GM 10207373 Thermostat, Engine Coolant

A thermostatic element inside a housing on the engine actuates the thermostat, which is a restriction valve. It opens and closes to regulate coolant flow at predetermined temperatures, thereby enabling either engine warm-up or cooling. Disconnect the negative battery cable and remove the air cleaner so you can get at the thermostat with ease. Find a suitable container and drain the coolant into it. Remove the thermostat housing bolts and disconnect upper radiator hose from it. At this point, lift up the housing hence exposing the thermostat while considering where it was located previously for later replacement. Clean both surfaces of gaskets on housing and engine body. Insert RTV or equivalent sealer and put the thermostat onto its space properly. With new gasket, fit housing on with correct tightening of bolts. If necessary, re-attach alternator brace and TVS switch plus vacuum hoses as well. Make sure that upper radiator hose is securely attached. Reconnect negative battery cable then use right coolant mixture to fill radiator. Start engine; if necessary pour more coolant into system hereafter. Finally put back radiator cap matching arrows on it with overflow hose.

The gasket should be secured in place using the retainer bolts.

After removing the water neck, the thermostat can be lifted out.

The thermostat is designed to open and close at predetermined temperatures to allow coolant to warm up or cool the engine.

If the engine takes a long time to warm up, it is likely that the thermostat is stuck open and should be replaced.

The cooler water used for testing should be 10 degrees below the temperature on the thermostat. In most cases, this cooler water temperature should be 185 degrees.

Begin by draining about three quarts of coolant from the radiator until the level is below the thermostat housing.

Before removing the thermostat, it is important to take note of its position.

When submerged in the hot water, which should be agitated thoroughly, the valve of the thermostat should be fully open.

Check the coolant level in the system. Verify the drivebelt tension is correct. Observe the temperature gauge or light operation. If the engine takes a long time to warm up, it may indicate a thermostat stuck open and needs replacement. If the engine runs hot, and the upper radiator hose isn't hot, it suggests a thermostat stuck shut and should be replaced. If the upper radiator hose is hot, it indicates that the coolant is circulating and the thermostat is open.

Remove the thermostat from the housing.

Drain the cooling system below the thermostat level and disconnect the upper radiator hose from the thermostat housing.

If there is a TVS switch installed in the thermostat housing, disconnect each of the vacuum hoses on the switch and then unscrew the switch from the housing.

If the thermostat fails the tests, a new thermostat of the same temperature rating should be purchased for installation.