Cooling System; Cooling Water And Radiator - Mitsubishi 4DQ50 Service Manual

5 COOLING SYSTEM
Thermostat
Thermogauge
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- Engine water
Radiator
jacket
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---::-, Dral'n cock
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Oil
cool:7-~Drain
cock
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Fig. 3-35 Cooling system diagram
As illustrated in the diagram (Fig. 3-35). cooling water is kept in forced circulation by
centrifugal water pump. The system has a thermostat, whose valve remains close at low
water temperature, letting cooling water circulate between water pump and engine body via
bypass hose, and opens, as water gets hot from absorbing heat from crankcase, cylinder
head, etc., to let it run into radiator to
be
cooled there by air blasts from fan, and at the
same time, close bypass hose.
Thermostat case on cylinder head has two bosses: one covering hole to fit in thermostat
and the other, water outlet for car heater.
5-1 Cooling water and radiator
1) For checkup of water level, refer to "Checkup and preparations prior to
starting".
2) In order to remove scale and dust in radiator and engine water jacket to
improve cooling efficiency, open drain cocks to drain, fill radiator with fresh
oil through its inlet, and run the engine for some 20 minutes for flushing, at
intervals of 500Hr or 12,OOOkm of run, or twice a year (in spring and fall).
If they have gathered much scale and dust, run the engine for about 30 minutes
with caustic soda solution or cleansing liquid in the system and drain it off
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