32515 Mercruiser SCREW, (.437-20 x 2.50)

FLOW OF LUBRICATING OIL (16 Motor Grader Illustrated)
1-Camshaft rear bearing. 2-Camshaft follower. 3-Camshaft lobe. 4-Turbocharger oil supply line. 5-Turbocharger bearings. 6-Turbocharger oil return line. 7-Speed limiter plunger. 8-Passage in governor. 9-Camshaft oil supply passage. 10-Oil pressure gauge line. 11-Oil filters. 12-Fuel injection pump housing oil manifold. 13-Spray jet. 14-Drilled passage. 15-Oil pump drive. 16-Oil filter base. 17-Oil cooler bypass line. 18-Scavenge tube. 19-Oil pump drive shaft. 20-Oil cooler. 21-Scavenge pump. 22-Main oil pump. 23-Suction bell on oil pump.A positive displacement, gear-type oil pump, driven from the crankshaft gear, circulates the lubricant through the system.The lubricant serves a number of functions. It lubricates the entire engine and a number of the accessories, including the governor, turbocharger and a portion of the fuel injection system. The pressure in the system provides a boost to governor operation and actuates the speed limiter.The system includes a full flow oil filter with a turbocharger lubrication valve, oil cooler bypass valve and oil filter bypass valve located in the base of the filter housing. An oil cooler is provided for cooling the lubricant.Fuel System
FLOW OF FUEL SCHEMATIC
1-Supply tank. 2-Return line. 3-Bypass valve. 4-Pressure gauge. 5-Fuel filter. 6-Fuel injection line. 7-Fuel injection nozzle. 8-Air bleed manifold. 9-Fuel manifold. 10-Supply line. 11-Air bleed passage. 12-Air vent valve. 13-Vent line. 14-Primary filter. 15-Priming pump. 16-Transfer pump.Fuel for the diesel engine fuel system is pumped from fuel supply tank (1) through supply line (10) and filter (14), by transfer pump (16), located on the bottom of the fuel injection pump housing.Transfer pump (16) forces fuel through the fuel injection pump housing adapter and fuel filter housing cover to fuel filters (5). A spring-loaded bypass valve (3), located in the housing adapter, maintains approximately 25 pounds fuel pressure in the fuel filter housing and fuel injection pump housing. Excess fuel supplied by the pump is bypassed through return line (2) to supply tank (1).After passing through the fuel filters, fuel flows through passages in the filter housing cover and adapter to fuel manifold (9), which distributes fuel to the fuel injection pumps.A cam-actuated injection pump for each cylinder forces fuel through an injection line (6) to injection nozzle (7). A definite quantity of fuel is forced into the precombustion chamber by the injection pump at the proper time.Air vent valve (12), located on the adapter between the filters and the injection pump housing, is provided to vent the trapped air from the entire fuel system. When the vent valve is opened, and fuel is caused to flow by action of either the transfer pump or a priming pump, air and fuel escapes through vent line (13). Air bleed passage (11) allows the air to escape from the top of the fuel filter housing cover, and air bleed manifold (8) allows the air to escape from the injection pump housing.When the fuel system is vented, the bleed valve should be left open until a solid stream of fuel flows out the drain tube, indicating that all air has been bled from the system.Fuel pressure gauge (4) is connected to the top of the fuel filter housing cover. Lack of pressure on the gauge indicates difficulty in the supply side of the system.Fuel Injection Pumps
Trapped air in the fuel system bleeds through passage (2) when the vent valve is opened. Fuel enters through passage (6). Injection pump plungers (4) and lifters (8) are actuated by lobes on camshaft (9), and always make a full stroke. Each pump (1) measures the amount of fuel to be injected into its respective cylinder and delivers it to the fuel injection valve. The amount of fuel pumped per stroke is varied by turning the plunger in the barrel. The plunger is turned by rack (7) which meshes with gear segment (5) on the bottom of the pump plunger.
FUEL INJECTION PUMP
1-Pump. 2-Bleed passage. 3-Inlet port. 4-Pump plunger. 5-Gear segment. 6-Fuel passage. 7-Rack. 8-Lifter. 9-Camshaft.Figures A, B and C illustrate the functioning of an injection pump as the plunger makes a stroke. In Fig. A the plunger is down and inlet port (3) is uncovered. Fuel flows into the space above the plunger through the slot, and into the recess around the plunger.In Fig. B the plunger has started up and the port is covered. The fuel is trapped and will be forced through the check valve, fuel line, and injection valve, as the plunger moves upward.In Fig. C the plunger has risen until the port is uncovered by the recess in the plunger. The fuel can now escape back through the port into the fuel manifold and injection will cease.It will be noted that the recess in the pump plunger forms a helix around the upper end of the plunger. Figures D, E and F illustrate how rotating the pump plunger affects the quantity of fuel injected. In Fig. D the plunger has been rotated into the shutoff position. The slot connecting the top of the plunger with the recess is in line with the port, therefore, no fuel can be trapped and injected.In Fig. E the plunger has been rotated into the idling position. The narrow part of the plunger formed by the helix will cover the port for only a short part of the stroke. This permits only a small amount of fuel to be injected per stroke.In Fig. F the plunger has been rotated into the full load position. The wide part of the plunger formed by the helix covers the port for a longer part of the stroke. This permits a larger amount of fuel to be injected per stroke.Speed Sensing Variable Timing Unit (Machines so Equipped)
SPEED SENSING VARIABLE TIMING UNIT
1-Timing unit idler gear. 2-Washer. 3-Housing. 4-Adapter assembly. 5-Carrier assembly. 6-Guide assembly (two). 7-Block (two). 8-Bearing. 9-Cover. 10-Adapter. 11-Retainer plate. 12-Gear assembly. 13-Weight (two). 14-Spring (two). 15-Shaft assembly. 16-Coupling. 17-Timing dowel.The speed sensing variable timing unit, which is mounted in the timing gear housing and driven by the timing gears, moves the fuel injection pump camshaft in relation to the drive gear.