Q: Temperature spiking up after I changed my thermostat trying to get my heater to work.

asked by on

There was nothing wrong with the original thermostat but I wanted to start at step one to see why my heater was not getting hot. I changed out the thermostat and after about 20 minutes of driving the temperature starting rising. I had the radiator flushed thinking I had some air in the lines. After that didn't work I put the original thermostat back in because it had no issues. The temperature is doing the same thing now, what could be the problem? Also nothing is leaking!!

My car has 134000 miles.
My car has an automatic transmission.

The heater not working in some cases may be related to the overheating problem you are also having. This may be due to a faulty heater blower motor or potentially a bad heater core. As you know, the heater core is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. When the cooling system is not properly circulating coolant through the motor, this results in the warm coolant not being pumped through the heater core properly in order to warm the inside of the vehicle.

Engine overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. As mentioned above, this also restricts the warm coolant from flowing through the heater core which uses this to blow warm air into the cab of the vehicle. I would suggest having an expert from Your Mechanic come to your home to diagnose your cooling system.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Temperature spiking up after I changed my thermostat trying to get my heater to work.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Truck is overheating and the heater is blowing cold air.

Hi there. There is a blockage in the engine preventing the engine from cycling the coolant. If there is a new water pump and a new thermostat, then the coolant should be cycling. Check the radiator for any blockages. Drain...

Q: Car overheating; thermostat

Hello! A common reason for most vehicles to overheat is a faulty thermostat. However, on 350Z's, the factory fans are known to fail prematurely and cause an overheating scenario. I suggest checking the performance of the cooling fans and thermostat....

Q: No sound when the lock and panic key buttons are pressed.

After checking the wiring diagrams for the horn and antitheft system for your car I do not see where they connect in any way. I do not think the vehicle is equipped to sound the horn if you have the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...