How to Remove a Thermostat From an Engine

Most modern internal combustion engines have a thermostat in the cooling system that helps the engine warm up quickly during cold weather. The thermostat remains closed, blocking coolant flow until the engine reaches a preset temperature. But with age a thermostat can fail to open and cause your engine to overheat. Fortunately, replacing a thermostat is a relatively simple process.

Instructions

1

Drain the engine coolant. Most radiators have a petcock valve at the bottom. Simply place a bucket under the radiator and loosen the petcock to allow the fluid to flow out. You may need to use a pair of pliers to get enough leverage to loosen the petcock. Alternatively, you can loosen the lower radiator hose to drain the radiator.

2

Locate the thermostat housing. Follow the upper radiator hose to where it attaches to the engine. This is the thermostat housing, which is usually attached to the engine with two bolts. The radiator hose slips over the housing and is attached with a large hose clamp.

3

Remove the two bolts holding the housing to the engine with a ratchet wrench and lift it off the housing. Note the orientation of the thermostat inside before removing it.

4

Scrape any old gasket material off of the thermostat housing and the engine surface, being careful not to nick either surface to avoid potential leaks.