817427 20 Mercury SCREW (20MM - QTY. OF 3 ON 55)

Illustration 1 g00694432
Lubrication System Schematic
(1) Oil supply to the governor
(2) Oil supply to the rocker arms
(3) Cylinder head gallery
(4) Piston cooling jets
(5) Oil supply to side covers
(6) Camshaft bearing
(7) Passage in carrier housing (4 cylinder engines)
(8) Main oil gallery
(9) Oil supply to the rear support for the balancer unit (4 cylinder engines)
(10) Passage in front housing
(11) Main bearings
(12) Oil supply to camshaft idler gear bearing
(13) Oil supply to turbocharger
(14) Oil supply to oil pump idler gear bearing (6 cylinder engines)
(14) Oil supply to the bearings for the oil pump idler gear and the balancer shaft (4 cylinder engines)
(15) Oil filter bypass valve
(16) Passage
(17) Oil cooler bypass valve
(18) Engine oil filter
(19) Engine oil cooler
(20) Engine oil pan
(21) Oil pump bypass valve
(22) Engine oil pump Engine oil pump (22) is mounted to the bottom of the cylinder block inside the engine oil pan (20). The engine oil pump pulls oil from engine oil pan. The engine oil is then pushed through passage (16) to the engine oil cooler (19). Oil then flows through engine oil filter (18). The filtered oil then enters the turbocharger oil supply line (13) and main oil gallery (8).
Illustration 2 g00694739
Right Side View Of Engine
(13) Turbocharger oil supply line
(15) Oil filter bypass valve
(17) Oil cooler bypass valve
(18) Engine oil filter
(19) Oil cooler
(23) Turbocharger oil return tube The main oil gallery (8) distributes oil to main bearings (11), piston cooling jets (4), and camshaft bearing (6). Oil from the main oil gallery exits the front of the block. The oil then enters passage (10) that is cast in the front housing.The front housing passage sends the oil flow in two directions. At the upper end of the passage (10), oil is directed back into the block and up to cylinder head gallery (3). At the lower end of the passage (10), oil enters passage (14). This passage will send oil to the oil pump idler gear bearing on the 4 cylinder engine and the 6 cylinder engines, and to the bearing for the front bearing for the balancer shaft on the 4 cylinder engine.Oil from the main oil gallery is forced through passages to the crankshaft main bearings. Oil enters the holes in the bearing surfaces (journals) for the main bearing (11). Oil from the front main bearing enters passage (12) in order to lubricate 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. Passages connect the bearing surface (journal) for the main bearing with the bearing surface (journal) for the connecting rod. On the 4 cylinder engine, some of the oil that goes to the rear main bearing is directed out of the rear face of the cylinder block to passage (7) in the crankshaft seal carrier. Oil is then directed into passage (9) in the cylinder block. Oil is supplied to the rear support for the balancer unit in order to lubricate the rear bearings of the balancer unit. A passage in the balancer shafts now carries the oil from the rear balancer shaft bearings to the intermediate bearings of the shafts.
Illustration 3 g00694914
Left Side View Of Engine
(1) Governor oil supply line
(24) Crankcase breather
(25) Location of oil passage for pushrod lifters inside side covers
(26) Hose
(27) Plug Passages (5) send oil from the camshaft bearing (6) to a short oil passage (25) in the side covers. The oil then enters a hole in the shafts of the pushrod lifters in order to lubricate the roller bearings of the lifter.Cylinder head oil gallery (3) provides flow to governor oil supply line (1) and the rocker arm supports. Holes in the rocker arm supports allow lubrication of the valve and injector components.After the lubrication oil's work is done, the lubrication oil returns to the engine oil pan.The oil pump bypass valve (21) limits the pressure of the oil that is coming from the engine oil pump (22). The engine oil pump 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 will open. This allows the oil that is not needed to go back to the suction side of the engine oil pump.The bypass valves (15) and (17) 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 (19) and engine oil filter (18). The engine oil pump (22) sends the cold oil through the bypass valves around the engine oil cooler and the engine oil filter to the turbocharger oil supply line (13) and the main oil gallery (8) 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 (19) or engine oil filter (18). This design allows the engine to be lubricated even though the engine oil cooler or the engine oil filter are restricted.Crankcase breather (24) allows engine blowby to escape from the crankcase. The engine blowby is discharged through hose (26) into the atmosphere. This prevents pressure from building up that could cause seals or gaskets to leak. Oil pressure to the camshaft and the main bearings should be checked at oil gallery plug (27). This plug is located on the left side of the cylinder block.