Heating, Cooling Problems May Signal Aging Thermostat

You topped off the oil and coolant before heading out on the family vacation. Now you're driving up a steep mountain road and suddenly the temperature gauge is climbing, too.

What could be wrong?

“The problem could be your vehicle’s thermostat,” said Tony Molla, vice president of the Automotive Service Association, a trade group for repair shops and service centers. “Thermostats can wear out and when they fail, they can cause your engine to quickly overheat, especially in hot weather.”

A vehicle’s thermostat is a soup can-sized part that could cause big headaches. Located near the cooling system, a thermostat contains a wax-like substance that turns to liquid when your  vehicle heats up. 

The process opens and closes a valve which controls coolant to into the engine compartment. Unfortunately, a worn thermostat can get stuck in either the open or closed position.

“Thermostats have a lifespan and they often fail in the half-open position,” Molla said. “That means your engine is not getting the cooling it needs during summer and it also prevents your vehicle from warming up quickly on those cold winter nights.”

The only way to know for sure if your thermostat has failed is to remove it. Yet, Molla had the following suggestions for people who are planning a road trip:

• Look for signs your thermostat may be acting up. Does your car overheat in summer or take long time to warm up in winter?
• Inspect hoses, fittings and gaskets for leaks. For instance, the seal that surrounding the thermostat may be corroded. Ask your service advisor to inspect any leaks before they can cause engine damage.
• Make sure the coolant reservoir is full and engine oil is above the minimum level recommended.
• Find out if your car is due for a coolant flush. Like oil, coolant breaks down and loses its ability to cool your vehicle’s engine. 
• Replace the thermostat anytime you have your cooling system flushed. Thermostats are inexpensive to replace but can cause major damage when they go bad.
• Check the cooling system annually, especially if you are going on vacation.

“Ask your service advisor about getting your thermostat replaced when the cooling system is flushed,” Molla said. “A thermostat is an inexpensive part that can cause expensive damage if it goes bad.”