807151A 8 Mercruiser PUMP ASSEMBLY-Sea Water

Cylinder Block
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Cylinder block
The cylinder block is made of cast iron. The cylinder block provides support for the full length of the dry cylinder liners. Cylinder blocks have a flame ring above the cylinder liner flange.The cylinder liners are made of cast iron. The production liners and the replacement liners are a press fit in the cylinder block. Both types of cylinder liners are honed to a specially controlled finish in order to ensure long life and low oil consumption.The cylinder block has a bush that is installed for the front camshaft journal. The other camshaft journals run directly in the cylinder block.D Plug
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Pushrod side of the cylinder block that is showing the D plug
The D plugs are located on the pushrod side of the engine. The D plugs are in the engine block in order to block excessive amounts of oil. The D plug is intended to reduce the amount of oil through the breather hose. The pushrods fit in the cutout of the D plug. Cylinder Head
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Cylinder head
The cylinder head assembly has one inlet valve and one exhaust valve for each cylinder. Each cylinder valve has a single valve spring. The valve and the valve spring are held in position by a valve spring cap and two collets.The inlet valve and the exhaust valve move in phosphated guides. These valve guides can be replaced. There is an oil seal that fits over the top of valve guide.The valve seats are replaceable. The ports for the inlet valve and the exhaust valves are on the right side of the cylinder head.Pistons
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Piston
The pistons have a Fastram combustion chamber in the top of the piston. This chamber ensures an efficient mix of fuel and air.The pistons have two compression rings and an oil control ring. The groove for the top ring has a hard metal insert that reduces wear of the groove. The skirt has a layer of graphite that reduces wear. The off-center piston pin reduces the noise level.The engine has a piston cooling jet that is installed in the cylinder block for each cylinder. The piston cooling jet sprays lubricating oil onto the inner surface of the piston in order to cool the piston.Connecting Rods
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Connecting rod
The connecting rods are machined from forged molybdenum steel. The connecting rod has a small end that has the shape of a wedge.The location of the bearing cap to the connecting rod is made by serrations in both the bearing cap and the connecting rod. The bearing cap is mounted to the connecting rod by two bolts and two nuts.
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Fracture split of the connecting rod
Later engines are equipped with connecting rods that have a fracture split cap. The fracture split caps are retained with torx screws. Connecting rods that are fracture split have the following characteristics:
Higher integrity for the rod
The splitting produces an accurately matched surface on each side for improved strength.
Modern designCrankshaft
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Crankshaft
The crankshaft is a chromium molybdenum forging. The crankshaft has seven main journals.End play of the crankshaft is controlled by two half thrust washers that are located on both sides of the center main bearing.The main bearings are made with a steel back and a bearing material. The bearing material is an alloy. The alloy is constructed of aluminum and of tin. The exception is the center main bearing, which is lead bronze with a lead finish. The main bearing caps are made of cast iron or spheroidal graphite (SG) iron.Vibration Damper
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Vibration damper
(1) Crankshaft
(2) Weight
(3) Case The force from combustion in the cylinders will cause the crankshaft to twist. This is called torsional vibration. If the vibration is too great, the crankshaft will be damaged. The vibration damper limits the torsional vibration. The vibration damper is designed as a viscous damper. The space between the weight and the case is filled with a viscous fluid.Gears and Timing Gear Case