When to Replace the Thermostat on your Jaguar.
Your engine is designed to operate within a specified temperature range. If it doesn't get hot enough, the fuel injection system doesn't work right. If it gets too hot, then engine damage occurs. What keeps your engine in the right temperature range? The thermostats. They constantly open and close to moderate the coolant temperature, and when they wear out the engine temperature starts to fluctuate too much.
The two primary failure modes for a thermostat are when it sticks open or sticks closed. When it sticks open, the engine won't get up to proper operating temperature, and when it sticks closed, the engine gets too hot. The only cure is replacement. Fortunately they are cheap!
See our Jaguar Parts Store Catalog to order parts.