How to Locate a Car Thermostat

Learning how to locate a car thermostat is an important first step in replacing this vital part of your car's engine cooling system. The thermostat regulates the flow of coolant through your car's engine based on the internal temperature of the engine itself.

Locate A Car Thermostat Quickly

When your engine starts, the thermostat actually blocks the flow of coolant into the engine. This temporary blockage allows the engine to quickly warm to its operating temperature. By warming the engine quickly, the thermostat helps increase fuel efficiency and reduce emissions. Once the engine is warmed, the thermostat lets coolant flow to prevent the engine from overheating. But what if your thermostat malfunctions? The first step in this simple repair is to locate the car thermostat. Here's where to find it:

• The cooling system. The water pump is the heart of your car's cooling system-it circulates coolant through channels in the engine block called cooling jackets. As heated coolant leaves the engine through hoses, it passes through the radiator, which uses cool air to lower the temperature of the coolant. Once the coolant returns to operating temperature it leaves the radiator through a hose, passes through the thermostat and back into the engine.
• "X" marks the spot. Most cars have the thermostat located at the end of the top radiator hose where it enters the engine. If the thermostat is located off the bottom of the radiator, it will be much harder to locate and replace. The owner's or repair manual for your vehicle can give you a more accurate location for the thermostat.
• What to look for. The end of the radiator hose should be clamped to a metal housing. This housing may be spherical or cylindrical, but it will usually be bolted directly to the engine block. The thermostat sits under this housing-look for a disk shaped metal part with a good-sized spring attached. The thermostat will often have a three-digit number (its temperature rating) stamped on its side.