The thermostat is a small item that plays a large role in engine performance. Its primary function is to regulate the coolant that flows through the engine. When the engine is off and cold, the thermostat is closed. Once you crank the ignition on, the thermostat will open to regulate the coolant’s temperature so it can adequately recirculate. A functioning thermostat keeps the engine working at an optimum temperature.  Just like any other engine component, the thermostat can become worn or broken as well. If the thermostat is stuck closed due to a malfunction, the coolant won’t sufficiently circulate through the radiator and engine.

In comparison, if the thermostat is stuck open, the engine will not heat to a proper level. It’s essential to be aware of signs that the thermostat is due for a service to prevent significant engine damage that may lead to costly repairs. Below are five signs that your vehicle’s thermostat is failing.

The Engine is Overheating
 If the temperature gauge reports temperatures in the red for the first 15 minutes of the drive, the thermostat may be faulty. If the thermostat is worn, it can become stuck in the closed position. The coolant will not flow to the radiator, and the engine will overheat. 

The Engine is Too Cold.    
If the thermostat is stuck open, there will be too much coolant flowing through the radiator. If the engine fails to warm to an optimal temperature, it may be difficult to turn the vehicle on. It may choke and cause the combustion process to become incomplete. Additionally, If the thermostat won’t close, the heater will always malfunction. The result would be cold air flowing through the vents while the heater is turned on. 

Unusual Temperature Gauge Reading 
When you first turn on the ignition, the temperature gauge should display a cold reading. Once you’re on the road, the temperature should gradually increase. If the temperature gauge is stuck closed or open, the temperature reading displayed on the dashboard will be radically hotter or colder than usual. 

The Fuel Economy is Reduced. 
Whether a faulty temperature gauge causes the engine to run too hot or too cold, the vehicle must work harder to move. This additional stress on the engine can significantly decrease fuel efficiency. 

There’s a Coolant Leak.
If the thermostat is stuck in the closed positioning, the coolant can become backed up. Backed up coolant can overflow from the thermostat housing and start to leak. If this occurs, it’s essential to seek advice from an automotive expert to ensure there aren’t any significant problems. 

If you suspect your vehicle has a faulty thermostat, bring your vehicle into Longview Auto & Tire in Longview, WA. Our expert automotive technician will inspect your vehicle and identify the cause. 


More Posts


Knowing how to change a flat tire is a necessary skill for all drivers. These days we rely on our cell phones for many things.

Scroll to Top

Get Your Ebook Now

Per qualsiasi dubbio sentiti libera di contattarci, un membro del team di Eleiny ti risponderà al più presto!