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G643 (E) Service Manual Chapter 3. Engine Mechanical System
51
Cooling System
General Description
Cooling System Schematic
(1) Cylinder head. (2) Thermostat. (3) Recovery tank. (5) Radiator top hose. (6) Radiator pressure cap.
(7) Cylinder walls. (8) Radiator. (9) Radiator lower hose. (10) Water pump.
Water pump (10) is installed on the front of the
cylinder block. The water pump is driven by a single
V belt from the crankshaft pulley. The inlet opening
of the water pump is connected to the radiator lower
hose (9). The outlet flow from the water pump goes
through passages inside the cylinder block.
The coolant from the water pump through the
cylinder block passages has primary coolant flow to
and around the seats for the exhaust valves. This
method gives the coolant with the coolest
temperature flow to the hottest area during engine
operation.
Cylinder walls (7) are cooled by the coolant flow
through the block. After the coolant goes through the
cylinder block it flows through cylinder head (1) to
the thermostat housing, where the bypass type
thermostat (2) is installed. The thermostat controls
the opening to radiator (8) to control the temperature
in the cooling system.
If the coolant is cold (cool), the thermostat will be
closed. The coolant circulates (makes a complete
circuit) from the water pump and through the
cylinder block until the temperature of the coolant is
warm enough to make the thermostat open. When
thermostat (2) is open the coolant will go through
radiator top hose (5) and into the top tank of radiator
(8). Coolant then goes through the cores of the
radiator. The air from the fan will make the coolant
cool as the coolant flows to the bottom of the
radiator and out hose (9) where the coolant returns
to water pump (10).
The radiator is equipped with a shroud to increase
the efficiency of the fan and cause the air to be
pushed through the radiator and away from the lift
truck.
If the coolant is hot and the cooling system pressure
is too high, some coolant flows to the top of radiator
(8) through the tube to recovery tank (3). The
cooling system pressure is controlled by cap (6).
When the cooling system pressure goes above its
rated pressure, a valve opens in pressure cap (6)
which releases the cooling system pressure to the
atmosphere. After the engine is at normal
temperature for operation, a development of vacuum
is present in the cooling system. Pressure cap (6)
permits air in the radiator to remove the vacuum at
the same time coolant from recovery tank (3) is
pulled back into the radiator.
Содержание G643
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Страница 43: ...G643 E Service Manual Chapter 3 Engine Mechanical System 41 Engine Exploded View...
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Страница 132: ...G643 E Service Manual Chapter 4 Engine Electrical System 130 2 Alternator and outer terminal connection inspection...
Страница 181: ...G643 E Service Manual Chapter 5 Engine Management System EMS 179 SECM Wiring Diagrams for G643 LP Engine...
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