| WARNING | Do not remove radiator cap to check engine coolant level; check coolant visually at the see-through coolant reservoir. As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator without causing the solution to boil. Removal of the radiator cap while engine is hot and pressure is high will cause the solution to boil instantaneously and possibly with explosive force, spewing the solution over engine, fenders and person removing cap. If the solution contains flammable anti-freeze such as alcohol (not recommended for use at any time), there is also the possibility of causing a serious fire. Check to make sure that engine coolant temperature is cold before removing any part of cooling system. Also be sure to disconnect negative cable from battery terminal before removing any part. |
Cooling System Introduction
The cooling system consists of the radiator cap, coolant reservoir, hoses, water pump, cooling fan, and thermostat. The radiator is of tube-and-fin type.
Thermostat Description
- Temperature at which valve begins to open: 82 +/- 2°C (179 +/- 3.6 °F)
- Temperature at which valve becomes fully open: 95°C (203°F)
- Valve lift: More than 8 mm at 95°C (203°F)
Scheme 1
Cooling Fan Clutch Description
Fluid is enclosed in the cooling fan clutch and at its center front, there is a bimetal whose thermal reaction and the engine speed control the cooling fan speed.
The relation between the temperature detected by the fan clutch and operation of the fan clutch is as follows.
While the fan clutch detects a temperature lower than 50°C, it remains OFF and the fan revolution speed is constant (400 to 900 r/min. (rpm)) regardless of the engine speed. As the temperature reaches 50°C to 70°C, the fan clutch turns ON gradually and the fan revolution speed increases.
A temperature exceeding 70°C causes the fan clutch to turn ON and the fan revolution speed to increase in proportion with the engine speed.
Once the engine speed exceeds 4000 r/min. (rpm), however, the fan revolution speed becomes constant (2350 to 2650 r/min. (rpm)).
Note. Do not disassemble fan clutch.
Scheme 2
Coolant Description
The coolant recovery system is standard. The coolant in the radiator expands with heat, and the overflow is collected in the reservoir.
When the system cools down, the coolant is drawn back into the radiator.
The cooling system has been filled at the factory with a quality coolant that is a 50/50 mixture of water and ethylene glycol antifreeze.
This 50/50 mixture coolant solution provides freezing protection to -36°C (-33°F).
Scheme 3
Scheme 4
- Maintain cooling system freeze protection at -36°C (-33°F) to ensure protection against corrosion and loss of coolant from boiling. This should be done even if freezing temperatures are not expected.
- Add ethylene glycol base coolant when coolant has to be added because of coolant loss or to provide added protection against freezing at temperature lower than -36°C (-33°F).
Note. Alcohol or methanol base coolant or plain water alone should not be used in cooling system at any time as damage to cooling system could occur. Even in a market where no freezing temperature is anticipated, mixture of 70% water and 30% ethylene glycol antifreeze (Antifreeze / Anticorrosion coolant) should be used for the purpose of corrosion protection and lubrication. "Hard water", if used, will foul up the cooling circuit by scale formation. Tap water available from city water supply is the best available water, in a practical sense, for the cooling system. Distilled water is ideal but is a luxury in most cases.
Scheme 5
Scheme 6
- While the engine is warmed up (thermostat closed), coolant circulates as follows.
- When coolant is warmed up to normal temperature and the thermostat opens, coolant passes through the radiator core to be cooled as well as the above flow circuit.
