879194T47 Mercruiser PUMP

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
Table 1
Tools Needed    
Part Number     Part Name     Quantity    
1U-5470     Engine Pressure Test Group     1    An oil pressure gauge that has a defect can indicate low oil pressure or high oil pressure.
Illustration 1 g00296486
1U-5470 Engine Pressure Test Group The 1U-5470 Engine Pressure Test Group measures the oil pressure in the system. This Engine Pressure Test Group has a gauge that monitors the oil pressure inside the oil manifold.Note: Refer to Special Instruction, SEHS8907 for additional information on using the 1U-5470 Engine Pressure Test Group.
Illustration 2 g00323033
Location of Oil Pressure Switch (1) Oil pressure switch.
Work carefully around an engine that is running. Engine parts that are hot, or parts that are moving, can cause personal injury.
Oil pressure to the camshaft and main bearings should be checked on each side of the cylinder block at oil gallery plug (1). With the engine at operating temperature, the minimum oil pressure at full load rpm should be approximately 250 kPa (36 psi). Minimum oil pressure at low idle rpm should be approximately 100 kPa (14 psi).
Illustration 3 g00296494
Engine Oil Pressure GraphLow Oil Pressure
Crankcase Oil Level
Check the level of the oil in the crankcase. Add oil if oil is needed. The oil level can possibly be too far below the oil pump supply tube. This will cause the oil pump to NOT have the ability to supply enough lubrication to the engine components.The Oil Pump Does Not Work Correctly
The inlet screen of the supply tube for the oil pump can have a restriction. This restriction will cause cavitation and a loss of oil pressure. Air leakage in the supply side of the oil pump will also cause cavitation and loss of oil pressure. If the bypass valve for the oil pump is held open, the lubrication system can not reach the maximum pressure. Oil pump gears with too much wear cause a reduction in oil pressure.Oil Filter Bypass Valve
If the bypass valve for one or more of the oil filters is held open due to a restriction, a reduction in the oil pressure can be the result. Remove each bypass valve and clean each bypass valve. This allows you to correct the problem. You must also clean each bypass valve bore. Install new Caterpillar oil filters. New filters will prevent more debris from causing this problem.
Caterpillar oil filters are built to Caterpillar specifications. Use of an oil filter not recommended by Caterpillar could result in severe engine damage to the engine bearings, crankshaft, etc., as a result of the larger waste particles from unfiltered oil entering the engine lubricating system. Only use oil filters recommended by Caterpillar.
Excessive Clearance At Engine Bearings Or Open Lubrication System
Components that are worn and components that have too much bearing clearance can cause low oil pressure. Low oil pressure can also be caused by an oil line or by an oil passage that is open, broken, or disconnected.Piston Cooling Jet
The piston cooling jet directs the oil flow to the bottom of the piston when you are operating the engine. This cools the piston. This also provides lubrication for the piston pin. A seizure of the piston will occur quickly if a jet experiences any of the following problems:
Breakage
Restriction
Incorrect installationUse the 5P-8709 Cooling Jet Alignment Tool to check the alignment of the piston cooling jets.High Oil Pressure
Oil pressure will be high if the bypass valve for the oil pump can not be opened.Oil pressure will also be high if the oil filter is plugged with a inoperable filter bypass valve. Foreign matter in the engine oil system could be the cause for the restriction of the oil flow and the movement of the engine oil bypass valves. If the engine oil bypass valves are stuck in the closed position, remove each bypass valve and clean each bypass valve in order to correct this problem. You must also clean each bypass valve bore. Install new engine oil filters. New engine oil filters will prevent more debris from causing this problem.
Caterpillar oil filters are built to Caterpillar specifications. Use of an oil filter not recommended by Caterpillar could result in severe engine damage to the engine bearings, crankshaft, etc., as a result of the larger waste particles from unfiltered oil entering the engine lubricating system. Only use oil filters recommended by Caterpillar.