Engine Cooling System: Inspection

INSPECT THERMOSTAT
HINT:

The thermostat is numbered with the valve opening temperature.

Fig 1: Identifying Valve Opening Temperature On Thermostat
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Immerse the thermostat in water and gradually heat the water.
2. Check the valve opening temperature.
  Valve opening temperature: 80 to 84°C (176 to 183°F)
  
  If the valve opening temperature is not as specified, replace the thermostat.
  
  Fig 2: Immersing Thermostat In Water & Heating Water
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Check the valve lift.
  Valve lift: 7.7 mm (0.3031 in.) or more at 95°C (203°F)
  
  If the valve lift is not as specified, replace the thermostat.
4. Check that the valve is fully closed when the thermostat is at low temperature (below 40°C (104°F)).
  If not closed, replace the thermostat.
INSPECT RADIATOR CAP SUB-ASSY
NOTE:
- If the reservoir cap is contaminated, always rinse it with water.
- Before using a radiator cap tester, wet the relief valve and pressure valve with engine coolant or water.
- When performing steps a and b below, keep the tester at an angle of over 30° above the horizontal.
Fig 3: Checking Valve Lift
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Using a radiator cap tester, slowly pump the tester and check that air is being released from the vacuum valve.
  Pump speed: 1 push every 3 seconds or more
  
  NOTE: Push the pump at a constant speed.
  
  If air is not being released from the vacuum valve, replace the reservoir cap.
2. Pump the tester and measure the relief valve opening pressure
  Pump speed: 1 push within 1 second
  
  Fig 4: Checking Air Is Being Released From Vacuum Valve
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  NOTE: The pump speed above should be followed for the first pump only. It will close the vacuum valve. Once the vacuum valve is closed, the pump speed can be reduced.
  
  Standard opening pressure:
  
  69.0 to 112.8 kPa (0.70 to 1.15 kgf/cm ² , 10.0 to 16.4 psi)
  
  HINT:
  
  Use the tester's maximum reading as the opening pressure. If the maximum reading is less than the minimum opening pressure above, replace the radiator cap.