You are watching: What does a thermostat do when it gets too hot
When running, the engine creates heat--lots the it. So much heat that it could start to melt itself. Part engines, such together those top top lawn mowers and some motorcycles, dissipate the excess warmth to the exterior air by way of fin on the cylinders.
Car engines usage water, combined with antifreeze/coolant, to eliminate excess heat. The coolant flows through holes and tunnels referred to as the water jacket of the engine. After it choose up heat, the coolant flows v the radiator, whereby the excess warmth is dissipated come the outside air.
Note that we say excess heat. Your car"s engine must keep a certain temperature, and also the thermostat regulates the price at i beg your pardon the coolant circulates v the engine. If the engine gets as well hot, the cylinder head could end up being distorted or the head gasket (between the cylinder head and also engine block) can blow. Overheating deserve to lead to other mechanical problems, too.
If the engine is as well cold, fuel effectiveness is poor and also emissions spike up. The onboard computer does not also trim the air/fuel ratio until it it s okay a signal indigenous the coolant temperature sensor that the engine has actually reached operation temperature. Engine undertake increases and heater calculation decreases as soon as the engine runs too cold.
The thermostat is a gatekeeper. That controls the flow.
Thermostats room rated top top the temperature at which they begin to open up and enable coolant to flow through. This opening temperature is typically 195 degrees Fahrenheit ~ above cars. Together the engine heats up, the thermostat opens much more to allow freer coolant flow. At around 20 degrees above its rated temperature, the thermostat is completely open.
It opens and closes slowly to maintain ideal engine temperature, which deserve to reach 250-275 degrees under some conditions. The thermostat is at least partially open at all times as soon as the engine warms up--even in sub-zero weather.
The thermostat is a an easy valve in i m sorry a spring-loaded plate prevents the coolant from flowing. A stick attached to the facility of that plate extends into a tiny chamber filled through wax. As the wax gets hot, it expands, putting press on the rod, i m sorry pushes on the plate. When the push overcomes the spring"s pressure, the thermostat starts to open. Together the expansion continues and also the pen pushes harder, the thermostat opens an ext and boosts coolant flow.
It is a an easy design that has actually not readjusted significantly in much more than 50 years. However it deserve to go bad.
If the thermostat falls short to open up or falls short to open up at the suitable temperature, her engine might overheat. The thermostat may stick shut if the wax pellet has actually been damaged by engine overheating from low coolant, clogged radiator or failed fan.
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The "stat may open too soon or never totally close if that is spring division or rubbish in the cooling device gets stuck in between the plate and housing.
Bob Weber is one ASE-certified Master automobile Technician, having recertified every five years since 1978. Call him at MMTribune