0282044 JOHNSON DECAL SET, 90

Illustration 1 g01956417
(1) Expansion tank (2) Jacket water to engine (3) Water pump (4) Jacket water from engine (5) Water temperature regulator housing (6) Engine (7) Aftercooler (8) Raw water inlet (9) Raw water outlet (10) Heat exchangerJacket Water System
The jacket water pump is located on the right front side of the engine. The water pump has a gear that is driven by the front gear group. Coolant from the radiator or from the heat exchanger enters the inlet. The rotation of the impeller in the jacket water pump pushes the coolant to the inlet of the engine oil cooler.The flow of coolant from the engine oil cooler is divided. Most of the coolant from the outlet of the engine oil cooler flows into the cylinder block.The remainder of the coolant flows through the tube in order to cool the turbocharger cartridge.The coolant inside the cylinder block flows around the cylinder liners. The water jacket is smaller near the top of the cylinder liners. This shelf causes the coolant to flow faster for better cooling of the cylinder liner. The coolant is pumped through the top deck of the cylinder block into the cylinder heads. The coolant flows through passages around the valves and around the exhaust gases in the cylinder head. The coolant then flows to the water temperature regulator housing. The water temperature regulator controls the direction of the coolant flow according to the coolant temperature.When the coolant is cold, the water temperature regulator is closed. The coolant is routed through the bypass tube to the jacket water pump. The coolant continues to circulate through the engine.When the coolant achieves normal operating temperature, the water temperature regulator opens and coolant flow is divided. Most of the coolant exits from the top of the water temperature regulator housing in order to be cooled by the radiator or by the heat exchanger. The remainder of the coolant flows through bypass tubes to the jacket water pump for recirculation. After the coolant is cooled by the radiator or by the heat exchanger, the coolant is routed to the inlet of the jacket water pump.Note: The water temperature regulator is necessary in order to maintain the correct engine temperature. If the water temperature regulator is not installed in the system, there is no mechanical control. Most of the coolant will take the path of least resistance through the bypass tube. This will cause the engine to overheat in hot weather. The small amount of coolant that goes through the radiator or through the heat exchanger in cold weather will not allow the engine to achieve normal operating temperatures. The water temperature regulators control the minimum temperature of the coolant. The radiator or the heat exchanger controls the maximum temperature of the coolant.The total system capacity depends on the amount of coolant in the cylinder block, the capacity of the piping, and of the radiator or heat exchanger.Separate Circuit
A separate cooling circuit is necessary for the aftercooler because the jacket water cannot provide the low coolant temperature that is necessary for cooling of the turbocharged air.The coolant flows through the passages in the aftercooler. The air that is compressed and heated by the turbocharger exchanges heat with the coolant in the aftercooler.The engine rating and the application determine the operating temperature of the aftercooler.