Valve opening temperature check
Pic. 2.393. Immersion thermostat in water
Immerse the thermostat in water and heat it up gradually (pic. 2.393).
Pic. 2.392. Marking indicating the opening temperature of the valve
Note. The valve opening temperature is indicated on the thermostat (pic. 2.392).
Check the opening temperature of the thermostat valve.
Valve opening temperature: 80–84°C.
If the valve opening temperature is not within specification, the thermostat must be replaced.
Valve Stroke Check
Valve travel: 10mm or more at 95°C.
Pic. 2.394. Valve Stroke Check
If the valve travel is not within specification, the thermostat should be replaced (pic. 2.394).
Make sure that at low thermostat temperature (below 77°C) valve is fully closed.
Otherwise, the thermostat must be replaced.
Radiator cap check
Note. If there is dirt or foreign matter on the radiator cap, wash it with water.
Note. Moisten the exhaust and intake valves with coolant or water before connecting the cooling system pressure tester and radiator cap tester.
Note. During the first two operations, the system crimping tool should be held at an angle of 30°or more to the horizontal.
Using a cooling system pressure tester and radiator cap check, slowly bleed air from the system and verify that air is being drawn in through the intake valve.
Pic. 2.395. Connecting the Crimping and Checking Tool for the Radiator Plug
Pumping frequency: 1 stroke in 3 s or more (pic. 2.395).
Note. Operate the pump at a constant speed.
Note. If air is not flowing through the intake valve, the radiator cap must be replaced.
While pumping air into the cooling system with the pressure tester pump, measure the opening pressure of the exhaust valve.
Pumping frequency: 1 stroke per second.
Note. The pump frequency above applies to the first compression only (to close the intake valve). After the first compression, the pumping frequency can be reduced.
- Nominal exhaust valve opening pressure: 74–103 kPa.
- Minimum allowable exhaust valve opening pressure: 59 kPa.
If the opening pressure of the exhaust valve is less than the minimum allowable value, the radiator cap should be replaced.
Note. The maximum value displayed on the pressure gauge on the pressure gauge is the opening pressure of the exhaust valve.