Cooling System: Inspection

WARNING: This page is about a different car, the 2004 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT THERMOSTAT
HINT:

The thermostat is stamped with the valve opening temperature.

Fig 1: Inspecting 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: Checking Thermostat Valve
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Check the valve lift.
  Valve lift: 10 mm (0.39 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 temperatures (below 40°C (104°F)).
  If not closed, replace the thermostat.
  
  Fig 3: Checking Valve Is Fully Closed
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSPECT RADIATOR CAP SUB-ASSY
NOTE:
- If the reservoir cap has contaminations, 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) on the following page, keep the tester at an angle of over 30° above the horizontal.
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 coming from the vacuum valve, replace the reservoir cap.
2. Pump the tester and measure the relief valve opening pressure.
  
  Fig 4: Using A Radiator Cap Tester
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Pump speed: 1 push within 1 second
  
  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:
  
  93 to 123 kPa (0.95 to 1.25 kgf/cm ² , 13.5 to 17.8 psi)
  
  Minimum opening pressure:
  
  78 kPa (0.8 to 1.25 kgf/cm ² , 11.4 psi)
  
  HINT:
  
  Pay attention to the tester's maximum reading of the opening pressure. If the maximum reading is less than the minimum opening pressure above, replace the reservoir cap.