COVER 2Y5741 - Caterpillar

Illustration 1 g01932599
Cooling system schematic
(1) Cylinder head
(2) NRS Cooler
(3) Water temperature regulator housing
(4) Expansion tank
(5) Shunt line (expansion tank to water pump)
(6) Bypass
(7) Radiator
(8) Cylinder block
(9) Oil cooler
(10) Water pump Water pump (10) is located on the right side of the cylinder block. The water pump is belt driven from the crankshaft pulley. Coolant can enter the water pump in three places:
Inlet at the bottom of the water pump
Bypass (6) into the top of the water pump
Shunt line (5) into the top of the water pumpCoolant from the bottom of the radiator is pulled into the bottom inlet of the pump by impeller rotation. The coolant exits the back of the pump directly into the oil cooler cavity of the block.All of the coolant passes through the core of the oil cooler and the coolant enters the internal water manifold of the cylinder block. The manifold disperses the coolant to water jackets around the cylinder walls.The coolant flows from the cylinder block into the NRS cooler. The coolant flows from the NRS cooler back to the cylinder block.From the cylinder block, the coolant flows into passages in the cylinder head. 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 (3) at the front right side.The water temperature regulator controls the direction of flow. When the coolant temperature is below the normal operating temperature, the water temperature regulator is closed. The coolant is directed through bypass (6) and into the top inlet of the water pump. When the coolant temperature reaches the normal operating temperature, the water temperature regulator opens. When the water temperature regulator is open, the bypass is closed. Most of the coolant goes through the outlet to the radiator for cooling. The remainder flows through bypass (6) and into the water pump.The shunt line (5) extends from the top of the water pump to an expansion tank. The shunt line must be routed properly in order to avoid trapping any air. By providing a constant head pressure to the water pump, the shunt line can provide a constant flow of coolant to the water pump. This shunt line prevents cavitation by the water pump.Note: The water temperature regulator is an important part of the cooling system. The water temperature regulator divides coolant flow between the radiator and the bypass in order to maintain the normal operating temperature. If the water temperature regulator is not installed, there is no mechanical control, and most of the coolant will travel the path of least resistance. The path of least resistance is through the bypass. Also, the lack of control will cause the engine to overheat in hot weather and not reach normal operating temperature in cold weather.Coolant For Air Compressor (If Equipped)
If the engine is equipped with an air compressor, the air compressor coolant is supplied from the water temperature regulator housing through the supply line. The coolant is circulated through the air compressor