Removal and installation of the thermostat

OHC engines

Coolant pump and OHC engine thermostat

1. Disconnect ground wire from battery.

2. Drain the cooling system.



3. Disconnect the top hose from the thermostat housing at the front of the cylinder head.

4. Unscrew the bolts and remove the thermostat housing and gasket.


5. Pry off the spring clip with a screwdriver (drawing on the left) thermostat and remove the thermostat together with the O-ring (drawing on the right).


6. Clean mating surfaces of thermostat housing and cylinder head.



7. Installation is carried out in the reverse order of removal, while the arrow (shown by arrow) thermostat flow should be directed towards the engine.

8. Start and warm up the engine, and check the tightness of the cooling system connections.

9. After the engine has cooled down, check and, if necessary, top up the coolant level in the expansion tank.

DOHC engines

1. Disconnect ground wire from battery.

2. Drain the cooling system.

3. To improve access to the thermostat on engines with a fuel injection system, loosen the clamps and remove the tube connecting the pressure chamber and the intake manifold.



2. Drain the cooling system.


4. Disconnect the coolant hoses from the thermostat housing.



5. Disconnect the connector from the cooling fan switch located in the thermostat housing.



6. Unscrew the three bolts and remove the thermostat housing.



7. Installation is carried out in the reverse order of removal, while the safety valve of the thermostat must be installed upwards (shown by arrow).

V6 engines

The thermostat is removed during the removal of the water pump.