861646 Volvo.Penta Plug

Cylinder block
The cylinder block is made of cast iron. The cylinder block provides support for the full length of the dry cylinder liners. Some 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 meet 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 bushing that is installed for the front camshaft journal. The other camshaft journals run directly in the cylinder block.Cylinder head
The cylinder head assembly has one inlet valve and one exhaust valve for each cylinder. Each cylinder valve has a double valve spring or 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 and Connecting Rods
Pistons and Rings
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 are available with different heights.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.Turbocharged engines have 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
The connecting rods are machined from forged molybdenum steel. One type of connecting rod has a small end that has the shape of a wedge. This connecting rod is used on turbocharged engines.The location of the bearing cap to the connecting rod is made by dowels inserted in the bearing cap. The faces of these connecting rods and caps are flat. The cap is mounted to the connecting rod by two bolts.Crankshaft and Vibration Damper
Crankshaft
The crankshaft is a chrome-molybdenum forging. The crankshaft has five main journals for four cylinder engines and seven main journals for six cylinder engines.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 constructed of an aluminum and tin alloy. 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
The vibration damper is designed as a viscous damper.All of the vibration dampers are designed for the suppression of torsional vibrations in the engine crankshaft.Timing Gear Case and Gears
The timing case is constructed of either aluminum or cast iron. The aluminum cover of the timing case contains the front oil seal.The timing gears are made of steel or cast iron. The crankshaft gear drives an upper idler gear and a lower idler gear. The upper idler gear drives the camshaft and the fuel injection pump. The lower idler gear drives the oil pump or the balancer unit. The water pump drive gear is driven by the fuel injection pump. The camshaft and the fuel injection pump rotate at half the engine speed.Camshaft
The engine has a single camshaft. The camshaft is made of cast iron. The camshaft lobes and the eccentric lobe for the transfer pump are chill hardened.The camshaft is driven at the front end. As the camshaft turns, the camshaft lobes move the valve system components. The valve system components move the cylinder valves.The camshaft gear must be timed to the crankshaft gear. The relationship between the lobes and the camshaft gear causes the valves in each cylinder to open at the correct time. The relationship between the lobes and the camshaft gear also causes the valves in each cylinder to close at the correct time.