The thermostat is located in the water inlet housing that is connected to the lower radiator hose.
The thermostat is equipped with a by-pass valve. If the engine tends to overheat, removal of the thermostat would cause a decrease in cooling system efficiency.
- Position a suitable drain pan under the radiator drain cock and drain the cooling system.
- On the 7A-FE engine disconnect the engine coolant temperature switch harness from the water inlet housing.
- Remove the oil filter on 5S-FE engines.
- Loosen the hose clamp and disconnect the lower radiator hose from the water inlet housing.
- Remove the two nuts from the water inlet housing and remove the housing from the water pump studs.
- Remove the thermostat and rubber O-ring gasket from the water inlet housing.
- Make sure all the gasket surfaces are clean. Clean the inside of the inlet housing and the radiator hose connection with a rag.
- Install the new rubber O-ring gasket onto the thermostat. On 5S-FE engines, align the jiggle valve with the upper side of the stud bolt. Insert the thermostat into the housing.
- Position the water inlet housing with the thermostat over the studs on the water pump and install the two nuts. Tighten the two nuts to 78-82 inch lbs. (9-10 Nm).
Don't forget to install a new O-ring onto the water inlet pipe. Apply soapy water to the O-ring prior to installation.
- Connect the lower radiator hose to the inlet housing and install the hose clamp.
- Attach the water temperature switch connector.
- Install the oil filter and check the oil level if removed.
- Fill the cooling system with a good brand of ethylene glycol based coolant.
- Start the engine and inspect for leaks.
- Remove the right hand cover under the engine.
- Drain the engine coolant.
- Remove the fan and generator V belt.
- Remove the generator assembly
- Remove the water inlet via the two nuts.
- Remove the thermostat.
- Install a new gasket onto the thermostat.
- Install the thermostat with the jiggle valve upward. It can be set within 10 degrees on either side of the prescribed position.
- Install the water inlet via the two nuts. Torque to 8 ft. lbs. (11 Nm).
- Install the generator assembly.
- Add engine coolant.
- Inspect for leaks.
- Replace the cover under the engine.