Cooling System - Suzuki K6A-YH6 Technical/Repair Manual

4.3 Cooling System

See Figure 4-3.
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The cooling system includes the radiator (4), water pump
(5), thermostat (7), and engine coolant passages.
Coolant is circulated from the water pump (5) into the
engine coolant passages and circulates around the
cylinders. From the cylinders, coolant flows up through
the block deck passages and into the cylinder head (2).
In the cylinder head (2), the coolant flows through
passages around the intake and exhaust ports, valve
seats, and combustion chambers. Coolant flows toward
the rear of the cylinder head (2) and exits through the
thermostat housing (8).
During the warm-up period, the thermostat (7) is closed
and coolant flows only through the jiggle pin (1) opening
to provide a fast warm-up period. The jiggle pin (1) also
helps ensure that no air is trapped in the engine when
filling the cooling system.
Once the engine has reached operating temperature, the
thermostat (7) opens and allows coolant to flow through
the upper radiator hose to the radiator (4) top tank.
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1 Jiggle Pin
2 Cylinder Head
3 Overflow Bottle
4 Radiator
Figure 4-3
THEORY OF OPERATION
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5 Water Pump
6 Cylinder Block
7 Thermostat
8 Thermostat Housing
Coolant circulates through the radiator (4), dissipates
heat, and then flows out of the radiator (4) through the
lower hose and into the suction side of the water pump
(5).
If coolant temperature begins to become excessive, the
radiator pressure cap will open and allow excess coolant
to flow into the overflow bottle (3). When coolant
temperature lowers enough, the radiator cap will close.
As the coolant continues to cool, a vacuum will be
created in the radiator (4). This will open a valve in the
radiator cap that will syphon the excess coolant from the
overflow bottle (3) back into the radiator (4).
Coolant continues flowing through the engine and
radiator circuit until the coolant temperature drops below
the thermostat (7) opening temperature. The thermostat
(7) will remain open until coolant temperature falls below
the thermostat closing temperature. At that time the
thermostat (7) will close and begin a new cycle of
warming the coolant.
This repeated cycle of temperature control keeps the
engine at the optimal temperature for clean and efficient
performance.
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