About Engine Thermostats & Overheating

Engines need water and antifreeze to keep cool. Once the water circulates through the engine, it becomes hot. The vehicle's thermostat must recognize the temperature of the water, this way the water is kept cooled, so it does not overheat. Overheating an engine can cause significant damage.

Significance

An engine thermostat is an integral part of the engine. It keeps the antifreeze mixture at a balanced temperature. Without it, the
engine will run too hot, overheat and the car will not run. Damages such as warped or cracked heads or broken head gaskets occurs when the engine is significantly overheated or overheated many times.

Time Frame

An engine can overheat rapidly or slowly, depending on the problem. If a thermostat is stuck shut, the antifreeze will not flow, which means it's stuck in the engine and does not have a chance to return to the radiator for cooling. The engine will overheat rapidly, usually within 15 minutes or less. If the thermostat is stuck open, the water flows too fast, which can also cause overheating. Generally, because the water does pass through the radiator, cooling does happen, so it takes longer for the vehicle to overheat.

Features

Engine thermostats can be purchased for a variety of temperatures, but the optimum running temperature for most cars is 195 degrees Fahrenheit. The thermostat stays closed until the antifreeze comes up to temperature. Once it hits 205 degrees Fahrenheit, the thermostat opens and lets the antifreeze pass through the radiator, cooling it for another pass through the engine. When it opens, the water pump pumps the cool water from the radiator to the engine. This keeps the engine cool.

Identification

The engine thermostat is located in the thermostat housing on the top of the engine. The top radiator hose is attached to the
thermostat housing. The thermostat itself is a round piece of flat metal. On the top and bottom are brackets holding the actual mechanical parts of the thermostat in the middle of the round metal disc. As it senses temperature of the water passing through, it opens or closes as needed.

Considerations

When changing a radiator hose or the radiator, you should change the thermostat as preventative maintenance. Consider changing the thermostat at least every three years, especially if you plan on any long trips in that third year. It is not a requirement, but it could save you some heartache and money should the thermostat decide to lock up during the trip.