Cooling
What is a Thermostat?
Controls the engine's operating temperature.
Simplified animation — not to scale.
In plain English
A small temperature-sensitive valve in the cooling system that stays shut until the engine warms up, then opens to let coolant flow through the radiator.
A simple analogy
"It is the engine's tap thermostat in a shower — keeps the temperature just right, not too cold and not too hot."
How it works
Cold engine: thermostat closed, coolant stays in the engine so it warms up fast. Hot engine: thermostat opens, coolant flows to the radiator to be cooled.
Signs of trouble
- ⚠Engine running too cold (gauge never reaches normal)
- ⚠Engine overheating
- ⚠Poor heater output in winter
- ⚠Worse fuel economy
Rough UK cost
£100–£350
Parts: £15–£80
Labour: £80–£250
Always get a written quote. Prices vary by car, region, and parts brand.
Heads up: Carautonomy is for general guidance only. If your car is showing warning lights or behaving oddly, get it looked at by a qualified mechanic.