Thermostat: Service and Repair

THERMOSTAT REMOVAL
1. Drain coolant and tighten drain plug.
2. Remove radiator outlet hose at thermostat cap.





3. Remove thermostat cap.





4. Remove thermostat.

INSPECTION





1. Make sure that air bleed valve 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 for breakage, deterioration or any other damage.





4. Check thermostatic movement of wax pellet as follows:
i. Immerse thermostat in water, and heat water gradually.
ii. Check that valve starts to open at specific temperature.
iii. 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 overcooling or overheating tendency.

INSTALLATION





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