Thermostat: Service and Repair

Removal
1. Drain coolant and tighten drain plug.
2. Remove fan shroud with cooling fan after disconnecting radiator inlet hose from radiator.





3. Remove thermostat cap (1).
4. Remove thermostat.

Installation





1. When positioning thermostat (1) and O-ring on thermostat case, be sure to position it so that air bleed valve (2) comes at match mark (3) and into the recession of thermostat case.
2. Install thermostat cap to thermostat case.
3. Install cooling fan and fan shroud and connect radiator inlet hose to radiator.
4. Fill cooling system.
5. Connect negative cable at battery.
6. After installation, check each part for leakage.

Inspection
1. Make sure that air bleed valve (1) of thermostat is clean. Should this valve be clogged, engine would tend to overheat.
2. Check to make sure that valve seat is free from foreign matters which would prevent valve from seating tight.





3. Check thermostat seal (2) and O-ring for breakage, deterioration or any other damage.





4. Check thermostatic movement of wax pellet as follows:
a. Immerse thermostat (1) in water, and heat water gradually.
b. Check that valve starts to open at specific temperature.
c. If valve starts to open at a temperature substantially below or above specific temperature, thermostat unit should be replaced with a new one. Such a unit, if reused, will bring about over cooling or overheating tendency.