Fuel System

The diaphragm-type fuel transfer pump mounts on the fuel injection pump housing and is driven by a lobe on the injection pump camshaft. The pump draws fuel from the tank and delivers it to a spin-on throw-away type filter. The filter has a combination primary-secondary type construction. A primary fuel filter attachment can be installed between the fuel supply and the transfer pump to strain larger particles from the fuel.

Filtered fuel flows through a shutoff solenoid, mounted on the fuel injection pump housing, into a fuel manifold. The solenoid operates electrically and stops fuel flow when the engine electrical system is shut off.

Fuel in the manifold flows through the barrel assembly inlet port into the area above the injection pump plunger. During injection, the camshaft forces the plunger upward in the barrel. The end of the plunger closes the inlet port and forces the fuel out through high pressure injection lines to the nozzles.

The injection nozzles are located under the valve cover and are held in place by clamps. The nozzle tip projects from the head into the cylinder bore. Atomized fuel is sprayed in a cone-shaped pattern through four .0128 in. (0.325 mm) orifices into the cylinder.

During injection, a small amount of fuel leaks past the valve guide in the nozzle body to lubricate its moving parts. Any excess leakage flows from the nozzle to a fuel return manifold under the valve cover of each cylinder head. External lines connect the manifolds and return the fuel to the tank.

Governor Operation

The hydraulic governor maintains speed at the rpm selected.

When the engine is operating, the balance between the centrifugal force of the revolving weights and the force of the governor spring controls the movement of the valve. The valve directs pressure oil to either side of a rack-positioning piston. Depending upon the position of the valve, the rack is moved to increase or decrease the amount of fuel to the engine to compensate for load variation.

GOVERNOR (Earlier Governor)
1. High idle spring. 2. Weights. 3. Valve. 4. Cylinder. 5. Low idle spring. 6. Piston. 7. Sleeve.

GOVERNOR (Later Governor)
1. Low idle screw. 2. Weights. 3. Valve. 4. Cylinder. 5. High idle spring. 6. Low idle spring. 7. Piston. 8. Sleeve.

Pressurized lubrication oil, directed through passages in the fuel injection pump housing, enters a passage in the governor cylinder. The oil encircles a sleeve within the cylinder. This oil is then directed through a passage in the piston, where it contacts the valve.

When engine load increases, the revolving weights slow down. The weights move toward each other and allow the governor spring to move the valve forward. As the valve moves, a small passage in the piston opens to pressure oil. Oil flows through this passage and fills the chamber behind the piston. The pressure forces the piston and rack forward, increasing the amount of fuel to the engine. Engine rpm increases until the revolving weights rotate fast enough to balance the force of the governor spring.

When engine load decreases, the revolving weights speed up and the toes on the weights move the valve rearward, allowing oil behind the piston to flow through a drain passage opened at the rear of the piston. At the same time, pressure oil between the sleeve and the piston forces the piston and rack rearward. This decreases the amount of fuel to the engine and the engine slows down. When the force of the revolving weights balances governor spring force, engine rpm will be the same as before.

At engine shut down, a low idle spring returns the valve guide and valve to the full load position. This moves the fuel rack to the full travel position, and assures full fuel flow through the fuel injection pump at engine start up.

Injection Nozzle Operation 9L9263 Nozzles

The nozzle is an inward opening, differential hydraulically-operated, hole-type nozzle.

The nozzle body incorporates the inlet fitting, tip and valve guide. The inward opening valve is spring-loaded. Spring preload is adjusted through the pressure adjusting screw; valve lift is controlled by the adjustable lift screw. Both adjusting screws are secured by the locknut. A nylon compression seal under the inlet fitting "banjo" prevents cylinder compression leakage. The carbon dam at the lower end of the body prevents carbon accumulation in the cylinder head bore.

Fuel, under pressure from the injection pump, flows through the inlet, around the valve, filling the nozzle body. When the pressure acting on the differential area overcomes the spring force, the nozzle valve lifts off its seat. Fuel under high pressure sprays through four .0128 in. (0.325 mm) orifices into the cylinder. When delivery to the nozzle ends and pressure drops to the predetermined closing pressure, the spring returns the valve to its seat.

Positive sealing is maintained by line contact of the interference angle between valve and tip seat.

During injection, a small quantity of fuel leaks through a controlled clearance at the valve guide, lubricating all moving parts. This fuel flows through a leak off boot at the top of the nozzle body and returns to the fuel tank.

Injection Nozzle Operation 9L7883 Nozzles

The nozzle is an inward opening, differential hydraulically-operated, hole-type nozzle.

The nozzle body incorporates the inlet fitting, tip and valve guide. The inward opening valve is spring-loaded. Spring preload is adjusted by shims under the pressure screw; valve lift is controlled by the adjustable lift screw. The adjustable lift screw is secured by a locknut. A nylon compression seal under the inlet fitting "banjo" prevents cylinder compression leakage. The carbon dam at the lower end of the body prevents carbon accumulation in the cylinder head bore.

FUEL INJECTION NOZZLE
1. Lift adjusting screw. 2. Locknut. 3. Pressure screw. 4. Spring. 5. Spring seat. 6. Valve guide. 7. Fuel inlet. 8. Compression seal. 9. Valve. 10. Orifices (four). 11. Shims. 12. Nozzle body. 13. Carbon dam. 14. Nozzle tip.

Fuel, under pressure from the injection pump, flows through the inlet, around the valve, filling the nozzle body. When the pressure acting on the differential area overcomes the spring force, the nozzle valve lifts off its seat. Fuel under high pressure sprays through four .0128 in. (0.325 mm) orifices into the cylinder. When delivery to the nozzle ends and pressure drops to the predetermined closing pressure, the spring returns the valve to its seat.

Positive sealing is maintained by line contact of the interference angle between valve and tip seat.

During injection, a small quantity of fuel leaks through a controlled clearance at the valve guide, lubricating all moving parts. This fuel flows through a leak off boot at the top of the nozzle body and returns to the fuel tank.

Fuel Injection Pump Operation

The injection pump plungers and the lifters are lifted by lobes on the camshaft and always make a full stroke. The lifters are held against the cam lobes by spring force applied to the plungers.

Injection begins when the top of the plunger passes and closes the inlet port. The point of injection relates to crankshaft position and is controlled by the lifter assembly thickness. A thicker lifter assembly advances the point of injection and a thinner lifter assembly retards it.

The amount of fuel pumped per stroke is varied by turning the plunger in the barrel. Governor action moves the rack which turns the pump gear segment on the bottom of the plunger.

Automatic Timing Advance Unit Operation (If So Equipped)

Fuel Injection Pump Camshaft Mounted

The automatic timing advance unit is geardriven and mounts on the front of the injection pump camshaft. The drive gear connects to the camshaft through spring loaded sliding weights and a carrier. Two guides, secured to the carrier, fit into two angular slots in the weights. As centrifugal force moves the weights outward against spring pressure, the movement of the slots causes the guides to change the angular relationship between the gear and carrier. This relationship is maintained through the carrier and shaft to the pump camshaft, thereby changing injection timing.

The unit functions from approximately low idle up through rated speed. The amount of timing advance is marked on the unit. It is set at the factory and is not adjustable.

Engine Camshaft Mounted

The automatic timing advance unit mounts on the front of the engine camshaft.

The unit functions from approximately low idle up through rated speed. The amount of timing advance is marked on the unit. It is set at the factory and is not adjustable.

Air Induction And Exhaust

The air inlet system is located on top of the engine. The intake pipe provides a mounting for the air cleaner. The pipe directs air to each cylinder head. The pipe cannot be turned end-for-end because the air cleaner mounting flange sets at a slight angle toward the front of the engine.

The inlet manifolds are integrally cast in the cylinder heads. The manifolding, porting and combustion chamber design generates the air turbulence necessary for complete combustion.

The exhaust system is located on each side of the engine. The exhaust manifolds mount along the outside of the cylinder heads and are not interchangeable.

A positive crankcase ventilator mounts on top of the rocker arm cover. The valve vents crankcase fumes back to the engine through the intake pipe. The rocker arm cover on which the valve mounts is interchangeable between banks. However, the ventilator return pipe fitting must be interchanged with a plug in the intake pipe.

Cylinder Head And Valves

CYLINDER HEAD AND VALVES
1. Push rod. 2. Cam follower. 3. Guide support. 4. Rocker arm shaft. 5. Rocker arm. 6. Exhaust valve. 7. Valve seat insert. 8. Intake valve. 9. Inner valve spring. 10. Outer valve spring.

The cylinder heads are interchangeable among the 4.1 in., 4.5 in., and 5.0 in. stroke engines. In addition, the heads can be used on either the right or left bank by installing a core plug in the unused water outlet in the end of the head. The air inlet manifold is cast into the head.

The camshaft actuates the valve mechanism. A drive gear is secured to the end of the camshaft and driven at one-half engine speed by the crankshaft gear. Five bearings in the cylinder block support the camshaft. A thrust pin, which locates in a groove in the camshaft adjacent to the rear support bearing, positions the shaft and absorbs any thrust.

Solid-type cam followers are located in the cylinder block and follow the cam lobe profile. The push rods transmit the lifting motion to the rocker arms.

The rocker arms mount on the rocker arm shaft. There is a single rocker shaft for each head. The shaft mounts in a support guide which spaces the rocker arms. The entire guide, shaft and rocker arm assemblies can be removed and replaced as a unit. The valve lash must be checked and adjusted, if necessary, after installing the unit.

Each cylinder has one intake and one exhaust valve. The exhaust valve uses a replaceable valve seat insert which is pressed into the cylinder head. The intake valve seat is machined in the head. The air inlet port design above the intake valve seat gives the proper swirl to the incoming air. The valve guide bores are cast integrally and machined in the cylinder head. There are two springs, an inner and outer, per valve. The springs are interchangeable between the intake and exhaust valves.

Lubrication System

Oil moves through the screen and suction tube to the inlet passage in the oil pump cover. The oil pump cover bolts to the back of the engine front cover. The inlet passage directs oil to the pump.

The oil pump is a six lobe, rotor-type. The crankshaft gear drives the outer rotor which rotates in a bearing in the front cover. The inner rotor mounts on a stub shaft in the front cover and is driven by the outer rotor.

A bypass valve in the pump cover senses pump outlet pressure. The valve opens at approximately 72 psi (5.1 kg/cm²) and bypasses oil back to the inlet side of the pump.

Oil from the pump flows through a passage in the front cover to the cylinder block and on to the oil cooler base. The base mounts on the left side of the engine. A valve in the base bypasses oil around the cooler when the oil is cold or the oil cooler restriction is greater than the rest of the system. A 14 to 22 psi (0.89 to 1.55 kg/cm²) pressure differential opens the valve.

Oil from the cooler flows to two spin-on, throw-away filters mounted on the oil cooler base. Each filter contains a bypass valve. If the filters become clogged, oil is bypassed around them. An 18 to 20 psi (1.27 to 1.41 kg/cm²) pressure differential opens the valves.

There are two pressure taps in the oil cooler base. The taps, located on the outlet side of the cooler and filters, are for the oil pressure gauge and a low pressure alarm.

NOTE: On engines equipped with an auxiliary oil filter, the oil supply line connects to the oil cooler base, replacing the cap on the bypass spring retainer.

A drilled passage in the block directs oil from the filters to the oil manifold. The oil manifold is in the vee above the camshaft mounting and extends the length of the block. Oil flows from the manifold to the camshaft bearings. There are grooves in the cylinder block bore around the camshaft bearings. The camshaft journals are lubricated from these grooves through a hole in the bearings. The remaining oil flows around the groove and down through a drilled passage to a hole and a groove in the upper half of the main bearings. Oil from the hole and groove lubricates the main bearing journals.

Oil flows into the crankshaft through holes in the main bearing journals. Drilled passages connect each main bearing journal with the adjacent connecting rod journals. The piston pins are splash lubricated.

The rocker arms receive oil from the oil manifold. Drilled passages in the block align with a passage in each of the cylinder heads. The passage to the left cylinder head intersects the oil manifold near the front of the engine. The passage to the right cylinder head intersects near the rear of the engine.

The passage in each cylinder head aligns with a cavity in the underside of the rocker arm support bracket mounting boss. The cavity is in the front on the left bank and in the rear boss on the right bank. Oil flows to the cavity and up through the boss around the bracket mounting bolts, to the center of the rocker arm shaft. Oil flows along the center of the shaft to the rocker arm bearings. A drilled hole in the rocker arm conveys oil from the bearings toward the ends of the valve stems and push rod sockets. Passages in the head and block drain this oil back to the sump. A second hole in the rocker arm provides pressure oil for the ends of the push rods. Oil drains down along the push rods to lubricate the cam followers and camshaft lobes before returning to the sump.

The fuel injection pump camshaft bearings are lubricated through a passage from the oil manifold. A hole in the camshaft rear bearing opens into a groove on the inside diameter of the bearing. Oil from the groove flows through a drilled hole in the camshaft rear journal and into the center of the camshaft. Holes from the center of the camshaft intersect the front and intermediate bearing journals and lubricate the bearing surfaces. Oil accumulates in the housing until it reaches the level of an opening in the front face of the pump housing. Oil spills out through the opening to splash lubricate the gears in the front cover.

Cooling System

The centrifugal-type water pump mounts on the front cover and is belt driven by the crankshaft pulley. The pump has two outlets. Coolant from the outlet on the right side of the pump flows through a passage in the front cover to the left bank of the engine, and coolant from the outlet on the left flows to the right bank.

The coolant circulates through the block to the cylinder head. Coolant flows from the heads through connecting sleeves to the return manifold in the front cover. Orifices in the sleeves control the flow from the heads.

Part of the coolant to the left bank is diverted from the block to the oil cooler. External lines direct coolant from the block to the cooler and back to the return manifold in the front cover.

An internal passage in the front cover directs the coolant from the return manifold to the water pump inlet. If the thermostats are closed the coolant flows to the pump and is recirculated through the engine. If they are open, coolant flows from the return manifold to the radiator and from there to the pump.

The two thermostats are located at the inlet to the water pump. The inlet-regulated cooling system maintains positive coolant temperature control with decreased engine warm up time.

When the thermostats are closed, coolant is circulated through the block and heads and back to the water pump by way of an internal passage in the front cover. When the thermostats are open, the bypass flow is restricted and the engine coolant flows through the radiator and returns through the inlet elbow to the water pump. Without the thermostats installed, the coolant will continually bypass the radiator, and overheating will result.

The radiator is constructed with a top tank above the core and an expansion tank either above or separate from the top tank. A vent tube connects the radiator top tank and the expansion tank. A cross flow radiator can also be used. The cross flow radiator is constructed with a tank on the left side and a tank on the right side. The expansion tank is either a part of the right side tank, which is separated by an internal baffle, or a tank separate from the radiator. A vent tube connects the expansion tank to the radiator. The expansion tank has a shunt line which connects to the water pump inlet. This shunt system maintains a positive, static head of coolant at the pump inlet to prevent cavitation under all operating conditions. When filling the cooling system, coolant from the expansion tank flows through the shunt line to the water pump inlet and fills the engine block from the bottom. By filling the system from the bottom, air in the system is forced out through the top tank, through the vent tube into the expansion tank.

STANDARD VERTICAL RADIATOR
1. Radiator top tank. 2. Vent tube. 3. Shunt line. 4. Radiator top hose. 5. Engine front cover. 6. Cylinder head. 7. Expansion tank. 8. Radiator bottom tank. 9. Radiator bottom hose. 10. Thermostat housing. 11. Internal bypass. 12. Water pump. 13. Cylinder block.

CROSS FLOW RADIATOR
1. Vent tube. 2. Expansion tank. 3. Radiator right side tank. 4. Radiator top hose. 5. Engine front cover. 6. Cylinder head. 7. Radiator left side tank. 8. Radiator bottom hose. 9. Shunt line. 10. Thermostat housing. 11. Internal bypass. 12. Water pump. 13. Cylinder block.

VERTICAL RADIATOR WITH SEPARATE EXPANSION TANK
1. Radiator top tank. 2. Vent tube. 3. Expansion tank. 4. Shunt line. 5. Engine front cover. 6. Cylinder head. 7. Radiator top hose. 8. Radiator bottom tank. 9. Radiator bottom hose. 10. Thermostat housing. 11. Internal bypass. 12. Water pump. 13. Cylinder block.

CROSS FLOW RADIATOR WITH SEPARATE EXPANSION TANK (Used on Caterpillar Lift Trucks)
1. Radiator left side tank. 2. Radiator top hose. 3. Vent tube. 4. Expansion tank. 5. Shunt line. 6. Engine front cover. 7. Cylinder head. 8. Radiator right side tank. 9. Radiator bottom hose. 10. Thermostat housing. 11. Internal bypass. 12. Water pump. 13. Cylinder block.

Electrical System

Alternator

The alternator is belt driven from the crankshaft pulley. It is a three phase self-rectifying charging unit with three main functional parts: A rotating magnetic field (rotor) which produces flux; a stationary armature (stator) in which alternating current is induced; and stationary rectifying diodes that change alternating current to direct current.

The alternator field current is passed through brushes. The field current is in the order of 2 to 3 amperes. The rectifying diodes will pass current from the alternator to the battery or load, but will not pass current from the battery to the alternator.

ALTERNATOR

Regulator

The separate transistorized voltage regulator is an electronic switching device. It senses the voltage appearing at the oil pressure switch and supplies the necessary field current to maintain the required system voltage. The voltage regulator has two basic "circuits". The "load circuit" conducts positive potential from the regulator input lead, through a diode and transistor, to the regulator output lead, providing the circuit to the rotor (field) winding. The "control circuit" consists of a voltage sensitive zener diode, driver transistor and a voltage divider network. The "control circuit" directs the transistor in the "load circuit" to turn off and on at a rate that will provide the required charging voltage.

Starting Motor

The starting motor is a device used to rotate the flywheel of an engine fast enough to start the engine. A solenoid is used with the starting motor. The action of the solenoid engages the pinion with the ring gear on the engine flywheel when the solenoid is energized. The pinion always engages before the electric contacts in the solenoid close the circuit between the battery and the starting motor.

STARTING MOTOR
1. Field. 2. Solenoid. 3. Clutch. 4. Pinion. 5. Commutator. 6. Brush assembly. 7. Armature.

An overrunning clutch prevents the starting motor from being overspeeded. Releasing the starter switch disengages the pinion from the ring gear of the flywheel. The starting motor is grounded to the engine.

Starter Solenoid

A solenoid is a magnetic switch that utilizes low current to close a high current circuit. The solenoid has an electromagnet with a movable core. There are contacts on the end of the core. The contacts are held open by a spring that pushes the core away from the magnetic center of the coil. Low current will energize the coil and form a magnetic field. The magnetic field draws the core to the center of the coil and the contacts close.

SCHEMATIC OF A SOLENOID
1. Coil. 2. Switch terminal. 3. Battery terminal. 4. Contacts. 5. Spring. 6. Core. 7. Component terminal.

Wiring Diagrams

12 VOLT STARTING AND CHARGING SYSTEM
1. Off, Start Switch. 2. Ammeter. 3. Fuel solenoid. 4. Starter solenoid. 5. Alternator regulator. 6. Starting motor (12V). 7. Pressure switch (normally open). 8. Alternator field terminals. 9. Battery (12V). 10. Hourmeter. 11. Alternator stator terminal. 12. Alternator output terminal. 13. Alternator negative (ground) terminal.