Thermostat: Testing and Inspection

Inspection





^ Make sure that air bleed valve (1) of thermostat is clean.
Should this valve be clogged, engine would tend to overheat.
^ Check to make sure that valve seat is free from foreign matters which would prevent valve from seating tight.
^ Check thermostat seal (2) for breakage, deterioration or any other damage.
^ Check thermostatic movement of wax pellet as follows:
- Immerse thermostat (1) in water, and heat water gradually.
- Check that valve starts to open at specific temperature.
Temperature at which valve begins to open 80 - 84°C (176 - 183°F)
Temperature at which valve become fully open 95 - 97°C (203°F)
Valve lift More than 8 mm at 95°C (203°F)





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.