INSERT-VALVE SEAT 4W4325 - Caterpillar

Cylinder Block And Head
The cylinder block has seven main bearings. The main bearing caps are fastened to the cylinder block with two bolts per cap.Removal of the oil pan allows access to the crankshaft, the main bearing caps, the piston cooling jets, and the oil pump.The camshaft is accessible through the covers on the left side of the cylinder block. These side covers support the pushrod lifters. The camshaft is supported by bearings that are pressed into the cylinder block. There are seven camshaft bearings.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 left side of the cylinder head, while the exhaust ports are located on the right side of the cylinder head. There are two inlet valves and one exhaust valve for each cylinder. Replaceable valve guides are pressed into the cylinder head. The hydraulically actuated electronically controlled unit injector is located between the three valves. Fuel is injected directly into the cylinders at very high pressure. A pushrod valve system controls the valves. Piston, Rings And Connecting Rods
High output engines with high cylinder pressures require two-piece articulated pistons. Refer to the Parts Manual in order to obtain information about the type of pistons that are used in a specific engine.The two-piece articulated piston consists of an alloy forged steel crown that is connected to an aluminum skirt by the piston pin. The two-piece articulated piston has three rings:
a compression ring
an intermediate ring
an oil ringAll 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 holes in the oil ring 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's life and the spray also improves the ring's life.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.Crankshaft
The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the equipment. A vibration damper is used at the front