HOUSING ASSEM. 4S5974 - Caterpillar

This engine has a pressure type cooling system that is equipped with a shunt line.A pressure type cooling system offers two advantages:
The cooling system can operate safely at a temperature that is higher than the normal boiling point of water.
The cooling system prevents cavitation in the water pump.Cavitation is the sudden formation of low-pressure bubbles in liquids by mechanical forces. The formation of air or steam pockets is more difficult within a pressure type cooling system.The shunt line prevents cavitation by the water pump. The shunt line provides a constant head pressure at the water pump inlet.Note: The coolant mixture must be a minimum of 30 percent ethylene glycol base antifreeze for efficient water pump performance for air to air after cooled engines. The mixture keeps the cavitation temperature range of the coolant high enough for efficient performance.
Illustration 1 g01155880
(1) Cylinder head
(2) Water temperature regulator housing
(3) Expansion tank
(4) Bypass hose
(5) Radiator
(6) Cylinder block
(7) Engine oil cooler
(8) Transmission oil cooler (if equipped)
(9) Water pumpWater pump (9) is located on the right side of the cylinder block. The water pump is gear-driven from the front gear group. Coolant can enter the water pump in two places:
Inlet at the bottom of the water pump
Bypass hose (4) at the top of the water pumpCoolant from the bottom of the radiator (5) is pulled into the bottom inlet of the water pump (9) by impeller rotation. The coolant exits the back of the pump directly into engine oil cooler (7). Some of the coolant is also diverted to transmission oil cooler (8) (if equipped).Some of the coolant passes through the core of engine oil cooler (7) and some of the coolant passes through the core of transmission oil cooler (8) (if equipped). The coolant then enters the internal water manifold of the cylinder block. The manifold disperses the coolant to water jackets around the cylinder walls.From the cylinder block, the coolant flows into passages in the cylinder heads. The passages send the flow around the unit injector sleeves and the inlet and the exhaust passages. The coolant now enters water temperature regulator housing (2) at the front of the cylinder head.
Illustration 2 g01206714
(2) Water temperature regulator housing
(4) Bypass hose
(9) Water pump
(10) Outlet to the radiator
(11) Inlet from the radiatorTwo