Examination
If there are defects in the cooling system, check the coolant level and the operation of the temperature gauge.
1. If the engine warms up very slowly after starting, the thermostat may be in a permanently open position and needs to be replaced.
2. If the engine overheats, check the temperature of the upper radiator hose by hand. If the hose is cold, then the thermostat may be in the closed position and not letting coolant through to the radiator. In this case, the thermostat must also be replaced.
3. If the thermostat is in the open position at room temperature, it must be replaced.
4. To test the thermostat, lower it with twine into a container of water. As the water gradually heats up, note the temperature at which the thermostat begins to open and opens fully. Take the thermostat out of the water and check that it closes completely after it cools down. Replace the thermostat if it is out of specification.
Replacement
Location of thermostat and water pump on 3VZ-FE V6 engines
1 - water supply pipe; 2 – O-ring; 3 - thermostat cover; 4 - sealing ring; 5 - thermostat; 6 - water pump
1. Remove the ground wire from the battery.
Attention! If your radio has an anti-theft code, check that you have the pairing codes before disconnecting the battery.
Attention! On models since 1993, the airbag system is disabled if the battery is disconnected for an extended period. If the airbag warning light comes on and stays on after reconnecting the battery, take it to a specialist workshop to restore the system to normal.
2. Drain the coolant from the radiator.
3. On four-cylinder engines, remove the water supply pipe to the engine from the radiator, which is located on the water pump housing. Remove the oil filter to gain access to the pipe mounting bolts.
4. On models with V6 engines, unscrew the bolt securing the water supply pipe and remove the pipe together with the O-ring (see fig. Location of thermostat and water pump on 3VZ-FE V6 engines).
5. Disconnect the electrical connectors from the thermostat housing and remove the thermostat housing from the engine. To improve access to the thermostat housing on the 1MZ-FE engine, remove the air filter housing and hoses.
6. Remove the thermostat, noting the position in which it was installed.
7. Install a new gasket on the thermostat.
8. Install the thermostat in the casing.
9. Install the thermostat housing to the cylinder block and secure with bolts.
10. Pour coolant into the engine cooling system.