Chevrolet 22538325 Thermostat Assembly, Engine Coolant

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The thermostat should be installed with the wax pellet facing downward.

The thermostat is a valve that regulates coolant flow in the engine. To remove it, disconnect the negative battery cable and remove the air cleaner. Drain the coolant and disconnect the upper radiator hose. Remove the thermostat housing bolts and the housing from the engine. Take note of the thermostat's position before removing it. Clean the gasket surfaces and apply sealer before installing the new thermostat. Reassemble the housing, reconnect the radiator hose, and refill the coolant. Start the engine and add more coolant if needed. Finally, install the radiator cap.

The only way to test the operation of the thermostat is with the unit removed from the engine. In most cases, if the thermostat is suspect, it is more economical to merely buy a replacement thermostat as they are not very costly. To test, first remove the thermostat. Inspect the thermostat for excessive corrosion or damage. Replace the thermostat with a new one if either of these conditions is found. Place the thermostat in hot water 25 degrees above the temperature stamped on the thermostat. Since nearly all Chevrolet V8 and V6 engines use a 195-degree thermostat, the water temperature will be approximately 220. When submerged in this water, which should be agitated thoroughly, the valve should be fully open. Now remove the thermostat using a piece of bent wire and place it in water which is 10 degrees below the temperature on the thermostat. In most cases, this cooler water temperature should be 185 degrees. At this temperature, the thermostat valve should close fully. Reinstall the thermostat if it checks out OK, or purchase a new thermostat of the same temperature rating for installing the thermostat.

To test the thermostat, first remove it. Inspect the thermostat for excessive corrosion or damage. Replace the thermostat with a new one if either of these conditions is found.

The thermostat is a restriction valve actuated by a thermostatic element, mounted inside a housing on the engine. It opens and closes at predetermined temperatures to regulate coolant flow for engine warm-up or cooling. To remove the thermostat, disconnect the negative battery cable and remove the air cleaner for better access. Drain the coolant into a suitable container. Disconnect the upper radiator hose from the thermostat housing and remove the housing bolts. Lift the housing to reveal the thermostat, noting its position for replacement. Clean the gasket surfaces on the housing and engine. Apply RTV or equivalent sealer and place the thermostat into its recess. Install the housing with a new gasket and tighten the bolts. If applicable, reinstall the alternator brace and TVS switch with vacuum hoses. Connect the upper radiator hose securely. Reconnect the negative battery cable and fill the radiator with the proper coolant mixture. Start the engine and add more coolant if needed. Finally, install the radiator cap, aligning the arrows with the overflow hose.

After lifting the thermostat housing from the engine, the thermostat will be visible and can be removed from the engine.

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