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| Illustration 1 | g02422336 |
Cooling system (1) Power train oil cooler (2) Water regulator (3) Bypass (4) Radiator (5) Engine oil cooler (6) Water pump (AA) Regulated coolant (BB) Unrestricted coolant | |
Water pump (6) draws coolant directly from the radiator (4). Coolant is pumped through engine oil cooler (5) and transmission oil cooler (1). Then, the coolant flows into the engine block. Coolant flows around the cylinder liners, through the water directors and into the cylinder head. The water directors send the flow of coolant around the valves and the passages for exhaust gases in the cylinder head. The coolant then goes to the front of the cylinder head and into water regulator housing (2). When the coolant is inside the housing, the water regulator controls the direction of coolant flow within the housing.
When the coolant temperature is below 81 °C (178 °F), the water regulator will be closed. The path for the coolant return to radiator (4) is blocked. The coolant flows through the bypass (3) and back to the water pump (6) .
As the coolant temperature reaches 83° ± 1°C (181° ± 2°F), the water temperature regulator starts to open. Coolant begins to flow to radiator (4). When the coolant temperature reaches 92 °C (198 °F), the coolant is at normal operating temperature. The water temperature regulator is fully open and the flow of coolant to bypass (3) is blocked. The path for coolant to radiator (4) is open. The temperature of the returned coolant will be reduced as the coolant flows through radiator (4) .
Note: The water temperature regulator is an important part of the cooling system. The water temperature regulator divides the coolant flow between radiator (4) and bypass (3). Normal operating temperature is maintained. If the water temperature regulator is not installed in the system, the flow of coolant is not regulated. Most of the coolant will bypass the radiator (4). The engine, the transmission, and the hydraulic oil may overheat during high ambient temperatures.
Radiator Assembly
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| Illustration 2 | g02422337 |
Radiator (Rear View) (7) Hydraulic Oil Cooler | |
Radiator assembly (4) is the source of coolant for the cooling system. The radiator is made up of the following three sections: radiator top tank, radiator bottom tank and radiator core assemblies. Also, radiator assembly (4) includes the air aftercooler and the hydraulic oil cooler (7) .
ReferenceFor additional information about cooling the hydraulic system, refer to the Service Manual module Systems Operation, "Hydraulic Fan System" for the machine that is being serviced.
The radiator top tank accepts the return coolant from the water regulator housing. The coolant flows from the radiator top tank down the tubes of the radiator core. Then, the coolant flows into the bottom tank. As the coolant flows through the radiator core and the air is pulled around the radiator core, the temperature of the coolant is reduced.
Axle Oil Cooler
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| Illustration 3 | g02422338 |
(8) Hydraulic line from hydraulic oil cooler (9) Hydraulic line to hydraulic tank (10) Hydraulic lines to rear axle (11) Divider valve (12) Hydraulic lines to front axle (13) Heat exchanger | |
The axle oil cooler system consists of the following components: divider valve (11), two heat exchangers (13) and hydraulic lines (8, 9, 10, 12) .
The rear axle has a temperature sensor which monitors the axle oil temperature. The contacts for the temperature sensor close when the axle oil reaches the actuation temperature of the sensor. The actuation temperature of the temperature sensor is 125° ± 3° C (257° ± 5° F). When the contacts of the temperature sensor close, an alert indicator in the cab will activate.
The hydraulic oil cooler core mounted on the back of the radiator group continuously supplies cool hydraulic oil to the axle oil cooler system. The hydraulic oil flows through hose assembly (8) to divider valve (11). At divider valve (11), the hydraulic oil flows to the front and rear axles through hydraulic lines (10, 12) .
At each axle, the hydraulic oil flows through heat exchangers (13). Heat from the axle oil is transferred to the hydraulic oil in heat exchangers (13). Then, the hydraulic oil flows through hydraulic lines (10, 12) to divider valve (11). This oil flows through hydraulic lines (9) to the hydraulic tank.
Two bypass check valves for the axle oil cooler system are located in divider valve (11). The bypass check valves limit the oil pressure in heat exchangers (13). The bypass check valves are rated at 170 kPa (25 psi) at 0.95 L/min (0.25 US gpm). If the bypass check valves open, the hydraulic oil bypasses heat exchangers (13) .
Air to Air Aftercooler
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| Illustration 4 | g02422339 |
Air to Air Aftercooler (14) Aftercooler (15) Turbocharger (16) Cooled air enters the air intake manifold on the right side of the machine. (CC) Inlet air | |
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| Illustration 5 | g02422340 |
Air to Air Aftercooler (15) Turbocharger (17) Air cleaner (18) Diesel particulate filter (CC) Inlet air (DD) Exhaust gases | |
The air-to-air aftercooler system (ATAAC system) provides cooled air to air intake manifold (16) on the right side of the machine. Air is drawn in through air cleaner (17) and into turbocharger (15). The air is sent through the tube into aftercooler core (14). From core (14), the air flows into the air intake manifold (16) on the right side of the machine. The air flow from the inlet port into the cylinders is controlled by inlet valves. Each cylinder has inlet valves and exhaust valves in the cylinder head. The inlet valves open when the piston moves downward on the inlet stroke. When the inlet valves open, cooled compressed air from the inlet manifold is pulled into the cylinder. The inlet valves close when the piston begins to move up on the compression stroke. Air is compressed and fuel is injected into the cylinder when the piston is near the top of the compression stroke. Combustion begins when the fuel mixes with the air. The force of combustion pushes the piston downward on the power stroke. The exhaust valves open and the exhaust gases are pushed through the exhaust port.
Exhaust gases from the exhaust manifold flow into the turbine side of the turbocharger (15). The high-pressure exhaust gases cause the turbocharger turbine wheel to rotate. The turbine wheel is connected to the shaft that drives the compressor wheel. Exhaust gases from turbocharger (15) pass through the exhaust outlet, through a diesel particulate filter (18), and through the exhaust stack.
The efficiency of the engine will increase due to the cooler inlet air. This increased efficiency helps to provide lowered fuel consumption and increased horsepower output.