Thermostat Removal and Installation
1) Drain coolant referring to "Cooling System Draining".
2) Remove intake manifold referring to "Intake Manifold
Removal and Installation in Section 1D".
3) Disconnect water hose (1) and heater hose (2) from
4) Remove thermostat case (3) with thermostat cap (4)
and water inlet pipe (5).
5) Remove water inlet pipe with thermostat cap from
6) Remove thermostat from thermostat case (3).
Reverse removal procedure for installation noting the
• Install thermostat (5) to thermostat case (2) by
aligning air bleed valve (4) of thermostat with mark (3)
of thermostat case and, then install thermostat cap (1)
to thermostat case.
• Use new O-rings when installing.
• Refill cooling system referring to Step 7) to 17) of
"Cooling System Flush and Refill".
• Verify that there is no coolant leakage at each
Engine Cooling System:
• Make sure that air bleed valve (1) of thermostat is
• Check to make sure that valve seat (2) is free from
foreign matters which would prevent valve from
• Check thermostat seal (3) for breakage, deterioration
or any other damage.
• Check thermostatic movement of wax pellet as
a. Immerse thermostat (1) in water, and heat water
b. Check that valve starts to open at specific
Temperature at which valve begins to open
80 – 84 °C (176 – 183 °F)
Temperature at which valve become fully open
95 – 97 °C (203 – 206 °F)
More than 8 mm (0.31 in.) at 95 °C (203 °F)
If valve starts to open at a temperature substantially
below or above specific temperature, thermostat unit
should be replaced with a new one. Such a unit, if
reused, will bring about overcooling or overheating