MOTOR ASSEM. 8N4903 - Caterpillar

Illustration 1 g02191598
Lubrication system schematic (typical example)
(1) Main engine oil gallery
(2) Engine oil gallery for the left camshaft
(3) Engine oil gallery for the right camshaft
(4) Engine oil gallery for the piston cooling jets
(5) Piston cooling jet
(6) Engine oil supply for the turbochargers
(7) Sequence valve
(8) Sequence valve
(9) Adapter
(10) Engine oil filter base
(11) Engine oil cooler
(12) Bypass valve
(13) Relief valve
(14) Engine oil pump
(15) Elbow
(16) Suction bell
(17) Engine oil filterEngine oil pump (14) has three gears that are driven by the front gear train. The engine oil pump pulls engine oil from the pan through suction bell (16) and elbow (15). The suction bell has a screen to strain the engine oil.Relief valve (13) controls the maximum pressure of the engine oil from the engine oil pump. If the pressure from the pump becomes excessive, the relief valve opens and some of the engine oil recirculates back to the inlet.Engine oil cooler (11) reduces the temperature of the engine oil. The engine oil cooler has bypass valve (12) that is designed to open if the cooler becomes restricted.
Illustration 2 g06098003
(17) Engine oil filter housingEngine oil filter housing (17) contains the oil filter. The housing has an internal bypass valve.The bypass valve will open if there is a restriction in the engine oil filter. The bypass allows the engine to be lubricated if the engine oil filter is restricted.Clean engine oil from the engine oil filters goes through adapter (9) into the block. Part of the engine oil goes to left camshaft oil gallery (2). The remainder of the engine oil goes to main engine oil gallery (1).Engine oil galleries (2) and (3) supply engine oil through drilled passages to the camshaft bearings. The engine oil circulates around each camshaft journal. The engine oil then flows through the cylinder head and through the rocker arm housing to the rocker arm shaft. Some of the engine oil lubricates the valve stems. The remainder of the engine oil drains from the cylinder head to lubricate the pushrods, the valve lifters, the camshaft, and the camshaft bearings.Engine oil from main engine oil gallery (1) is supplied to the main bearings through drilled passages. Drilled holes in the crankshaft supply engine oil from the main bearings to the connecting rod bearings. Engine oil from the rear of the main engine oil gallery goes to the rear of right camshaft oil gallery (3).Sequence valves (7) and (8) allow engine oil from main engine oil gallery (1) to enter engine oil galleries (4) for piston cooling jets (5). The sequence valves will not allow engine oil into gallery (4) for the piston cooling jets until there is pressure in the main engine oil gallery. This action reduces the amount of time that is required for pressure buildup when the engine is started.
Illustration 3 g00928859
(5) Piston cooling jetPiston cooling jet (5) is located in the engine block below each piston. Each piston cooling jet has two tubes with open ends. One tube directs engine oil into an opening in the bottom of