BELT-SERPENTINE 3718058 - Caterpillar

Illustration 1 g02022553
Coolant flow (jacket water)
(1) Pressure relief cap
(2) Top radiator hose
(3) Coolant inlet line
(4) Vent line
(5) Water temperature regulator
(6) Water cooled exhaust manifold
(7) Coolant outlet line
(8) Cylinder head
(9) Radiator
(10) Cylinder block
(11) Internal bypass
(12) Cylinder liner
(13) Bottom radiator hose
(14) Water pump
(15) Engine oil cooler
(16) Engine oil cooler bonnet Water pump (14) is located on the left front side of the engine. The water pump is gear-driven by the front gear train. Coolant from the bottom tank of radiator (9) is drawn through bottom radiator hose (13) by the water pump. The rotation of the impeller in the water pump pushes the coolant through the system.A portion of the coolant from the water pump goes through coolant inlet line (3) to water cooled exhaust manifold (6). The remainder of the coolant goes through engine oil cooler (15) to bonnet (16) on the outlet side of the engine oil cooler. Coolant flows through the bonnet into cylinder block (10).The coolant inlet line directs the coolant from the water pump to the front of the water cooled exhaust manifold. The coolant flows through the manifold to the rear of the engine. The coolant flows through coolant outlet line (7) into the oil cooler bonnet. The coolant is mixed with the remainder of the coolant.
Trapped air will cause hot spots in the water cooled exhaust manifold and in the cylinder head. Trapped air in the cooling system will cause high cooling system temperatures. Ensure that the vent line (4) is connected to the water cooled exhaust manifold and to some higher point in the cooling system. The vent line will prevent trapped air in the cooling system.
The coolant inside the cylinder block flows around cylinder liners (12). The coolant is pumped up through water directors into cylinder head (8). The coolant flows through passages around the valves and the combustion chambers that are in the cylinder head. The coolant flows into the front of the cylinder head to water temperature regulator (5). The water temperature regulator controls the volume and the direction of the coolant flow.If the coolant temperature is less than normal operating temperature, the water temperature regulator is closed. The only path that can be used by the coolant to exit the cylinder head is through internal bypass (11). The coolant from this line returns to the water pump. The water pump cycles the coolant through the system again. The flow of coolant through the bypass prevents cavitation by the coolant while the engine is warming up.When the coolant achieves normal operating temperature, the water temperature regulator opens and coolant flow is divided. The major portion of the coolant is sent to the radiator through top radiator hose (2). The remainder of the coolant goes through the internal bypass to the water pump.Note: The water temperature regulator is necessary to maintain the correct engine temperature. If the water temperature regulator is not installed in the system, control of the engine temperature is lost. The coolant will take the path of least