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A thermostat that is stuck open leaves you with weak heat and a cold gauge. One that is stuck closed can overheat the engine within miles. Route 66 Auto Repair in Upland replaces thermostats with the temperature rating your engine calls for, fits a new seal, refills with the coolant your engine specifies and purges the air, so you get a steady gauge and full heat.
What are the signs you need a new thermostat?
- Heater that blows lukewarm even after a long drive
- Temperature gauge that rises quickly into the red
- Gauge that stays low on the freeway
- Coolant leaking at the thermostat housing
- Check engine light for a slow warm-up
What makes a thermostat job done right?
The part matters. A thermostat with the wrong temperature rating can make the engine run too cool or too hot, and some have a jiggle valve or bleed hole that must face a certain way. Some engines use a thermostat built into the housing. If yours does, the estimate shows the assembly.
The seal and the fill matter too. A new gasket or O-ring goes in every time. After refill, trapped air has to be purged, or the new thermostat can stay closed because it is sitting in an air pocket. If your engine uses an electronic thermostat or the cause is not yet clear, see cooling system thermostat valve repair for the diagnostic side.
Our thermostat replacement process
Step 1: Confirm the need
We check temperature data and heater output to confirm the thermostat is the cause.
Step 2: Drain and remove
Coolant is drained below the housing, and the old thermostat and seal are removed.
Step 3: Install correctly
The new thermostat is fitted in the right orientation with a new seal, and the housing is torqued to spec.
Step 4: Refill and purge
Coolant is refilled, air is purged, and the engine is run hot to confirm the thermostat opens.
What's included in thermostat replacement
Included on the work order
- 01Temperature and heater output check
- 02New thermostat with the correct rating
- 03New gasket or O-ring
- 04Coolant refill with the type your engine specifies
- 05Air purge and hot run verification
Is a bad thermostat urgent?
Need now: call
- Engine overheating
- Coolant leaking from the housing
Need later: book
- Weak heat in warm weather with a normal gauge
- A slow warm-up code with no other symptoms
How pricing and timing work
Price depends on where the thermostat sits and whether it is a stand-alone part or built into a housing. Some are easy to reach. Others need other parts removed first. Your written estimate comes before any work, and thermostat jobs are often done the same day when the board allows. AAA members get 10% off parts and labor, up to $75. If the housing is cracked, thermostat housing repair is added as its own line.
After the repair
The gauge should settle in its usual spot within a few miles, and the heater should get hot. Check the reservoir cold for a few days. If the gauge moves oddly, call (909) 608-7699 and we will recheck it at the front of the line.
Frequently asked questions
Can I use a cooler thermostat to help in the summer?
It usually does not help and can cause codes and poor fuel economy. We use the rating your engine was designed for.
Should I replace the thermostat with the water pump?
It is often a good time, since the system is drained. We quote it as an option and let you decide.
Why did my car overheat after a thermostat change elsewhere?
Common causes are trapped air, a thermostat installed backward, or a wrong part. We check all three.