SEAL 2R0039 - Caterpillar

Engine Description
The engine is a diesel engine which is controlled with a mechanically actuated fuel injection pump. The four engine cylinders are arranged in-line.Cylinder Head and Block
The cylinder head assembly has one inlet valve and one exhaust valve for each cylinder. Each valve has a single valve spring and an oil seal. The valve and the valve spring are held in position by a valve spring cap and two retainers. The oil seal fits over the top of the valve guide. The valve seat inserts and the valve guides can be replaced.The ports for the inlet valves are on the right side of the cylinder head. The ports for the exhaust valves are on the left side of the engine.The cylinder block does not have cylinder liners. The cylinder walls are honed.The valve mechanism cover is made from aluminum. The cover contains the following components:
Closed breather assembly
Breather hose
Oil filler cap
Seal between the valve mechanism cover and the cylinder head
Holes for three cap nutsThe cap nuts fit onto studs on brackets. The brackets are mounted on the cylinder head.The gases in the valve cover, which are caused by blowby, pass from the breather assembly through the breather hose into the inlet manifold.Pistons and Connecting Rods
The pistons have a combustion chamber in the top of the piston in order to provide an efficient mix of the fuel and the air. The piston pin is off-center in order to reduce the noise level.The pistons have two compression rings and an oil control ring.The correct piston height is important in order to ensure that the piston does not contact the cylinder head. The correct piston height also ensures the efficient combustion of fuel which is necessary in order to conform to requirements for emissions. The piston must not be machined in order to obtain the correct piston height.A piston and connecting rod are matched to each cylinder. The piston height is controlled by the length of the connecting rod. Three lengths of connecting rods are available in order to attain the correct piston height. The different lengths of connecting rods are made by machining the small end bearing off-center in order to form an eccentric bearing. The amount of the eccentricity of the bearing creates the different lengths of the connecting rods.One height of piston is available. The piston is marked "Std" on the crown. Refer to Testing and Adjusting, "Connecting Rod - Inspect".On a new engine, the cylinder number is etched on the left side of the connecting rod and the cap. The letter that indicates the grade for the connecting rod is also etched on the left side. The letter that is etched on the right side of the connecting rod is the reference number of the manufacturer. The part number on the connecting rod should be toward the front of the engine. Location marks for the main bearings are toward the right side of the engine.Timing Gears, Crankshaft, and Camshafts
The timing case contains the following components:
Front oil seal for