GM 10192505 Thermostat, Engine Coolant

The thermostat housing is on the upper end of both the 2.5L four-cylinder and 2.8L V6 engines. To remove, twist the thermostat housing cap clockwise, then pull out the thermostat. Clean the housing and lubricate the O-ring with white grease. If replacing the housing or gasket, disconnect the radiator hose (expect some coolant spillage). Disconnect the coolant temperature sensor wire. If replacing the housing, remove the sensor with caution. Remove old gasket residue from the cylinder head. Check the housing for external damage or internal corrosion. Apply RTV sealant to the new gasket and position it. Install the housing, tightening bolts securely. Wrap the sensor threads with Teflon tape, reattach it, and reconnect its wire. Refill with coolant, install the thermostat and its cap. Start the engine and check for leaks.

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 essentially a valve limiting the flow of coolant driven by a temperature sensitive element. It is placed in a housing on the engine, which opens and closes at fixed temperatures to the coolant warm up or cool down the engine. Disconnect the negative battery cable first to remove the thermostat for examination or replacement. Open the coolant drain valve located on the bottom right side of the radiator and allow coolant to drain into a suitable container. If your car has cruise control and has a 1981 or earlier L4 and all V6 models, take out the vacuum modulator mounting bracket on top of the thermostat housing. The bolts that hold down the water outlet are removed from their position at this point. The thermostat can now be seen and pulled off from its location on top of an engine block. At this point, we should note how it is positioned in its recess as it needs to go back exactly like that when replaced. Before installing it, there should be no traces of old gasket left on both sides of a cover plate and around an outlet pipe edge; therefore, one must apply some force with such tools as gasket scrapers or putty knives to clean these surfaces up without dropping any particles inside cooling system passages. A small bead of RTV or similar sealer should be applied around the sealing surface on the thermostat housing such that it goes into its recess and stays there after placing thermostats properly. Next, immediately position another new gasket together with water outlet over it before tightening screws/bolts until correct torque is reached. When appropriate reattach vacuum modulator bracket to thermostat housing; connect negative battery cable then fill radiator with proper mixture of antifreeze and water. After starting engine without cap on radiator until upper hose becomes hot; when it's hot enough; open it with pliers making sure that you won't damage rubber hoses nearby while twisting them counterclockwise till they're removed from its slot or pull them slightly to obtain better visibility then remove upper radiator hose clamp by squeezing it together until metal tabs are no longer inside it. At this point, more coolant may be injected if necessary so as to reach the filler neck's topmost level. The radiator cap is installed with arrows matched up with the overflow hose. Those L4 models that were manufactured from 1982 onwards have a redesigned thermostat/housing for ease of serviceability. Firstly, take off the thermostat housing cap in order to replace the thermostat. After this handle has been pulled out, the replacement is situated by replacing the thermostat into the housing and ensuring there is a seat before putting on the cap again.

Connect the negative battery cable and fill the radiator with the proper amount of antifreeze and water. Start the engine and run it until the upper radiator hose becomes hot, indicating that the thermostat is in the open position. Add more coolant if necessary to reach the top of the filler neck. Finally, install the radiator cap, aligning the arrows with the overflow hose.

First, remove the thermostat.

If the thermostat is suspect, it is more economical to merely buy a replacement thermostat as they are not very costly.

To remove the thermostat, start by disconnecting the negative battery cable. Then, open the coolant drain valve on the lower right side of the radiator and drain the coolant into a suitable container. Remove the necessary components such as the vacuum modulator mounting bracket and bolts securing the water outlet to the thermostat housing. The thermostat will then be visible and can be removed from the engine.

You can reinstall it.