both fans working properly? Debris in front of the radiators?
Seeing as it’s easy, maybe start with a thermostat and gasket change to see if it’s sticking?

 

I will check , temp sometimes going from 203 to 167 to 185 , 197. Fans were working. I will have to check thoroughly.

 

203*F (95*C) is roughly full operating temperature. I wouldn’t get concerned about overheating until about 210*F (99*C). At that time I’d turn the A/C off and heater on full blast. It certainly sounds like you have a sticking thermostat with the low temps going on at times.

 

Thanks I hope I make it back home

 

As long as it’s dry inside the coolant temperature sensor electrical connector and the expansion tank is completely full of coolant, it should be fine. Just continue to monitor the temps.
There’s either three T30 Torx screws or three 8mm bolts that hold the thermostat cover on. If you can park at a steep enough angle with the nose facing up, you might not even lose any coolant. 😂 Ford would probably have the thermostat and gasket in stock.

 

Thermostat is not fully open until 215F on 5.0 cars,

​​​your temperature range seems fine.

 

Seeing as these are 98’-03’ (USA spec) 4.0 V8 cars, these cars aren't used to those temps. 203*F (95*C) is what I see on mine even with the double capacity intercooler radiator and overdriven blower. However, if I lived in the mountains and it was 100*F+ outside, yes maybe it would get to that temperature if I was going uphill with cargo and the A/C on. Fortunately I don’t.

 

Thanks to all when I get home a new stat will be installed