43881A17 Mercruiser GIMBAL HOUSING ASSEMBLY

Main Lubrication System
Under normal operating conditions oil flow is as follows: lubricant from the oil pan base (17) is pumped through oil cooler (7), filter housings (8) and to oil distribution manifold (6).A pressure regulating valve (14) mounted on the oil pan base controls the maximum pressure of oil from pump (16).Oil filter bypass valves in each filter housing, bypass oil to the oil manifold when the flow is momentarily restricted because of cold oil. When the oil is warm, only filtered oil is furnished to the engine bearings. If the oil filter elements become restricted, the bypass valves open and the oil flows directly to the oil distribution manifold.The oil distribution manifold directs oil through connecting passages to the engine internal and external components, timing gears and front accessory drive.External Component Lubrication
The turbocharger, governor, governor booster pump (4), fuel injection pump housing and the governor and fuel pump drive shaft receive lubricant from the fuel pump and governor drive housing oil manifold (3). When equipped with an oil pressure shutoff it is also supplied with lubricating oil from this manifold. Drain back oil from these components returns to the oil pan base.
In this D399 Engine schematic, pressure oil flow is shown in dark grey and suction oil, drain back oil or splash lubricated points are shown in light grey. 1-Turbocharger oil return line. 2-Turbocharger oil supply line. 3-Fuel pump and governor drive housing oil manifold. 4-Governor booster oil pump. 5-Valve rocker mechanism. 6-Oil distribution manifold. 7-Oil cooler. 8-Two filter housings. 9-Camshaft bearings. 10-Crankshaft main bearings. 11-Crankshaft connecting rod bearings. 12-Oil spray orifices. 13-Prelube system pump. 14-Pressure regulating valve. 15-Suction bell. 16-Single section oil pump. 17-Oil pan base.Internal Components
The oil distribution manifold (6) directs filtered lubricant through passages and tubes to: piston oil spray orifices (12), valve rocker mechanism (5), camshaft bearings (9), crankshaft bearings (10), connecting rod bearings (11), fuel pump and governor drive housing oil manifold (3).Timing Gears
Oil under pressure flows to the camshaft thrust bearing. The gears receive lubrication from drain back oil from the turbocharger, camshaft and crankshaft rear bearings.Front Accessory Drive
The oil distribution manifold (1), delivers oil through a drilled passage to the front main bearing, and from this passage to the front accessory drive. Steel tubes in the front accessory drive housing supply oil to the bearings which support the idler gears (7) and (8), water pump gear (2), oil pump gear (3), main idler gear (4) and on D379 Engine the balancer gear (5).
In this schematic pressure oil flow to the accessory drive gear bearings is shown in grey. 1-Oil distribution manifold. 2-Water pump gear. 3-Oil pump gear. 4-Main idler gear. 5-Balancer gear. 6-Crankshaft gear. 7-Idler gear. 8-Idler gear.Oil Pressure
When the engine is running at 1200 RPM with SAE 30 oil, temperature at 200 10°, oil pressure measured at oil pressure gauge hole in V of block should be as indicated in the chart.
7S8875 HYDRAULIC TEST BOXA lower pressure reading, 15 PSI (1,0 kg/cm2), is normal at low idling speeds. An 8M2744 Gauge, which is part of 7S8875 Hydraulic Test Box, can be used for system pressure checking. Turbocharger Lubrication Valve - (D379, D398, G379 and G398 Engines)
When the oil pressure gauge and speed limiter operation indicates adequate oil pressure and bearing failure or wear occurs in both turbochargers, check the turbocharger lubrication valve operation. The valve can be stuck and allow unfiltered oil to constantly lubricate the turbocharger.
EARLIER ENGINE TURBOCHARGER LUBRICATION VALVE LOCATION
LATER ENGINE VALVE AT RIGHT REAR OF ENGINEPrelube System - (D399 and G399 Engines Only)
The prelube system consists of a pump (1) driven by a 115/230 V DC motor (3) switches, valve and adapting lines and fittings. The motor and pump are mounted on the right side of the engine. This system has a separate suction tube in the oil pan base and it discharges oil in the engine oil supply at the tee (2) below the oil cooler.
Major component location of the prelube oil pump system. Components identified are: 1-Oil pump. 2-Tee. 3-Electric motor. 4-Check valve.The prelube pump will start when the diesel engine starting switch is moved to the ON position. When oil pressure of 1-2.5 PSI (0,07-0,18 kg/cm2) is developed in the supply lines to the turbochargers, the switch closes. This energizes the starter solenoid and cranking of the engine begins.When the diesel engine starts and the starting switch is released to stop cranking, the prelube motor stops and engine lubrication is supplied by the engine oil pump. A check valve (4) prevents engine oil pump pressure from circulating oil through the prelube pump during normal engine operation.Prelube Oil Pump Removal and Installation
Lower the crankcase oil level in oil pan base to a level below the base connection of the prelube pump supply tube.Disconnect the battery ground terminal.Remove 110 volt current supply to the pump motor.Disconnect and tag the wires to identify at assembly.Loosen or remove the suction and pressure lines. When all oil lines and switch brackets have been removed or disconnected, support the pump assembly and then remove four bolts to remove the prelube pump and motor.
ELECTRICAL DIAGRAM 32 V STARTING 50 A ALTERNATOR AND 32 V PRELUBEPump weighs approximately 150 lbs. (68 kg).Install in the reverse order of removal. Be sure the check valve is installed to block flow of oil from the engine main oil pump.Prelube Pump Disassembly and Assembly (Later)
When removing the head (3) from the housing (2), use care to avoid damage to any gaskets that may be between the head and housing. Gaskets of .001 in. (0,025 mm), .003 in. (0,076 mm) and .005 in. (0,127 mm) are available for rotor end play adjustment.To install seals (1) use a 1P482 Driver and 1P529 Handle to install them, one at a time, from the head end of the housing. Sealing lips should face away from each other. The hollow head screw (6) should be installed on the outlet side of the rotor (4).
PRELUBE PUMP
1-Seals. 2-Housing. 3-Head. 4-Rotor. 5-Gear.Fill the area between the lips of the seals with grease.