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| Illustration 1 | g01107127 |
Lubrication system schematic (1) Unit injector hydraulic pump (2) High pressure relief valve (3) Passage to the rocker arms (4) High pressure oil line (5) Injection actuation pressure control valve (6) High pressure oil passages (7) Oil supply line for Unit injector hydraulic pump (8) Piston cooling jets (9) Cylinder head gallery (10) Passage to pushrod lifters (11) Main bearings (12) Camshaft bearing (13) Passage to engine oil pan (14) Main oil gallery (15) Turbocharger oil supply line (16) Passage to front housing (17) Passage to oil pump idler gear bearing (18) Oil filter bypass valve (19) Passage to camshaft idler gear bearing (20) Passage (21) Engine oil filter (22) Oil cooler bypass valve (23) Engine oil cooler (24) Engine oil pump (25) Oil pump bypass valve (26) Engine oil pan | |
Engine oil pump (24) is mounted to the bottom of the cylinder block inside the engine oil pan (26). The engine oil pump (24) pulls oil from engine oil pan (26). The engine oil pump pushes the oil through the passage to the engine oil cooler (23). Oil then flows through engine oil filter (21). The filtered oil then enters the turbocharger oil supply line (15) and main oil gallery (14) .
The main oil gallery (14) distributes oil to main bearings (11), piston cooling jets (8), and camshaft bearing (12). Oil from main oil gallery (14) exits the front of the block. The oil then enters a groove that is cast in the front housing.
Oil enters the crankshaft through holes in the bearing surfaces (journals) for the main bearing (11). Passages connect the bearing surface (journal) for the main bearing (11) with the bearing surface (journal) for the connecting rod.
The front housing passage sends the oil flow in two directions. At the upper end of the passage, oil is directed back into the block and up to cylinder head gallery (9) through a passage to the rocker arm (3). Passage (17) sends oil to the oil pump idler gear bearing.
Oil from the front main bearing enters a passage (19) to the camshaft idler gear bearing. Oil passages in the crankshaft send oil from all the main bearings (11) through the connecting rods to the connecting rod bearings.
The passages send oil from the camshaft bearing (12) to an oil passage in the side covers. The oil then enters a hole in the shafts to pushrod lifters (10). The oil lubricates the bearings of the lifter.
The Unit injector hydraulic pump (1) is a gear-driven axial piston pump. The Unit injector hydraulic pump raises the engine oil pressure from the typical operating oil pressure to the actuation pressure that is required by the unit injectors. The injection actuation pressure control valve (5) electronically controls the output pressure of the Unit injector hydraulic pump (1) .
The oil circuit consists of a low pressure circuit and a high pressure circuit. The low pressure circuit typically operates at a pressure of 240 kPa (35 psi) to 310 kPa (45 psi). The low pressure circuit provides engine oil that has been filtered to the Unit injector hydraulic pump (1). Also, the low pressure circuit provides engine oil that has been filtered to the lubricating system of the engine. Oil is drawn from the engine oil pan (26). Oil is supplied through the engine oil cooler (23) and engine oil filter (21) to both the engine and the Unit injector hydraulic pump (1) .
The high pressure oil system provides actuation oil to the unit injector. The high pressure circuit operates in a pressure range typically between 4 MPa (580 psi) and 23 MPa (3350 psi). This high pressure oil flows through a line into the cylinder head. The cylinder head stores the oil at actuation pressure. The oil is ready to actuate the unit injector. Oil is discharged from the unit injector under the valve cover so that no return lines are required.
After the lubrication oil's work is done, the lubrication oil returns to the engine oil pan.
The oil pump bypass valve (25) limits the pressure of the oil that is coming from the engine oil pump (24). The engine oil pump (24) can pump more than enough oil into the system. When there is more than enough oil, the oil pressure increases. When the oil pressure increases, the oil pump bypass valve (25) will open. This allows the oil that is not needed to go back to the suction side of the engine oil pump (24) .
Oil filter bypass valve (18) and oil cooler bypass valve (22) will open when the engine is cold (starting conditions). Opening the bypass valves achieves immediate lubrication of all components. Immediate lubrication is critical when cold oil with high viscosity causes a restriction to the oil flow through engine oil cooler (23) and engine oil filter (21). The engine oil pump (24) sends the cold oil through the bypass valves around the engine oil cooler (23) and engine oil filter (21) to the turbocharger oil supply line (15) and the main oil gallery (14) in the cylinder block.
When the oil gets warm, the pressure difference in the bypass valves decreases and the bypass valves close. After the bypass valves close, there is a normal flow of oil through the engine oil cooler and the engine oil filter.
The bypass valves will also open when there is a restriction in the engine oil cooler (23) or engine oil filter (21). This design allows the engine to be lubricated even though engine oil cooler (23) or engine oil filter (21) are restricted.
High pressure relief valve (2) regulates high pressure in the system. When the oil pressure is at 695 kPa (100 psi) or more, high pressure relief valve (2) will allow oil to return to engine oil pan (26) .
The oil flow continues to the engine oil cooler (23). Coolant flows through engine oil cooler (23) in order to cool the oil. When the temperature of the oil exceeds 100 °C (212 °F), the internal thermostat in oil cooler bypass valve (22) directs the oil flow through the engine oil cooler (23) .
Oil cooler bypass valve (22) has a temperature sensitive link that will close the valve when the oil reaches a certain temperature. Closing the valve directs oil flow to the engine oil cooler (23). The maximum activation temperature of the bypass valve is 127 °C (260 °F). If the valve fails, the valve will remain closed. The bypass valve is also activated by pressure. If the oil pressure differential across the engine oil cooler reaches 155 ± 17 kPa (22 ± 2 psi), the valve will open. Opening the valve allows the oil flow to bypass the engine oil cooler (24) .
Approximately five percent of the oil flow is directed through an orificed passage to oil filter bypass valve (18). The oil flow now reaches the engine oil filter (21). When the oil pressure differential across the oil filter bypass valve (18) reaches 170 kPa (25 psi), the valve opens in order to allow the oil flow to go around the oil filter (21). The oil flow continues in order to lubricate the engine components. When the oil is cold, an oil pressure difference in the bypass valve also causes the valve to open. This bypass valve then provides immediate lubrication to all the engine components when cold oil with high viscosity causes a restriction to the oil flow through the engine oil filter (21). The bypass valve will also open when there is a restriction in the engine oil filter (21). This design allows the engine to be lubricated even though engine oil filter (21) is restricted.
Filtered oil flows through the main oil gallery (14) in the cylinder block. Oil is supplied from the main oil gallery (14) to the following components:
- Piston cooling jets (8)
- Valve mechanism
- Camshaft bearing (12)
- Crankshaft main bearings
- Turbocharger cartridge
An oil cooling chamber is formed by the lip that is forged at the top of the skirt of the piston and the cavity that is behind the ring grooves in the crown. Oil flow for the piston cooling jet enters the cooling chamber through a drilled passage in the skirt. Oil flow from the piston cooling jet returns to the engine oil pan (26) through the clearance gap between the crown and the skirt. Four holes that are drilled from the piston oil ring groove to the interior of the piston drain excess oil from the oil ring.
The closed crankcase ventilation system is incorporated within the air cleaner. The closed crankcase ventilation system eliminates oil vapors in the engine room. The closed crankcase ventilation system separates the oil from the gases, returning the oil to the crankcase and directing the dry gases to the inlet air.
The system is entirely enclosed and virtually maintenance free. Refer to the Operation and Maintenance Manual for the maintenance interval for the air filter element. The system consists of three major components: air cleaner, vacuum limiter and separator housing. The air filter can be removed, cleaned, and reused.
As inlet air passes through the air cleaner to the turbocharger, a slight vacuum is created within the separator housing. The fumes from the crankcase are drawn through the crankcase breather. The fumes pass through a hose that connects the crankcase breather to the low pressure side of the separator housing. Once in the separator housing, the oil vapor is removed from the gases and returned to the crankcase through a drain line. The gases are drawn into the inlet side of the turbocharger through the air cleaner. The vacuum in the crankcase is maintained at 0.4 kPa (1.6 inch of H2O) by the vacuum limiter. A check valve in the oil drain line prevents oil from being drawn into the separator. As the restriction in the air filter builds up, fresh air is drawn in through the vacuum limiter. The vacuum limiter maintains the 0.4 kPa (1.6 inch of H2O) of vacuum in the crankcase.