Metric Fasteners

NOTE: Take care to avoid mixing metric and inch fasteners. Mismatched or incorrect fasteners can result in mechanical damage or malfunction, or possible personal injury. Original fasteners removed during disassembly should be saved for assembly when possible. If new ones are required, caution must be taken to replace with one that is of same part number and grade.

Metric thread fasteners are identified by material strength (grade) numbers on bolt heads and nuts. Numbers on bolts will be 8.8, 10.9, etc. Numbers on nuts will be 8, 10, etc.

Engine Design

3116 Cylinder And Valve Location

Bore ... 105.025 ± 0.025 mm (4.1348 ± .0010 in)

Stroke ... 127 mm (5.0 in)

Displacement ... 6.6 liter (403 cu in)

Number Of Cylinders ... 6

Cylinder Arrangement ... in-line

Valves Per Cylinder ... 2

Valve Clearance Setting

Intake ... 0.38 mm (.015 in)

Exhaust ... 0.64 mm (.025 in)

Type of Combustion ... Direct Injection

Firing Order ... 1-5-3-6-2-4

Direction of Crankshaft Rotation (when seen from flywheel end) ... counterclockwise

NOTE: Front end of engine is opposite the flywheel end. Left side and right side of engine are as seen from flywheel end. No. 1 cylinder is the front cylinder.

Fuel System

Fuel System Schematic
(1) Screen. (2) Inlet check valve. (3) Fuel transfer pump (integral with governor). (4) Outlet check valve. (5) Fuel filter. (6) Cylinder head. (7) Pressure regulating orifice. (8) Check Valve. (9) Primary fuel filter (if equipped). (10) Fuel tank. (A) Fuel priming pump (if equipped).

Fuel from the fuel tank is pulled through an in-line screen (1) by fuel transfer pump (3). The fuel transfer pump is integral with the governor. Fuel is sent from the fuel transfer pump through fuel filter (5) and to a drilled passage in cylinder head (6). The drilled passage intersects a gallery around each unit injector to provide a continuous flow of fuel to all injectors. Unused fuel exits the cylinder head and passes through pressure regulating orifice (7) and check valve (8) before returning to fuel tank (10). Orifice (7) is located in the fuel return tube assembly. This pressure regulating orifice ensures adequate fuel gallery pressure for low idle fuel flows. Check valve (8) prevents bleed-off of fuel from the cylinder head during engine shutdown.

When there is air on the inlet side of the fuel system, fuel priming pump (A) (if equipped) may be used to fill the fuel filter and fuel gallery (in the cylinder head), from the fuel tank before the engine is started. When the priming pump is used, check valves located in the fuel priming pump control the movement of fuel through the low pressure side of the system which removes air from the fuel lines and components back into the fuel tank.

Fuel Filter Lines Group
(3) Fuel transfer pump (integral with governor). (5) Fuel filter. (6) Cylinder head. (11) Fuel outlet port (to tank). (12) Fuel inlet port (to fuel transfer pump). (13) Fuel filter base. (14) Filtered fuel pressure tap. (15) Tube assembly (from fuel filter base to cylinder head fuel gallery in cylinder head). (16) Tube assembly (from transfer pump to fuel filter base).

Fuel Filter Lines Group (View A-A)
(1) Screen. (6) Cylinder head. (7) Pressure regulating orifice. (8) Check Valve. (11) Fuel outlet port (to tank). (12) Fuel inlet port (to fuel transfer pump). (16) Tube assembly (from transfer pump to fuel filter base). (17) Tube assembly (return to tank from fuel passage in cylinder head).

Fuel Transfer Pump

Fuel Transfer Pump
(1) Screen. (2) Inlet check valve. (3) Spring. (4) Piston assembly. (5) Outlet check valve. (6) Piston check valve. (7) Tappet assembly. (8) Cam. (9) Passage.

The fuel transfer pump is located in the front housing of the governor. The pump is activated by cam (8) attached to the shaft of the governor drive gear. Piston assembly (4) and tappet assembly (7) are stroked up and down by cam (8) and spring (3).

Fuel enters the transfer pump through screen (1) and inlet check valve (2). On the upstroke of piston assembly (4), inlet check valve (2) closes. Outlet check valve (5) closes to prevent fuel from being pulled back in the pump from the outlet. As pressure increases above piston assembly (4), piston check valve (6) opens to allow fuel to fill passage (9).

On the downstroke, increasing fuel pressure in passage (9) causes piston check valve (6) to close and outlet check valve (5) to open, pushing fuel to the main fuel filter and engine. Inlet check valve (2) opens to allow fuel to fill the cavity above piston assembly (4).

During engine shutdown, the check valves are held closed by springs.

Fuel Injector

Fuel Injection System
(1) Rocker arm. (2) Setscrew. (3) Follower. (4) Tappet spring. (5) Push rod. (6) Plunger. (7) Rack. (8) O-ring. (9) Barrel. (10) Fuel gallery. (11) Sleeve. (12) O-ring. (13) Lifter. (14) Cam.

The fuel injection pump (unit injector) allows a small amount of fuel to be injected at the proper time into the combustion chamber. The fuel is supplied by fuel gallery (10) around each injector. Each of these galleries is connected by a drilled passage in the cylinder head. This passage provides a continuous flow of fuel to all unit injectors.

The unit injector is isolated from the coolant passage by sleeve (11). This sleeve also provides the seating surface for the injector.

Injection timing is determined by the angular location of cam (14) and the vertical location of plunger (6) in barrel (9). The angular location of the cam is controlled by the camshaft to crankshaft gear mesh at the front of the engine. The location of the plunger (fuel timing) is adjusted by setscrew (2).

As the camshaft rotates, its profile is sent to rocker arm (1) by lifter (13) and push rod (5). The motion of rocker arm (1) is then sent to plunger (6) through follower (3).

Fuel Injector Pump (Unit Injector)
(4) Tappet spring. (6) Plunger. (7) Rack. (9) Barrel. (12) O-ring. (15) Gear. (16) Sleeve filter. (17) Helix. (18) Lower port. (19) Upper port. (20) Spring. (21) Check (needle valve).

At the top of the plunger's stroke, fuel from fuel gallery (10) enters the injector around the edges of sleeve filter (16). The fuel then fills the volume below plunger (6).

During the plunger's downward motion, fuel beneath the plunger is displaced into the gallery through the two ports in barrel (9). As upper port (19) is closed by the bottom edge of the plunger, fuel continues to be displaced through lower port (18). When the lower port is closed, effective stroke begins and the fuel inside the injector becomes pressurized by the continued downward movement of the plunger. When the fuel pressure is sufficient to open check (21), high pressure fuel will be forced through the orifices at the bottom of the nozzle into the combustion chamber. This will continue until upper port (19) is uncovered by helix (17) on the plunger. At this instant, effective stroke ends and this high pressure fuel will spill through upper port (19) into the gallery allowing spring (20) to close check (21). This will end the injection cycle.

The plunger will continue its downward movement until the lifter (13) reaches the nose of the cam. Then the plunger will be returned upward by tappet spring (4) causing the cavity under the plunger to be refilled from the fuel in the gallery. Now the injector is ready for the next cycle.

In addition to vertical motion, the plunger can rotate with respect to barrel (9) by gear (15). This gear, which slides to allow vertical movement of the plunger, meshes with rack (7). The rotation of the gear changes the relationship between helix (17) and upper port (19). The amount of fuel injected into each combustion chamber then changes. For example, if rack (7) is moved to the right, plunger (6) rotates CCW (from top). The distance between the bottom end of the plunger and helix (17) then increases with respect to upper port (19). Thus the effective stroke is increased and more fuel is injected into the combustion chamber.

Fuel Injector Rack Control Linkage

Injectors And Rack Control Linkage
(1) Shaft. (2) Spring. (3) Clamp. (4) Link. (5) Fuel setting screw. (6) Lever assembly. (7) Lever assembly. (8) Synchronization screw. (9) Clamp assembly. (10) Rack. (11) Injector.

View A-A From Injectors And Rack Control Linkage (Previous) Illustration
(1) Shaft. (3) Clamp. (7) Lever assembly. (8) Synchronization screw. (10) Rack. (11) Injector.

The rack control linkage connects the governor output to fuel injector (11) at each cylinder. The governor output shaft is pinned to link (4). Link (4) is connected to lever assembly (6). When the governor demands more fuel, link (4) and lever assembly (6) cause FUEL ON rotation of shaft (1) and clamps (3). Each clamp then pushes lever assembly (7) as the shaft rotates. Fuel Injector rack (10) is pulled by lever assembly (7), allowing more fuel to be injected into the cylinder.

When the governor demands less fuel, link (4) causes shaft (1) and clamps (3) to rotate in the FUEL OFF direction. Torsion spring (2) then forces lever assembly (7) to also rotate clockwise, pushing injector rack (10) toward shutoff. Torsion spring (2), at each lever assembly (7), allows the rack control linkage to go to shutoff, even if one injector rack is stuck open.

Power setting of the No. 1 cylinder injector is made with fuel setting screw (5) in clamp assembly (9). As fuel setting screw (5) is turned, shaft (1) rotates to a new position with respect to link (4) and lever assembly (6). Adjusting screws (8) allow synchronization of the injectors to the injector of No. 1 cylinder.

Governor

The governor transfers the operator's requirements to the fuel injector rack control linkage. The governor receives the desired engine speed by the position of the throttle. The governor output shaft immediately moves when the throttle is moved. The motion of the governor output shaft then causes the injector rack control linkage to rotate and move the injector racks. As engine speed changes because of the rack change, the governor adjusts the amount of fuel delivered. This causes the engine to stabilize at the speed corresponding to the throttle position.

Governor
(1) Governor drive gear. (2) Shaft. (3) Flyweight carrier. (4) Flyweights. (5) Riser. (6) Low idle spring. (7) High idle spring. (8) Shaft. (A) Pin.

The governor senses engine speed from the camshaft through governor drive gear (1). Shaft (2) connects the governor drive gear to flyweight carrier (3). As flyweights (4) rotate, a centrifugal force is created. This force is converted to linear motion, moving riser (5) toward low and high idle springs (6 and 7) when engine speed increases. At low idle speed, spring (6) exerts an opposite force on riser (5). At high speed, spring (7) also becomes compressed. When the engine speed decreases, springs (6 and 7) move riser (5) toward the flyweights. Thus, there is a unique riser position for every engine speed. This feature makes this a "full range" governor. The riser position provides the speed position for the rest of the governor.

NOTE: Pin (A), located on riser lever (18) (see governor schematic that follows), engages in riser (5).

Governor Schematic
(9) Governor output shaft. (10) Limit lever setscrew. (11) Throttle lever. (12) Fulcrum lever. (13) Pivot lever. (14) Limit lever. (15) Torque lever. (16) Torque cam. (17) Pivot shaft. (18) Riser lever.

As riser (5) moves, riser lever (18) causes pivot shaft (17) to rotate. Pivot lever (13) rotates with the pivot shaft and, like riser (5), will have a unique position for every engine speed.

The operator selects the desired speed through throttle lever (11). The throttle lever and governor output shaft (9) are connected by fulcrum lever (12), which is pinned to pivot lever (13). This connection provides the operator with a direct communication to the governor output. As the engine speed changes, fulcrum lever (12) moves to change the governor output to a new stable condition. The same condition occurs when the operator changes the position of throttle lever (11).

The following illustrations show how fulcrum lever (12) allows engine speed and operator input to affect governor output.

Example A Stable operation at low idle.
(11) Throttle lever. (12) Fulcrum lever. (17) Pivot shaft. (18) Riser lever. (19) Path of fulcrum pin. (20) Fulcrum pin. (21) Low idle stop.

Example B
Input position increased toward high idle causing an increase in fuel.
(11) Throttle lever. (12) Fulcrum lever. (17) Pivot shaft. (18) Riser lever. (19) Path of fulcrum pin. (20) Fulcrum pin. (22) High idle stop.

Example C
Engine speed becomes stable at high idle resulting in a new riser position which decreases the amount of fuel.
(11) Throttle lever. (12) Fulcrum lever. (17) Pivot shaft. (18) Riser lever. (19) Path of fulcrum pin. (20) Fulcrum pin. (22) High idle stop.

Example D
As the engine is loaded and the speed is decreasing, the riser is seeking a new position causing the fuel to increase.
(11) Throttle lever. (12) Fulcrum lever. (17) Pivot shaft. (18) Riser lever. (19) Path of fulcrum pin. (20) Fulcrum pin. (22) High idle stop.

The governor limits the fuel injected into the combustion chamber when rated load or a lug condition is reached. When this condition occurs, limit lever (14) is against limit lever setscrew (10) and output shaft (9) is in the maximum FUEL ON position. Torque lever (15) has rotated about a pin on limit lever (14) until the torque lever contacts torque cam (16). If more load is applied to the engine in this condition, engine speed will decrease. This decrease will be felt by the flyweights, causing riser (5) to rotate riser lever (18) and pivot shaft (17) to a new position. Since torque cam (16) is fixed to pivot shaft (17), different torque characteristics can be achieved by changing the profile on the torque cam.

The governor is lubricated by engine oil. An oil supply line delivers oil to the governor from the cylinder head oil gallery. The oil passes through a screen filter in the inlet oil port of the governor before entering passages in the governor. The passages direct oil to output shaft (9) and to the rear of riser shaft (8). An internal passage and cross-drilled holes in shaft (8) allow lubrication of riser (5), the spring seat assembly, and the transfer pump cam.

Fuel Ratio Control

The turbocharged engine uses a fuel ratio control (FRC) to control smoke during acceleration at low boost levels. The FRC restricts the amount of fuel to the combustion chambers until sufficient boost has been achieved.

Governor Linkage And Fuel Ratio Control Schematic
(1) Governor output shaft. (2) Inlet port. (3) Fuel ratio control. (4) Retainer shaft. (5) FRC lever. (6) Limit lever setscrew. (7) FRC lever setscrew. (8) Limit lever.

Fuel ratio control (3) operates on boost air pressure delivered by a tube between inlet port (2) and the engine's inlet manifold. At low boost, retainer shaft (4) is held stationary by springs inside the FRC. When the operator demands more fuel, governor output shaft (1) moves in the FUEL ON direction until limit lever (8) contacts setscrew (7) of FRC lever (5). With FRC lever (5) restrained from FUEL ON (CW) movement by the FRC, further FUEL ON movement of governor output shaft (1) is stopped. Thus, overfueling is prevented.

As engine power increases, boost pressure also increases. This pressure acts against a diaphragm inside the FRC. When boost is sufficient, spring force inside the FRC is overcome and retainer shaft (4) moves to the right. Now FRC lever (5) and limit lever (8) can rotate CW, allowing governor output shaft (1) to move in the FUEL ON direction until limit lever (8) contacts limit lever setscrew (6).

When boost pressure decreases, springs inside fuel ratio control (3) return retainer shaft (4) to normal position. FUEL ON movement of governor output shaft (1) is again restricted.

Governor Servo

The governor servo gives hydraulic assistance to the mechanical governor force moving the governor output shaft on engines with close regulation requirements. The servo equipped governor will have 2 flyweights.

Governor Servo (Fuel On Direction)
(1) Valve. (2) Piston. (3) Cylinder. (4) Cylinder sleeve. (5) Clevis for fuel injector rack control linkage. (A) Oil inlet (shown out of position). (B) Oil outlet. (C) Oil passage. (D) Oil passage.

The components of the governor servo are cylinder (3) (part of governor rear housing), cylinder sleeve (4), piston (2) and valve (1). When the governor moves in the FUEL ON direction, valve (1) moves to the left. The valve opens oil outlet (B) and closes oil passage (D). Pressure oil from oil inlet (A) pushes piston (2) and clevis (5) to the left. Oil behind the piston goes through oil passage (C), along valve (1) and out oil outlet (B).

Governor Servo (Balanced Position)
(1) Valve. (2) Piston. (3) Cylinder. (4) Cylinder sleeve. (5) Clevis for fuel injector rack control linkage. (A) Oil inlet (shown out of position). (B) Oil outlet. (C) Oil passage. (D) Oil passage.

When the governor spring and flyweight forces are balanced and the engine speed is constant, valve (1) stops moving. Pressure oil from oil inlet (A) pushes piston (2) until oil passage (D) is opened. Oil now flows through oil passage (D) along valve (1) and out through oil outlet (B). With no oil pressure on the piston, the piston and clevis (5) stop moving.

Governor Servo (Fuel Off Direction)
(1) Valve. (2) Piston. (3) Cylinder. (4) Cylinder sleeve. (5) Clevis for fuel injector rack control linkage. (A) Oil inlet (shown out of position). (B) Oil outlet. (C) Oil passage. (D) Oil passage.

When the governor moves in the FUEL OFF direction, valve (1) moves to the right. The valve closes oil outlet (B) and opens oil passage (D). Pressure oil from oil inlet (A) is now on both sides of piston (2). The area of the piston is greater on the left side than on the right side of the piston. The force of the oil is also greater on the left side of the piston and moves the piston and clevis (5) to the right.

Dashpot

Dashpot
(1) Spring seat. (2) Dashpot spring. (3) Piston. (4) Seat. (5) Overflow passage. (6) Orifice plug. (7) Oil passage. (8) Reservoir. (9) Passage.

Governors on engines requiring close regulation are equipped with a dashpot. The dashpot improves engine stability during sudden load changes.

Engine oil is supplied to the dashpot by small passage (7) near the end of the riser shaft. Oil then flows through passage (9) to fill reservoir (8). Excess oil leaves the reservoir through overflow passage (5).

When spring seat (1) is moved by a change in load or speed, dashpot spring (2) moves piston (3) in seat (4). During a speed increase or load decrease, piston (3) moves to the right. The oil in the piston cavity is put under pressure as the oil is forced through a small orifice in plug (6) and into reservoir (8).

When engine speed decreases, piston (3) moves to the left causing a pressure decrease in the piston cavity. Oil is now pulled through orifice plug (6) from reservoir (8).

Orifice plug (6) restricts the oil flow to and from the piston cavity. This orifice causes a restriction to movement of piston (3) and spring seat (1). The faster the governor tries to move spring seat (1), the greater resistance the dashpot gives to the spring seat movement.

Fuel Shutoff Solenoid

Fuel Shutoff Solenoid (Energize To Run)
(1) Solenoid.

The fuel shutoff mechanism is activated by an energize to run solenoid. A spring loaded plunger inside the solenoid acts on a lever assembly within the front housing of the governor. This lever assembly pushes the governor output shaft to FUEL OFF position when the plunger of the solenoid is released at engine shutdown. At startup, when the solenoid is energized the plunger moves to the run position. The governor output shaft is then free to move to the FUEL ON position.

Typical Example
Fuel Shutoff Solenoid (ETR) Wiring Diagram
(1) Fuel shutoff solenoid. (2) Ignition switch. (3) Fuse. (4) Magnetic switch. (5) Circuit breaker. (6) Magnetic switch. (7) Circuit breaker. (8) Alternator. (9) Starter. (10) Battery. (11) Disconnect switch.

Air Inlet And Exhaust System

Air To Air Aftercooler

Air Inlet And Exhaust System Schematic
(1) Inlet manifold. (2) Radiator. (3) Aftercooler. (4) Exhaust manifold. (5) Muffler. (6) Turbocharger turbine wheel. (7) Turbocharger compressor wheel. (8) Air filter.

Air System Components
(1) Inlet manifold. (4) Exhaust manifold. (9) Magnetic switch. (10) Inlet air heater. (11) Inlet (to inlet manifold). (12) Turbocharger outlet (to aftercooler). (13) Turbocharger inlet (from air filter). (14) Turbocharger outlet (to exhaust). (15) Turbocharger.

The components of the air inlet and exhaust system control the quality and amount of air available for combustion. These components are the air filter, turbocharger, aftercooler, cylinder head, valves and valve system components, pistons and cylinders, inlet air heater, inlet manifold, and the exhaust manifold.

The air inlet and exhaust system incorporates an air to air aftercooler. Cooling of the inlet air increases combustion efficiency, which helps to lower fuel consumption and increase horsepower output. To improve the combustion process and performance, a separate air cooler core is installed in front of the engine radiator core of the truck. Ambient temperature air is moved across both cores by the engine fan and by the ram effect of the vehicles forward motion, This cools the turbocharger inlet air and the engine coolant.

Inlet air is pulled through the air cleaner, compressed and heated by the turbocharger to about 150°C (300°F), then pushed through the air to air aftercooler core and moved to the air inlet manifold at about 43°C (110°F).

Clean air from the air cleaner is pulled into turbocharger inlet (13) by turbocharger compressor wheel (7). The rotation of the turbocharger compressor wheel compresses the air and forces it through aftercooler (3). Ambient temperature air is moved across the aftercooler to lower the inlet air temperature to approximately 43°C (110°F) before it goes into the inlet manifold. The compressed air flows through the inlet manifold to fill the inlet chambers in the cylinder head. Cooling of the inlet air increases combustion efficiency, which helps to lower fuel consumption and increase horsepower output.

Air flow from the inlet chambers into the cylinders is controlled by the intake valves. There is one intake and one exhaust valve for each cylinder. Make reference to Valve System Components. The intake valve opens when the piston moves down on the inlet stroke. Compressed air from the inlet chamber is pulled into the cylinder.

The intake valve closes and the piston starts to move up on the compression stroke. When the piston is near the top of the compression stroke, fuel is injected into the cylinder. The fuel mixes with the air and combustion starts. The force of combustion pushes the piston down on the power stroke. When the piston moves up again it is on the exhaust stroke. The exhaust valve opens and the exhaust gases are pushed through the exhaust port into exhaust manifold (4). After the piston makes the exhaust stroke, the exhaust valve closes and the cycle (inlet, compression, power, exhaust) starts again.

Exhaust gases from the exhaust manifold go into the turbine side of the turbocharger (15) and cause turbine wheel (6) to turn. The turbine wheel is connected to the shaft that drives compressor wheel (7). The exhaust gases then go out the exhaust outlet (14).

Turbocharger

Turbocharger Cross Section
(1) Exhaust inlet. (2) Turbine wheel. (3) Oil inlet port. (4) Compressor wheel. (5) Air inlet. (6) Bearings. (7) Oil outlet port.

The turbocharger is mounted to the exhaust manifold of the engine. All the exhaust gases go through the turbocharger. The exhaust gases go into exhaust inlet (1) of the turbine housing and push the blades of turbine wheel (2). This causes the turbine wheel and compressor wheel to turn at speeds up to 100 000 rpm.

Clean air from the air cleaner is pulled through the compressor housing air inlet (5) by rotation of compressor wheel (4). The action of the compressor wheel blades causes a compression and heating of the inlet air. The hot compressed air from the turbocharger is then cooled by the air-to-air aftercooler before going to the inlet manifold of the engine. This compressin gives the engine more power because it makes it possible for the engine to burn additional fuel with greater efficiency.

Maximum rpm of the turbocharger is controlled by the fuel setting, the high idle rpm setting and the height above sea level at which the engine is operated.

Turbocharger Oil Lines
(8) Oil inlet line. (9) Oil drain line.

The bearings (6) in the turbocharger use engine oil under pressure for lubrication. The oil is sent through oil inlet line (8) to inlet port (3) at the top, then goes through passages in the center section for lubrication of the bearings. Then the oil goes out oil outlet port (7) at the bottom and back to the engine block through drain line (9).

Valve System Components

Valve System Components
(1) Valve. (2) Spring. (3) Rocker arm. (4) Push rod. (5) Lifter. (6) Camshaft lobe.

The valve system components control the flow of inlet air and exhaust gases into and out of the cylinders during engine operation.

The crankshaft gear drives the camshaft gear through an idler. The camshaft must be timed to the crankshaft to get the correct relation between piston and valve movement.

The camshafts have three cam lobes for each cylinder. Two lobes operate the valves (one intake and one exhaust) and one operates the fuel injector. As the camshaft turns, lobes (6) on the camshaft cause the lifters (5) to move push rods (4) up and down. Upward movement of the push rods against rocker arms (3) results in downward movement (opening) of valves (1).

Each cylinder has one intake and one exhaust valve. Valve springs (2) close the valves when the lifters move down.

Inlet Air Heater

To aid starting and prevent white smoke emission at start up, the Caterpillar 3116 Truck Engines are equipped with an electric heater located at the air inlet casting. The heater control module is mounted on the rear left side of the cylinder head and senses engine oil pressure, engine coolant temperature, and time. Under the proper conditions, the control module activates a magnetic switch (relay) located on the inlet manifold cover, which turns the heater on and off.

Inlet Air Heater Operation

The inlet air heater is used to warm the air for combustion as a starting aid, and to help eliminate excessive engine smoking (white smoke) during startup and improve cold weather startability. The inlet air heater system is designed to provide heat prior to start up, during cranking, and after the engine has started. The control module has a built in circuit board which allows the heater to stay on for thirty seconds for pre-heating when the ignition switch is turned to the "RUN" position. It also provides heat during cranking and for a maximum of seven minutes during the regular heating cycle after the engine is operating. The inlet air heater will be on only until the engine approaches the normal operating temperature.

An indicator lamp will illuminate for two seconds every time the ignition switch is placed in the "RUN" position for a lamp test. The lamp will also be illuminated whenever power is supplied to the heater.

If for any reason the inlet air heater system malfunctions, the engine will still start and run. The only concerns may be the amount of "white smoke" present and the possible need to use an alternative starting aid.

Location Of Components
(1) Inlet manifold. (2) Atomizer. (3) Magnetic switch. (4) Inlet air heater. (5) Air inlet elbow. (6) Ground strap (from heater group to the engine).

Location Of Components
(7) Water temperature regulator housing. (8) Water temperature switch.

Location Of Components
(9) Heater control module. (10) Oil manifold. (11) Oil pressure switch.

The basic components of the inlet air heater system are: magnetic switch, heater control module, heater element, a water temperature switch, and an oil pressure switch.

The inlet air heater (4) is located in inlet manifold (1). The inlet air heater has a ground strap (6) that must be connected to the engine. A gasket is used on each side of the inlet air heater.

The heater control module (9) is mounted on the left hand side of the engine. The heater control module requires input from oil pressure switch (11) and water temperature switch (8) to control the heating cycle of the heater element.

The water temperature switch (8) is located in the water temperature regulator housing (7) and monitors the coolant temperature. When the coolant temperature is BELOW 18.3 ± 2.7 °C (65 ± 5 °F) the coolant sensor will send a signal to the heater control module to turn ON the power to the heater element. When the coolant temperature is ABOVE 29.4 ± 2.7 °C (85 ± 5 °F) the coolant sensor will send a signal to the heater control module to turn OFF the power to the heater element.

The oil pressure switch (11) is located in oil manifold (10). The normally open switch will signal the heater control module to turn ON the power to the heater element when the engine is running and the oil pressure is 240 ± 70 kPa (35 ± 10 psi).

The heater control module uses a built in circuit board to control the heating cycle of the heater element. A magnetic switch (3) is used to turn the 12 volt electrical resistance heater on and off. Once the engine has reached both normal engine oil pressure, and jacket water temperature, the heater control module breaks the current to the magnetic switch which shuts off the current to the heater element.

With the ignition switch turned to the "RUN" position, the inlet air heater will be turned on (pre-heat) for a maximum of thirty seconds before the ignition is turned to the "START" position. When the engine begins to crank, a sixty second timer is started. If the engine does not start within the sixty second period, the heater control module will remove power to the heater element. The regular heat cycle will be off until the ignition is turned to the "OFF" position (this will reset the heater control module and start the sixty second timer each time the engine begins a cranking cycle). The heater control module will allow the heater element to be on a maximum of seven minutes during the regular heating cycle after the engine is running.

Lamp Test

When the ignition switch is turned to the "RUN" position, the control module energizes the magnetic switch, supplying the heater element with power for two seconds. The indicator lamp in the instrument panel should illuminate at that time. Failure of the lamp to illuminate indicates a system malfunction. The lamp will also be illuminated whenever power is supplied to the heater.

NOTE: If the coolant temperature is below 18.3 ± 2.7 °C (65 ± 5 °F), the system should go directly from the lamp test into the pre-heat cycle (light will not turn off).

Pre-Heat Cycle

Three conditions must exist before the inlet air heater will operate in the pre-heat cycle:

1. The ignition switch must be in the "RUN" position.

2. The coolant temperature is below 18.3 ± 2.7 °C (65 ± 5 °F).

3. The inlet air heater has not timed out for thirty seconds in the pre-heat cycle.

When the above conditions exist, the heater control module is programmed to engage the magnetic switch, and supply power to the heater element. The heater element will be ON a maximum of thirty seconds before the ignition switch is moved to the "START" position.

There are three ways to end the pre-heat cycle:

1. The ignition switch is turned to the "START" position. When the switch is turned to the "START" position, the pre-heat cycle is terminated. After the engine starts, and the ignition switch is returned to the "RUN" position, engine oil pressure is above 240 ± 70 kPa (35 ± 10 psi), and the coolant temperature is below 29.4 ± 2.7 °C (85 ± 5 °F) the inlet air heater will operate in the regular heat cycle up to seven minutes.

2. The ignition switch is turned to the "OFF" position.

3. The engine coolant temperature is ABOVE 29.4 ± 2.7 °C (85 ± 5 °F).

Regular Heat Cycle

Four conditions must exist before the inlet air heater will operate in the regular heat cycle:

1. The ignition switch must be in the "RUN" position with the engine running.

2. The coolant temperature is below 29.4 ± 2.7 °C (85 ± 5 °F).

3. The engine oil pressure is above 240 ± 70 kPa (35 ± 10 psi).

4. The inlet air heater has not timed out for seven minutes in the regular heat cycle.

When the above conditions exist, the heater control module is programmed to engage the magnetic switch, and supply power to the heater element. The heater element will be ON a maximum of seven minutes.

There are four ways to end the regular heat cycle:

1. The ignition switch is turned to the "OFF" position. When the switch is turned to the "OFF" position, the regular heat cycle is terminated.

2. If the engine does not start within the sixty second period, the heater control module will remove power to the heater element. The regular heat cycle will be off until the ignition is turned to the "START" position (this will reset the heater control module).

3. The engine coolant temperature is ABOVE 29.4 ± 2.7 °C (85 ± 5 °F). When the coolant reaches this temperature, the coolant sensor opens and and signals the heater control module to remove power to the heater element. The regular heat cycle will be off as long as the coolant temperature is above 29.4 ± 2.7 °C (85 ± 5 °F).

4. The system reaches its seven minute time limit. The heater control module limits the length of time the heater is on to seven minutes. The system will remain disabled until the ignition switch is turned to the "OFF" position.

Typical System Schematic

Inlet Air Heater Controller Functional Flow Chart

Ether Start Aid

Location Of Atomizer
(1) Air inlet manifold. (2) Atomizer. (3) Heater Group. (4) Air Inlet Elbow.

Show/hide table

When using starting fluid, follow the manufacturer's instructions carefully. Use ether sparingly and spray it only while cranking the engine. Also, do not store starting fluid in the cab. Failure to store properly, could result in an explosion and/or fire and possible personal injury.

Ether can be used to aid in cold weather startability. Ether is injected into the center port of the air inlet manifold (1). The Atomizer (2) has two ports (180° apart) that must be aimed parallel to the length of the block. If the atomizer is not located in the air inlet manifold correctly, ether could be directed onto the inlet air heater. Possible extensive damage to the engine could occur if ether is directed at the heater element while the inlet air heater is activated.

Lubrication System

Lubrication System Schematic
(1) Governor oil supply line. (2) To rocker arms. (3) Cylinder head gallery. (4) To push rod lifters mounted in the side covers. (5) Camshaft bearing. (6) Main oil gallery. (7) Passage in front housing. (8) To camshaft idler bearing. (9) To oil pump idler gear bearing. (10) Passage. (11) Piston cooling jets. (12) Main bearings. (13) Turbocharger oil supply line. (14) Oil filter bypass valve. (15) Oil cooler bypass valve. (16) Oil filter. (17) Oil cooler. (18) Oil pan. (19) Oil pump. (A) Auxillary oil filter (if equipped).

Oil pump (19) is mounted to the bottom of the cylinder block inside the oil pan. The pump pulls oil from oil pan (18) and pushes the oil through passage (10) to oil cooler (17). Oil then flows through oil filter (16). The filtered oil then enters the turbocharger oil supply line (13) and main oil gallery (6).

NOTE: Engines equipped with an auxillary oil filter (A) will pick up oil at port (B) on oil cooler (17) and the filtered oil will be returned to the oil pan (18).

Engine - Right Side
(13) Turbocharger oil supply line. (14) Oil filter bypass valve. (15) Oil cooler bypass valve. (16) Oil filter. (17) Oil cooler. (20) Turbocharger oil return line. (B) Port for auxillary oil filter (if equipped).

Engine - Left Side
(1) Governor oil supply line. (21) Crankcase breather. (22) Location of oil passage for push rod lifters (inside each side cover).

The main oil gallery distributes oil to main bearings (12), piston cooling jets (11) and camshaft bearings (5). Oil from gallery (6) also exits the front of the block and enters passage (7) cast in the front housing.

Front housing passage (7) sends the oil flow in two directions. At the upper end of passage (7), oil is directed back into the block and up to cylinder head oil gallery (3). At the lower end of passage (7), oil enters passage (9). This passage sends oil to the oil pump housing to lubricate the oil pump idler gear.

Oil from the front main bearing enters passage (8) to lubricate the camshaft idler gear bearing. Oil passages in the crankshaft send oil from all the main bearings to the connecting rod bearings.

Passages (4) send oil from the camshaft bearings to an oil passage (22) in the side covers. The oil then enters a hole in the shafts of the push rod lifters to lubricate the lifter roller bearings.

Cylinder head oil gallery (3) provides flow to governor oil supply line (1) and rocker arm supports. Holes in the rocker arm supports allow lubrication of valve and injector components.

After the lubrication oil has done its work, it goes back to the engine oil pan.

There is a bypass valve in the oil pump. This bypass valve controls the pressure of the oil coming from the oil pump. The oil pump can put more oil into the system than is needed. When there is more oil than needed, the oil pressure increases and the bypass valve will open. This allows the oil that is not needed to go back to the suction side of the oil pump.

With the engine cold (starting conditions), bypass valves (14 and 15) will open and give immediate lubrication to all components when cold oil with high viscosity causes a restriction to the oil flow through oil cooler (17) and oil filter (16). The oil pump sends the cold oil through the bypass valves around the oil cooler and oil filter to the turbo supply line and the main oil gallery in the cylinder block.

When the oil gets warm, the pressure difference in the bypass valves decreases and the bypass valves close. Now there is a normal flow of oil through the oil cooler and oil filter.

The bypass valves will also open when there is a restriction in the oil cooler or oil filter. This action does not let an oil cooler or oil filter with a restriction prevent lubrication of the engine.

Crankcase breather (21) allows blow-by gases from the cylinders to escape from the crankcase. This prevents pressure from building up that could cause seals and gaskets to leak.

Cooling System

This engine has a pressure type cooling system with a shunt line.

A pressure type cooling system gives two advantages. The first advantage is that the cooling system can have a safe operation at a temperature that is higher than the normal boiling (steam) point of water. The second advantage is that this type of system prevents cavitation (the sudden making of low pressure bubbles in liquids by mechanical forces) in the water pump. With a pressure system, it is more difficult for an air or steam pocket to be made in the cooling system.

The shunt line keeps the water pump from cavitation, by providing a constant flow of coolant to the water pump.

NOTE: In air to air aftercooled systems, a coolant mixture with a minimum of 30% ethylene glycol base antifreeze must be used for efficient water pump performance. This mixture keeps the cavitation temperature range of the coolant high enough for efficient performance. Dowtherm 209 antifreeze can not be used because it does not raise the water pump cavitation temperature of the coolant high enough.

Cooling System Schematic
(1) Cylinder head. (2) Water temperature regulator housing. (3) Expansion tank. (4) Shunt line (expansion tank to water pump). (5) Bypass hose. (6) Radiator. (7) Cylinder block. (8) Oil cooler. (9) Water pump.

Water pump (9) is located on the right side of the cylinder block. It is belt driven from the crankshaft pulley. Coolant can enter the water pump three ways: through the bottom inlet of the water pump, through bypass hose (5) into the top of the water pump, or through shunt line (4) into the top of the water pump.

Coolant from the bottom of the radiator is pulled into the bottom inlet of the pump by impeller rotation. The coolant exits the back of the pump directly into the oil cooler cavity of the block.

All the coolant passes through the core of the oil cooler and enters the internal water manifold of the cylinder block. The manifold distributes the coolant to water jackets around the cylinder walls.

Water Lines Group
(1) Cylinder head. (2) Water temperature regulator housing. (5) Bypass hose. (9) Water pump. (10) Outlet (to radiator). (11) Water temperature regulator. (12) Water return from air compressor (if equipped). (13) Air vent valve. (14) Heater supply and return ports (located on the back side of housing). (15) Water supply to air compressor (if equpped). (16) Shunt connector. (A) Port for pump outlet pressure (for engine diagnosis).

From the cylinder block, the coolant flows into passages in the cylinder head. The passages send the flow around the unit injector sleeves and inlet and exhaust passages. The coolant now enters water temperature regulator housing (2) at the front right side of the cylinder head.

Water temperature regulator (11) controls the direction of flow. If the coolant temperature is less than normal, the water temperature regulator is closed. The coolant is directed through bypass hose (5) and into the top inlet of the water pump. When the coolant gets to the correct temperature, water temperature regulator (11) opens, and closes the bypass going to the pump. Most of the coolant goes through outlet (10) to the radiator for cooling. The remainder flows through bypass hose (5) and into the water pump.

The shunt line (4) runs from the top of the water pump to an expansion tank. This line must be routed to avoid trapping any air. By providing a constant flow of coolant available to the water pump, the shunt line keeps the water pump from cavitation.

NOTE: Water temperature regulator (11) is an important part of the cooling system. It divides coolant flow between the radiator and the bypass as necessary to maintain the correct temperature. If the water temperature regulator is not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operating temperatures.

NOTE: Air vent valve (13) will allow the air to escape past the water temperature regulator from the cooling system while the radiator is being filled. During normal operation the air vent valve will be closed to prevent any coolant flow past the water temperature regulator.

Coolant For Air Compressor (If Equipped)

Coolant Lines For Air Compressor
(17) Coolant supply line (18) Coolant return line (19) Air compressor.

If the engine is equipped with an air compressor, coolant is supplied from the water temperature regulator housing to air compressor (19) through line (17) and is circulated through the air compressor and is returned to the cooling system through line (18) into the water temperature regulator housing (2).

Coolant Conditioner (If Equipped)

Some conditions of operation have been found to cause pitting (small holes in the metal surface) from corrosion or cavitation erosion (wear caused by air bubbles in the coolant) on the outer surface of the cylinder wall and the inner surface of the cylinder block next to the cylinder wall. The addition of a corrosion inhibitor (a chemical that gives a reduction of pitting) can keep this type of damage to a minimum.

The "spin-on" coolant conditioner element, similar to the fuel filter and oil filter elements, fastens to a base that is mounted on the front of the engine. Coolant flows from the water pump through the base and element back to the block. There is a constant flow of coolant through the element when valves are in the OPEN position.

The element has a specific amount of inhibitor for acceptable cooling system protection. As coolant flows through the element, the corrosion inhibitor, which is a dry material, dissolves (goes into solution) and mixes to the correct concentration. Two basic types of elements are used for the cooling system, and they are called the "PRECHARGE" and the "MAINTENANCE" elements. Each type of element has a specific use and must be used correctly to get the necessary concentration for cooling system protection. The elements also contain a filter and should be left in the system so coolant flows through it after the conditioner material is dissolved.

The "PRECHARGE" element has more than the normal amount of inhibitor, and is used when a system is first filled with new coolant (unless Dowtherm 209 Antifreeze is used). This element has to add enough inhibitor to bring the complete cooling system up to the correct concentration.

The "MAINTENANCE" elements have a normal amount of inhibitor and are installed at the first change interval and provide enough inhibitor to keep the corrosion protection at an acceptable level. After the first change period, only "MAINTENANCE" elements are installed at specified intervals to give protection to the cooling system.

Basic Block

Cylinder Block And Head

The cylinder block has seven main bearings. Two bolts hold each bearing cap to the block.

Removal of the oil pan allows access to the crankshaft, main bearings caps, piston cooling jets, and oil pump.

The camshaft compartment is accessible through covers on the left side of the cylinder block. These side covers support the push rod lifters. The camshaft is supported by bearings pressed into the cylinder block. There are seven camshaft bearings.

The cylinder head is separated from the block by a steel and non-asbestos fiber gasket. Coolant flows out of the block through gasket openings and into the head. This gasket also seals the oil supply and drain passages between the block and the head. The air inlet ports are on the top of the head, while the exhaust ports are located on the right side of the head. There is one intake and one exhaust valve for each cylinder. Replaceable valve guides are pressed into the cylinder head. The fuel injector is located between the two valves. Fuel is injected directly into the cylinders at very high pressure. A push rod and rocker arm system controls the valves and fuel injectors.

Pistons, Rings And Connecting Rods

One piece aluminum pistons are used in the lower horsepower (kW) applications of the 3116 engines. High output engines with high cylinder pressures require two piece articulated pistons. Refer to the parts book to obtain information about the type of pistons used in a specific engine.

The aluminum one piece piston has three rings: two compression rings and one oil ring. All the rings are located above the piston pin bore. The seat for the rings is an iron band that is cast into the piston. The two compression rings are of the KEYSTONE type, which have a tapered shape. The action of the ring in the piston groove, which is also tapered, helps prevent seizure of the rings caused by carbon deposits. The oil ring is a standard (conventional) type. Oil returns to the crankcase through holes in the oil ring groove.

The two piece articulated piston consist of an alloy forged steel crown connected to an aluminum skirt by the piston pin. The two piece articulated piston has three rings: two compression rings and one oil ring. All the rings are located above the piston pin bore. The seat for the rings is an iron band that is cast into the piston. The two compression rings are of the KEYSTONE type, which have a tapered shape. The action of the ring in the piston groove, which is also tapered, helps prevent seizure of the rings caused by carbon deposits. The oil ring is a standard (conventional) type. Oil returns to the crankcase through holes in the oil ring groove.

Oil from the piston cooling jets spray the underside of the pistons. This lubricates and cools the pistons, and improves piston and ring life.

The connecting rod has a taper on the pin bore end. This gives the rod and piston more strength in the areas with the most load. Two bolts hold the rod cap to the rod. This design keeps the rod width to a minimum, so that the rod can be removed through the cylinder.

Crankshaft

The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the equipment. A vibration damper is used at the front of the crankshaft to reduce torsional vibrations (twist on the crankshaft) that can cause damage to the engine.

The crankshaft drives a group of gears on the front of the engine. The gear group drives the oil pump, camshaft, governor, and the gear driven air compressor and/or power steering pump. In addition to this, the front belt pulleys on the crankshaft drive the radiator fan, water pump, alternator and freon compressor.

Hydrodynamic seals are used at both ends of the crankshaft to control oil leakage. The hydrodynamic grooves in the seal lip move lubrication oil back into the crankcase as the crankshaft turns. The front seal is located in the front housing. The rear seal is installed in the flywheel housing.

Pressure oil is supplied to all main bearings through drilled holes in the webs of the cylinder block. The oil then flows through drilled holes in the crankshaft to provide oil to the connecting rod bearings. The crankshaft is held in place by seven main bearings. A thrust main bearing next to the rear main bearing controls the end play of the crankshaft.

Vibration Damper

The force from combustion in the cylinders will cause the crankshaft to twist. This is called torsional vibration. If the vibration is too great, the crankshaft will be damaged. The vibration damper limits the torsional vibrations to an acceptable amount to prevent damage to the crankshaft.

The vibration damper is installed on the front of crankshaft (1). The damper has a weight (2) in a case (3). The space between the weight and the case is filled with thick fluid. The weight moves in the case to limit the torsional vibration.

Cross Section Of Vibration Damper
(1) Crankshaft. (2) Weight. (3) Case.

Camshaft

The camshaft is located in the upper left side of the block. The camshaft is driven by gears at the front of the engine. Seven bearings support the camshaft. A thrust plate is mounted between the camshaft drive gear and a shoulder of the camshaft to control the end play of the camshaft.

The camshaft is driven by an idler gear which is driven by the crankshaft gear, so the camshaft rotates in the same direction as the crankshaft (CCW as viewed from the flywheel). There are timing marks on the crankshaft gear, idler gear, and the camshaft gear to assure the correct camshaft timing to the crankshaft for proper valve and injector operation.

As the camshaft turns, each lobe moves a lifter assembly. There are three lifter assemblies for each cylinder. Each outside lifter assembly moves a push rod and valve (either intake or exhaust). The center lifter assembly moves a push rod that operates the fuel injector. The camshaft must be in time with the crankshaft. The relation of the cam lobes to the crankshaft position cause the valves and fuel injector in each cylinder to operate at the correct time.

Electrical System

The electrical system can have three separate circuits: the charging circuit, the starting circuit and the low amperage circuit. Some of the electrical system components are used in more than one circuit. The battery (batteries), circuit breaker, ammeter, cables and wires from the battery are all common in each of the circuits.

The charging circuit is in operation when the engine is running. An alternator makes electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output to keep the battery at full charge.

If the vehicle has a disconnect switch, the starting circuit can operate only after the disconnect switch is put in the ON position.

The starting circuit is in operation only when the start switch is activated.

The low amperage circuit and the charging circuit are both connected to the same side of the ammeter. The starting circuit connects to the opposite side of the ammeter.

Charging System Components

Alternator

Alternator Components (Typical Example)
(1) Brush holder. (2) Rear frame. (3) Rotor. (4) Stator. (5) Drive end frame. (6) Fan assembly. (7) Slip rings. (8) Rectifier.

The alternator used on the 3116 Truck Engines has three phase, full-wave, rectified output. It is a brush type alternator.

The alternator is an electrical and mechanical component driven by a belt from engine rotation. It is used to charge the storage battery during engine operation. The alternator is cooled by a fan that is a part of the alternator. The fan pulls air through holes in the back of the alternator. The air exists the front of the alternator, cooling it in the process.

The alternator converts mechanical and magnetic energy to alternating current (AC) and voltage. This process is done by rotating a direct current (DC) electromagnetic field (rotor) inside a three phase stator. The alternating current and voltage (generated by the stator) are changed to direct current by a three phase, full wave rectifier system using six silicone rectifier diodes. The alternator also has a diode trio which is an assembly made up of three exciter diodes. The diode trio rectifies field current needed to start the charging process. Direct current flows to the alternator output terminal.

A solid state regulator is installed in the back of the alternator. Two brushes conduct current, through two slip rings, to the field coil on the rotor.

There is also a capicitor mounted in the back of the alternator. The capacitor protects the rectifier from high voltages. It also suppresses radio noise.

Regulator

The voltage regulator is a solid state (transistor, stationary parts) electronic switch which controls the alternator output. The regulator limits the alternator voltage to a preset value by controlling the field current. It feels the voltage in the system and switches "ON" and "OFF" many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output.

NOTE: Refer to Service Manual, Form No. SENR3862, for detailed service information for the Delco Remy 21 SI Series Alternator.

NOTE: For engines which have the alternator connected to an engine component, the ground strap must connect that component to the frame or to the battery ground.

Starting System Components

Starter Solenoid

A solenoid is a magnetic switch that does two basic operations:

1. Closes the high current starter motor circuit with a low current start switch circuit.

2. Engages the starter motor pinion with the ring gear.

Typical Solenoid

The solenoid switch is made of an electromagnet (one or two sets of windings) around a hollow cylinder. There is a plunger (core) with a spring load inside the cylinder that can move forward and backward. When the start switch is closed and electricity is sent through the windings, a magnetic field is made that pulls the plunger forward in the cylinder. This moves the shift lever (connected to the rear of the plunger) to engage the pinion drive gear with the ring gear. The front end of the plunger then makes contact across the battery and motor terminals of the solenoid, and the starter motor begins to turn the flywheel of the engine.

When the start switch is opened, current no longer flows through the windings. The spring now pushes the plunger back to the original position, and, at the same time, moves the pinion gear away from the flywheel.

When two sets of windings in the solenoid are used, they are called the hold-in winding and the pull-in winding. Both have the same number of turns around the cylinder, but the pull-in winding uses a larger diameter wire to produce a greater magnetic field. When the start switch is closed, part of the current flows from the battery through the hold-in windings, and the rest flows through the pull-in windings to motor terminal, then through the motor to ground. When the solenoid is fully activated (connection across battery and motor terminal is complete), current is shut off through the pull-in windings. Now only the smaller hold-in windings are in operation for the extended period of time it takes to start the engine. The solenoid will now take less current from the battery, and heat made by the solenoid will be kept at an acceptable level.

Starter Motor

Starter Motor (Typical Example)
(1) Brush assembly. (2) Field. (3) Solenoid. (4) Clutch. (5) Pinion. (6) Armature.

The starter motor is used to turn the engine flywheel fast enough to get the engine to start running.

NOTE: Some starters have starter-to-frame ground straps. But, many of these starters are not electrically grounded to the engine. They have electrical insulation systems. For this reason, the starter-to-frame ground strap may not be an acceptable engine ground. Original equipment starters are electrically grounded to the engine. They have a ground wire from the starter to the negative terminal of the battery. If a starter change is made, consult an authorized dealer for proper qrounding procedures for that starter.

The starter motor has a solenoid. When the ignition switch is turned to the START position, the starter solenoid will be activated electrically. The solenoid plunger (core) will now move to push the starter pinion, by a mechanical linkage, to engage with the flywheel ring gear. The starter pinion will engage with the ring gear before the electric contacts in the solenoid close the circuit between the battery and the starter motor. When the circuit between the battery and the starter motor is complete, the pinion will turn the engine flywheel. A clutch gives protection for the starter motor so tha the engine cannot turn the starter motor too fast.

When the ignition switch is released from the START position, the starter solenoid is deactivated (current no longer flows through the windings). The spring now pushes the plunger (core) back to the original position, and, at the same time, moves the pinion gear away from the flywheel ring gear.

Other Components

Circuit Breaker

The circuit breaker is a switch that opens the battery circuit if the current in the electrical system goes higher than the rating of the circuit breaker.

A heat activated metal disc with a contact point completes the electric circuit through the circuit breaker. If the current in the electrical system gets too high, it causes the metal disc to get hot. This heat causes a distortion of metal disc which opens the contacts and breaks the circuit. A circuit breaker that is open can be reset after it cools. Push the reset button to close the contacts and reset the circuit breaker.

Circuit Breaker Schematic
(1) Reset button. (2) Disc in open position. (3) Contacts. (4) Disc. (5) Battery circuit terminals.

Magnetic Pickup

Schematic of Magnetic Pickup

The magnetic pickup is a single pole, permanent magnet generator made of wire coils around a permanent magnet pole piece. As the teeth of the flywheel ring gear go through the magnetic lines of force around the pickup, an AC voltage is made. The ratio between the frequency at this voltage and the speed of the engine is directly proportional.

Magnetic Switch

A magnetic switch (relay) is used for the starter solenoid circuit. Its operation electrically, is the same as the solenoid. Its function is to reduce the low current load on the start switch and control low current to the starter solenoid.

A magnetic switch is used for the inlet air heater circuit. Its function is to control the current to the heater element. Its operation electrically, is the same as a solenoid.

Wiring Diagram

Typical Example 12 Volt Starting System
(1) Ammeter. (2) Lights. (3) Switch (ignition). (4) Gauges. (5) Fuel shutoff solenoid (ETR). (6) Alternator. (7) Starter motor. (8) Magnetic switch (start relay). (9) Heater telltale lamp (OEM supplied). (10) Magnetic switch (power relay). (11) Inlet air heater. (12) Battery. (13) Oil pressure switch. (14) Heater control module. (15) Water temperature switch.