GM 10207373 Thermostat, Engine Coolant

Remove any gasket or sealer with the thermostat from the cylinder head. Unbolt the water neck by draining the coolant system below the thermostat level when trying to replace it. The next step is to remove the water neck and thereby expose the thermostat. Thereafter, clean off all traces of remnants from both manifold and residual gasket material or sealer on water necks that mate. Installing it with its wax pellet downwards is a good idea. Besides, apply some sealant on both sides of the gasket then put it on block. Finally, hold it down using retainer bolts.

Testing the thermostat in a far more convenient way can only be possible after it has been removed from the engine. In most cases, if one suspects a problem with the thermostat, then replacing it is less costly as they are not expensive. First remove the thermostat to test it. Check whether there is much rust or corrosion on the thermostat. If either of these conditions exists, install a new thermostat. Put the thermostat into water that's heated 25 degrees above its temperature marking. The water should be at around 220 degreesF (104 degreesC). When immersed in well-agitated water of this type, its valve will remain fully open. Then take out the latter by means of a wire bent and put again into water that is 10 degrees below its mark or about 185 degrees F (85 C). At this temperature, the thermostat valve ought to close completely. Replace it if it's good; otherwise buy another one with a similar temperature rating as before.

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

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

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

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.

If the thermostat checks out OK, it should be reinstalled.

The only way to test the operation of the thermostat is with the unit removed from the engine.

To remove the thermostat, you need to disconnect the negative battery cable, 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.

Begin by draining about three quarts of coolant from the radiator until the level is below the thermostat housing. Disconnect the upper radiator hose from the thermostat housing cover. Remove the nuts/bolts holding the cover and lift it off. It may be necessary to move the belt tensioner bracket aside and tap the cover with a soft-face hammer to break the gasket seal. Note the orientation of the old thermostat and then lift it out. Use a scraper or putty knife to remove any old gasket material and sealant from the mating surfaces, being careful not to let any fall into the coolant passages. Clean the mating surfaces with lacquer thinner or acetone. Apply a thin layer of ATV sealant to the gasket mating surfaces of the housing and cover. Install the new thermostat in the engine with the correct end facing up. Position a new gasket on the housing, ensuring the holes line up with the bolt holes. Carefully position the cover on the housing and install the bolts, tightening them to the specified torque without overtightening to avoid distortion. Reattach the radiator hose to the cover and tighten the clamp. It is recommended to check and replace hoses and clamps at this time. Refill the system with coolant. Run the engine and carefully check for any coolant leaks.

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.

Remove the thermostat from the housing.

Complete the installation process.