31704 Mercruiser PLUG, PIPE - DRIVE SHAFT HOUSING (WATER POCKET)

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(1) Alternator (2) Alternator tensioner (3) Supercharger (4) Water pump (5) Supercharger tensioner (6) Clutch (7) Water pump tensioner (8) DamperThe crankshaft drives a pulley that is located behind the damper (8). The crankshaft pulley drives a belt that drives the clutch (6) and the water pump (4). The non-controlled (always driven) section of the clutch (6) drives a belt that drives the alternator (1). The controlled section of the clutch (6) drives a belt that drives the supercharger (3) .Cylinder Block
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The cylinder block provides support for the cylinder liner. The cylinder block also forms the coolant jacket.The cylinder block has seven main bearings. The main bearing caps are fastened to the cylinder block with two bolts for each cap.Removal of the oil pan allows access to the crankshaft, the main bearing caps, the piston cooling jets, and the oil pump.Cylinder Head and Camshaft
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The cylinder head is a one-piece cast iron head. The cylinder head supports the camshaft. Steel reinforced bearings are pressed into each bore. The bearings are lubricated under pressure.The cylinder head is separated from the cylinder block by a nonasbestos fiber gasket with a steel backing. Coolant flows out of the cylinder block through gasket openings and into the cylinder head. This gasket also seals the oil supply and drain passages between the cylinder block and the cylinder head.The air inlet ports are on the right side of the cylinder head, while the exhaust ports are on the left side. There are two inlet valves and two exhaust valves for each cylinder. Replaceable valve guides are pressed into the cylinder head. The electronically controlled fuel injector is located between the four valves. Fuel is injected directly into the cylinders at high pressure. The rocker arm controls the valves.The camshaft has two lobes at each cylinder. These lobes allow the camshaft to operate the exhaust valves and the inlet valves. The camshaft is supported in the cylinder head by seven journals which are fit with bearings. The camshaft is driven by one fixed idler gear which is turned by a cluster idler gear in the rear gear train. The cluster idler gear is driven by the crankshaft. Each bearing journal is lubricated from the oil manifold in the cylinder head. Piston, Rings, and Connecting Rods
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(1) Piston (2) Piston cooling jet (3) Connecting rodThe piston is a one-piece aluminum piston. All of the rings are located above the piston pin bore. The compression ring is a Keystone ring. Keystone rings have a tapered shape. The action of the ring in the piston groove that is tapered helps prevent seizure of the rings. Seizure of the rings is caused by deposits of carbon. The intermediate ring is rectangular with a sharp lower edge. The oil ring is a standard type of ring or a conventional type of ring. Oil returns to the crankcase through slots in the bottom of the groove.Oil from the piston cooling jets sprays the underside of the pistons. The spray lubricates the pistons and the spray cools the pistons. The spray also improves the piston life and the spray also improves the ring life. One spray jet per piston.The connecting rod has a taper on the pin bore end. This taper gives the connecting rod and the piston more strength. The additional strength is concentrated in the areas with the most load. Two bolts hold the connecting rod cap to the connecting rod. This design keeps the connecting rod width to a minimum, so that the connecting rod can be removed through the cylinder. The rod and the original cap must be kept together.Crankshaft
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The crankshaft changes the combustion forces in the cylinder into usable rotating torque. A vibration damper is used at the front of the crankshaft to reduce torsional vibrations (twist on the crankshaft). That force can damage the engine.The crankshaft drives a group of gears on the rear of the engine. The gear group drives the following devices:
Oil pump
Camshaft
High-pressure fuel pump
Seawater pumpA pulley is mounted to the front of the crankshaft. The pulley, idler pulleys, tensioners, and belts drive the following components:
Water pump
Alternator
Belt-driven compressor clutch
Belt-driven compressorVibration Damper
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Cross section of viscous vibration damper (4) Crankshaft (5) Weight (6) CaseThe viscous vibration damper is installed on the front of crankshaft (4). The viscous vibration damper has a weight (5) in a case (6). The space between the weight and the case is filled with a viscous fluid. The weight moves in the case in order to limit the torsional vibration.