955568 Volvo.Penta Hexagon screw

Illustration 1 g01448759
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) High pressure oil manifold
(6) Passage from high pressure oil manifold to injector
(7) Oil supply line for unit injector hydraulic pump
(8) Piston cooling jets
(9) Cylinder head gallery
(10) Passage to pushrod lifters
(11) Main bearing
(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) Auxiliary engine oil filter (if equipped)
(27) Engine oil pan Engine oil pump (24) is mounted to the bottom of the cylinder block inside the engine oil pan (27). The engine oil pump (24) pulls oil from engine oil pan (27). 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 front housing (16).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 passage in front housing (16) 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 passage (3) to the rocker arm mechanism. A 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.Note: Engines that are equipped with an auxiliary oil filter (26) will receive oil at a port. The filtered oil will be returned to engine oil pan (27).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 480 kPa (70 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 (27). 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 6 MPa (870 psi) and 28 MPa (4050 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).The bypass valves (22) and (18) 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.The engine oil cooler bypass valve is also activated by pressure. If the oil pressure differential across the engine oil cooler reaches 125 30