159255-5320 ZEXEL 9 421 620 710 BOSCH GOVERNOR COVER 9421620710 1592555320

Water Pump
Inspection of Water Pump
If the inspection of the impeller and shaft finds abnormal noise or rough rotation, replace the assembly.
Inspection of impeller and shaft rotation conditionThermostat
Disassembly of Thermostat
Inspection of Thermostat
To test the thermostat operation, immerse the thermostat in a container filled with water, and heat the water while measuring the water temperature. Record the temperature at which the valve starts to open and the temperature at which the valve lift becomes 8 mm [0.3 in.] or more. (a) Stir the water in the container to ensure uniform temperature distribution.(b) When installing the thermostat, be sure to check the valve opening temperature indication stamped on the upper face of the thermostat mounting flange.
Inspection of thermostatOverheat Warning Unit (Thermo Switch)
Inspection of Overheat Warning Unit
Immerse the temperature sensor in oil, and measure the resistance while increasing the oil temperature. If the temperature measurement exceeds the standard value significantly, replace the thermo switch.
Since the inspection requires heating of oil to high temperatures, be careful not to get burns or start a fire.
Overheat warning unit