• Excel Autocare

What is a thermostat?

A thermostat is a small, yet important part of the vehicles cooling system. A thermostat is only present in liquid cooled cars. It sits between the engine and the radiator. Most thermostats are small, around 5 cm in diameter

What does your cars thermostat do?

The thermostat is designed to block the flow of coolant to the radiator until the engine is warmed up. When the engine is cold, no coolant flows through the engine until it reaches operating temperature, then the thermostat will open. This allows the engine to warm up as quickly as possible, reducing engine wear, deposits and emissions. To say it in more simple terms; when the thermostat is closed, coolant cannot flow into the radiator causing a rapid increase in engine temperature. Or when it is opened, coolant flows from the radiator where it dissipates hear and cools the hot coolant. Think of a thermostat as a gate valve which allows or blocks the flow of coolant from the engine to the radiator, all controlled by the temperature of the engine.

How does it work?

The thermostat contains a cylinder filled with wax. The cylinder lies on the engine side of the thermostat so that it stays in contact with the coolants that is circulating through the engine. Attached to the cylinder is a valve that connects to a rod; this rod presses into the wax at the center of the cylinder. When the engine temperature rises, this slowly melts the wax, which then expands, pushing the rod outwards. This motion is what opens the valve of the cylinder, allowing coolant to flow from the engine to the radiator

Ways to know you have a bad thermostat

The first and usually most alarming symptom the vehicle will have with a bad thermostat is the temperature will raise usually within the first 30 minutes of the engine running. While this is happening, the temperature will change erratically; it could hit as high as in the red or drop low suddenly. This can cause poor engine performance.

Another piece of evidence of a failing thermostat may be leaking coolant, cause by the thermostat not allowing coolant to flow when it is stuck in the closed position. One will commonly notice this around the thermostat housing, but areas such as coolant hoses in another possible area.

Replacing a cars thermostat is usually inexpensive repair, preventing potentially thousands of dollars in engine damage due to excessive heat. If you are having any of these symptoms, it may be time to give us a call to help your vehicle engine.

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