why,car temputuer gage goes from normal to hot then back to normal?

Question

i have 2001 jaguar s type if the heater is on off ,the temp gage will go to normal then in a littel while to hot.then if i turn heater on it will go back to normal.if i start with heat on its ok.whats wrong?

Answer 1

I had an AUdi that ran the engine fan when I turned on the fan inside. Could that be what is happening?

Answer 2

The most common time to see this is when a car is driven then parked. The water in the engine absorbs heat from the metal and can not dump it to the radiator, so it gets hotter. When you turn on the engine, the first water to hit the gauge is the cooler stuff in the hoses and radiator then the hot stuff hits and shows a higher temperature (obviously depending on where the gauge is located.)
When an engine first started, no water goes through the radiator to allow the engine to get up to more efficient and clean operating heat. Then the thermostat in the radiator opens to start cooling some water. I suppose it the thermostat was not matched well, the water would get hotter than planned on the gauge, then cool when the radiator came into use.

Answer 3

It sounds like a bad thermostat. When you turn on the heater hot water from the engine flows through the heater coils, allowing more cooling time for the fluid as it travels through the system. With the heater off the water circulates more quickly through the engine and radiator with less time to cool while going through the radiator. The thermostat could be sticking or you may need a radiator flush to remove build up that is partially blocking the radiator. I assume it is not leaking because you didn't mention any leaks.

Answer 4

It could possibly be a bad thermostat, or even more likely a leak in your radiator. For your sake, I hope it is just the thermostat.

Answer 5

Your air valve could be sticking. You should get it seen to as it could potentially blow the head gasket

Answer 6

its probably an electrical problem you should get the wiring checked