How to Change a Thermostat on a 1994 Toyota Truck

The thermostat on the engine of a 1994 Toyota pickup helps control the flow of coolant between the engine and the radiator. When the thermostat goes out, the coolant either stays stuck in the radiator or circulates continuously. Either way, the engine can potentially overheat in either of those situations. The best option is to replace the thermostat so that the engine functions correctly.

Instructions

1

Place the drain pan underneath the radiator. Open up the petcock on the bottom of the radiator, using your hands. Drain out approximately 2 qts. of coolant into the drain pan, then tighten the petcock.

2

Locate the upper radiator hose at the top of the radiator, and find where it connects to the engine. That is the thermostat housing. Unbolt the housing from the engine, using the 3/8-inch ratchet and socket, then pull the cover off the engine.

3

Pull the thermostat out of the engine and discard it. Remove the old gasket, using the gasket scraper. Set the replacement gasket onto the engine, then put the replacement thermostat into the engine, making sure it's the same orientation as the stock thermostat.

4

Place the thermostat housing back onto the engine and bolt it in place, using the 3/8-inch ratchet and socket. Open the radiator cap. Fill the radiator, using the 50-50 pre-diluted coolant. Reinstall the radiator cap.

5

Start the truck. Turn the heater on high and let the truck run for 15 minutes. Turn off the truck and allow it to sit for at least two hours. Open the radiator cap again and top off the radiator with the 50-50 pre-diluted coolant.