Toyota Tercel 1984-1994 Repair Guide




See Figures 1 and 2

The thermostat's purpose is to control the flow into the engine from the radiator. During warm up, the thermostat remains closed so that the coolant within the engine heats quickly and aids the warming up process.

As the coolant temperature increases, the thermostat gradually opens, allowing a supply of lower temperature coolant (from the radiator) to enter the water pump and circulate through the engine.

A thermostat should never be removed as a countermeasure to overheating problems. This will only decrease the cooling system efficiency and add to the problem. The vehicle cooling system should be serviced with necessary components replaced.

  1. Drain the cooling system and save the coolant for reuse.
  3. Remove the water inlet housing (disconnect any electrical connections on the housing) and remove the thermostat. Carefully observe the positioning of the thermostat within the housing before removal.
  5. Install the new thermostat in the housing, making sure it is in correctly. It is possible to install it backwards. Additionally, make certain that the air bleed valve aligns with the protrusion on the water inlet housing. Failure to observe this placement can result in poor air bleeding and possible overheating.
  7. Install the water inlet housing cover with a new gasket. Install the two hold-down bolts and torque to 43 inch lbs. (4.9 Nm). Do not overtighten these bolts!
  9. Refill the cooling system with coolant.
  11. Start the engine. During the warm up period, observe the temperature gauge for normal behavior. Also during this period, check the water inlet housing area for any sign of leakage. Remember to check for leaks under both cold and hot conditions.

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Fig. Fig. 1: Always observe the positioning of the thermostat in the housing before removing it

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Fig. Fig. 2: The thermostat should be installed with the jiggle valve upwards