Thermostat Replacement
Also called thermostat stuck
The thermostat is a temperature-controlled valve that keeps coolant in the engine until it is warm, then opens to let it reach the radiator. Stuck closed, the engine overheats quickly. Stuck open, it never reaches proper temperature, so the heater is weak and fuel consumption rises. Replacement fixes those faults, but it will not cure overheating caused by a blocked radiator, a dead fan, low coolant or a head gasket failure.
What the job includes
- Temperature behaviour checked against the gauge and with a scan tool
- Hose temperature comparison to confirm whether the valve opens
- Thermostat and housing gasket replacement
- Housing inspection for corrosion and cracking
- Coolant topped or replaced depending on its condition
- Air bled from the system and a warm-up test performed
Signs you need this
- Temperature gauge rises quickly then keeps climbing
- Engine takes a long time to warm up and the heater stays cool
- Gauge reads below normal even after a long drive
- Fuel consumption has risen with no other change
- Upper radiator hose stays cold while the engine is hot
Not all of these have to be present, and one of them on its own can mean something else entirely. That is what the diagnosis is for.
How we do it
Watch the warm-up
Coolant temperature is monitored from cold to see whether the valve opens at the right point.
Feel the hoses
The upper radiator hose should turn hot suddenly when the thermostat opens; a hose that stays cold confirms it is stuck.
Replace the unit
The thermostat and its gasket are replaced with the correct temperature rating, and the housing is checked for corrosion.
Bleed and verify
The system is bled and the car is run to confirm the gauge settles where it should.
How we work
The same on every job, which is why we can write it down.
Diagnosis before quote
We find the fault first. A price given over the phone for a noise nobody has heard is a guess.
The price is agreed first
You approve the work and the cost before a spanner is picked up. Extra work means another call.
Parts you can check
We tell you whether a part is genuine, OEM, aftermarket or used, and what each one costs.
Old parts returned
Ask and we will hand back whatever we replaced. It is the simplest proof that the job was done.
Book thermostat replacement
Fill this in and a person will call you back to confirm the time and the price. Only your name and one way to reach you are required.
Before you book
Questions we get asked
If your question is not here, ask it. We would rather answer honestly now than have you find out after booking.