How does the thermostat in a car’s cooling system work?

How does the thermostat in a car’s cooling system work?

Close up of a car's temperature gauge.


A thermostat reduces engine wear, deposits, and emissions by letting the engine warm up quickly. Jhà nội car
ckyenjoyphotography / Getty Images

­Any liquid-cooled car engine has a small device called the thermostat that sits between the engine and the radiator. The thermostat in most cars is about 2 inches (5 cm) in diameter. Its job is to block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the engine. Once the engine reaches its operating temperature (generally about 200 degrees F, 95 degrees C), the thermostat opens. By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions.

If you ever have the chance béo demo one, a thermostat is an amazing thing mập watch because what they vì seems impossible. You can put one in a pot of boiling water on the stove. As it heats up, its valve opens about an inc, apparently by magic ! If you’d lượt thích phệ try this yourself, go phệ a car parts store & buy one for a couple of bucks .

The secret of the thermostat lies in the small cylinder located on the engine-side of the device. This cylinder is filled with a wax that begins to melt at perhaps 180 degrees F (different thermostats open at different temperatures, but 180 F/82 C is a common temperature). A rod connected to the valve presses into this wax. When the wax melts, it expands significantly and pushes the rod out of the cylinder, opening the valve. If you have read How Thermometers Work and done the experiment with the bottle and the straw, you have seen the same process in action. The wax happens to expand a good bit more because it is changing from a solid to a liquid in addition to expanding from the heat.

This same technique is used in automatic openers for greenhouse vents và skylights. See this page for an example. In these devices, the wax melts at a lower temperature .

Thes e link will help you learn more :

  • How Car Cooling Systems Work
  • How Home Thermostats Work
  • How Thermometers Work
  • How the Eden Project Works
  • GM Goodwrench Videos

Advertisement Originally Published : Apr 1, 2.000

Car Thermostat FAQs

What are the telltale signs of a failing thermostat?

Signs include very high temperature readings, an overheating engine, leaking coolant và erratic changes in temperature .

What should I expect to pay to replace my car thermostat?

On average, a professional mechanic will charge you USD 140 – $ 300. It’s safe lớn assume that this estimate will vary from car lớn car .

What will happen if I drive my car without a thermostat?

A car without a thermostat will not let the engine reach optimal operating temperature. It may also result in the heater giving off cold air .
​Cite This !
Please copy / paste the following text Khủng properly cite this HowStuffWorks. com article :

“How does the thermostat in a car’s cooling system work?”
1 April 2000.
29 April 2023

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