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Chapter 6 Cooling System Inspection
(MR7131A, MR7151A, MR7161A)
Section 1 System Check
1. Check the cooling system for leakage. See (Figure 118)
(a) Fill coolant into radiator. Install the tester onto the radiator cap port.
(b) Start engine.
(c) The water pump pressure is 118Kpa. Check the pressure and ensure the
pressure will not drop. If the pressure drops, check the port, radiator and
water pump for leakage. If there is no leakage, check the heat exchanger,
cylinder block and cylinder head.
2. Check the engine coolant level in the reservoir.
The coolant level should be between low and full marks.
3. Check coolant quality
(a) Remove radiator cap.
To avoid being scalded, do not remove radiator cap while the engine and
radiator are still hot, as fluid and steam can be sprayed under pressure.
(b) There should not be excessive deposits of rust or scale around the radiator,
and the coolant should be free from oil.
(c) Reinstall the radiator cap.
4. Thermostat
Hint:
The thermostat temp indicates the valve opening temperature.
See (Figure 119).
(a) Immerse the thermostat in water and gradually heat the water.
(b) Check the valve opening temperature. Valve opening temperature: 80 -- 84°C
(c) Check the valve lift. See (Figure 120, Figure 121). Valve lift: 8mm or mor at
95°C
(d) Check the thermostat is fully closed when the thermostat is at low temperature
( 77°C).
5. Radiator cap valve
Standard opening pressure: 93-123kpa
Minimum opening pressure: 78kpa
If the opening pressure is less thanminimum, replace the radiator cap.
Figure 118
Figure 119
Figure 120
Figure 121
Radiator Cap Tester
8.0mm or
More
≤
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