When Good Thermostats Go Bad

The vehicles we drive these days are so high tech! But people are shocked when I tell them that their thermostat is operated by the heating and cooling of wax.

A thermostat sits between the engine and the radiator and blocks the flow of coolant to the radiator until the engine has warmed up. It essentially allows the car to warm while keeping the engine block cool. Once the engine reaches operating temperature, usually around 200 degrees F., the thermostat opens all the way.

It does this using wax!

It turns out that wax is remarkably reliable. The wax starts melting at 180 degrees (cylinder design can move this temp up or down). A rod connected to the valve presses into the wax, and when it melts, it expands, pushing the rod out of the cylinder and opening the valve, allowing the coolant to flow.

Since they rarely give us trouble, most people just don’t think about thermostats. But they do occasionally go bad, and when they do, look out! Your vehicle is going to overheat. Some reasons you might run into thermostat issues:

  • Prior overheating damage
  • Corrosion
  • Component wears out due to age

Burning the Thermostat at Both Ends

Sometimes the valve fails to close and gets stuck in the open position. This is a separate issue and can happen due to a piece of debris or when the return spring breaks. This allows coolant to keep flowing through the thermostat. Now, you have the opposite problem. The engine won’t reach the proper operating temperature. You might notice the temperature gauge reading lower than normal. Another symptom can be that the heater is no longer getting as hot as it used to. When the thermostat remains open, you’ll notice poor drivability during cooler weather. Fuel efficiency decreases by as much as 2 to 3 MPG. Your car will also spew out more pollutants.  

Upon Closer Inspection…

Our job is to keep your vehicle in excellent condition, such as spotting when a thermostat or other component is going out. We want to keep you as safe as possible on the highways and want to ensure the safety of those you share the road with. Most of you want to know that your car is in proper working order. Now and then, we hear stories about customers who think that an inspection, sometimes called a “laundry list,” was created for one reason—to make a bigger sale. This is not the case in most shops. Those that sell unneeded services don’t stay in business very long. You can trust businesses that are time-tested, especially one that has been around since 1978!

It’s critical to point out potential hazards. We are your experts in automotive maintenance. It’s our job to let you know when your vehicle needs work. We’ll help you prioritize can-do and can-wait items and work with you to navigate insurance and extended warranties.

You can count on Certified Automotive Specialists to treat you and your vehicle right!

We Are Open To Serve You.  Please Call 626.541.2149 For Service.

We Will Pick Up and Deliver Your Vehicle For Service At No Additional Charge Upon Request.