Section 129 (Engine Cooling System): Inspection

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

INSPECT THERMOSTAT

HINT:

The thermostat is imprinted with the valve opening temperature.

Fig 1: Checking Thermostat Valve Opening Temperature

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Immerse the thermostat in the water, then gradually heat the water.
Check the valve opening temperature.
1. Valve opening temperature:
2. 80 to 84°C (176 to 183°F)
HINT:

If the valve opening temperature is not as specified, replace the thermostat.

Fig 2: Checking Valve Opening Temperature In Hot Water
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the valve lift.

Valve lift:

TEMPERATURE VALVE LIFT

Temperature	Valve Lift
95°C (205°F)	8.5 mm (0.335 in.) or more

If the valve lift is not as specified, replace the thermostat.

Check that the valve is fully closed when the thermostat is at low temperature (below 77°C (171 °F)).

If not fully closed, replace the thermostat.

Fig 3: Checking Valve Lift

INSPECT RADIATOR CAP SUB-ASSY
NOTE:
- If the water filler cap is dirty, clean it with water.
- Before using the radiator cap tester, wet the relief valve and pressure valve with coolant or water.
1. Using a radiator cap tester, slowly pump the tester and check that the air is coming form the vacuum valve.
  1. Pumping speed: 1 push / 3 seconds or more
  NOTE:
  - Pump the tester at a constant speed.
  - Slant the radiator cap tester at an angle of over 30° as shown in the illustration when checking.
  If air is not coming from the vacuum valve, replace the radiator cap.
  
  Fig 4: Checking Radiator Cap With Radiator Cap Tester
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Pump the tester, then measure the relief valve opening pressure.
  1. Pumping speed: 1 push /1 second or more
NOTE:
- This pumping speed is for only the first pumping to close the vacuum valve. After the first pumping, the pumping speed can be reduced.
- Slant the radiator cap tester at an angle of over 30° as shown in the illustration when checking.
  Standard opening pressure:74 to 103 kPa (0.75 to 1.05 kgf/cm² , 10.7 to 14.9 psi)
  
  Minimum opening pressure:59 kPa (0.6 kgf/cm2, 8.5 psi)
HINT:

Use the tester's maximum reading as the opening pressure.

If the opening pressure is less than minimum, replace the radiator cap.