49106 Mercruiser BOLT, (2.00 Inch), CYLINDER HEAD TO CYLINDER BLOCK

oil pump. Engine oil pressure for the lubrication system is supplied by the oil pump. The engine oil pump is located in the front housing. The crankshaft drives the inner rotor of the engine oil pump.The pump has an inner rotor and an outer rotor. The axis of the inner rotor is off-center to the outer rotor. The inner rotor is driven by the crankshaft.The inner rotor has eight lobes which mesh with the nine lobes of the outer rotor. When the pump rotates, the distance increases between the lobes of the outer rotor and the lobes of the inner rotor to create suction. When the distance decreases between the lobes, pressure is created, forcing oil into the lubricating system.The lubricating oil flows from the outlet side of the oil pump through a passage to the plate type oil cooler. The oil cooler is on the right side of the cylinder block. The oil then flows from the oil cooler through a passage to the oil filter head.Under normal conditions, the oil then flows from the oil filter head to the oil filter. The oil may flow through a bypass valve that permits the lubrication system to function if the oil filter becomes blocked.The oil flows from the oil filter through a passage to the front housing. The oil then flows to the oil gallery. The oil gallery is drilled through the total length of the left side of the cylinder block. If the oil filter is on the right side of the engine, the oil flows through a passage that is drilled across the cylinder block to the pressure gallery.Lubricating oil from the oil gallery flows through high-pressure passages to the main bearings of the crankshaft. Then, the oil flows through the passages in the crankshaft to the connecting rod bearing journals. The pistons and the cylinder bores are lubricated by the splash of oil and the oil mist.Engines have piston cooling jets that are supplied with oil from the oil gallery. The piston cooling jets spray lubricating oil on the underside of the pistons to cool the pistons.Lubricating oil from the main bearings flows through passages in the cylinder block to the journals of the camshaft. Then, the oil flows from the rear journal of the camshaft at a reduced pressure to the cylinder head. The oil then flows through the center of the rocker shaft to the rocker arm levers. The valve stems, the valve springs and the valve lifters are lubricated by the splash and the oil mist.The hub of the idler gear is lubricated by oil from the oil gallery. The oil gallery is drilled through the cylinder head and the cylinder block to the rear gear train. The timing gears are lubricated by the splash from the oil.Lubricating oil from the oil filter flows through a passage in the cylinder block to an external feed connection for the turbocharger. The feed connection supplies lubricating oil to the center housing of the turbocharger. Lubricating oil then flows from the drain for the turbocharger to the engine crankcase.