S4Q2 Diesel EngineService Manual # 99719-77100

The following modules do not cover all of the material in the manual. We have identified and chosen some of the more important key points. To fully understand the engine in more depth you will need to read the manual. More hands on work with the lift truck, and real life work will improve your overall knowledge of this equipment.

External View (Left Side)

External View (Right Side)

Serial Number LocationS

Engine Main Parts

Cylinder Heads & Valve MechanismRocker coverAdjusting screwBolt (short)Bolt (long)Valve capSnap ringRocker armRocker shaft bracketRocker shaft springRocket shaftValve pushrodCylinder head boltCylinder headValve cottersUpper valve retainerValve springValve (inlet)Valve (exhaust)Valve stern sealCylinder head gasket

Cylinder Heads & Valve Mechanism

Cylinder Head Remove the rocker coverRemoving rocker shaft assembly.Loosen the adjusting screw one turn. Loosen the bolts, long and short, that hold the rocker shaft bracket to the cylinder head. Be sure to loosen the short bolt first.Remove the rocket shaft assembly from the cylinder head.

Cylinder Head Remove the cylinder head bolts.Lift the head off the crankcase.

Cylinder HeadTighten the cylinder head bolts to the specific torque in the sequence shown. Tightening torque:118 5N-m (12.00 0.5kgfm) [87 4 lbfft]

Pistons, Crankshaft & CrankcaseConnecting rod capConnecting rod bearing (lower half)Main bearing capMain bearing (lower half)CrankshaftMain bearing (upper half)Connecting rodConnecting rod bearing (upper half)Snap ringPiston pinPistonNo.1 ringNo. 2 ringOil ringTappetCrankcase

Pistons, Crankshaft & Crankcase

Piston HeadNote the shape of the injection swirl chamber on the top of the piston.

Installing Piston AssemblyMake sure the piston ring end gaps are arranged on the piston, as shown in the illustration.

Timing Gears, Camshaft & Oil PanCrankshaft pulleyCoverTiming gear casePump drive gearPTO idler gearBaffle plateIdler gearOil panOil pumpCamshaftFront end plate

Timing Gears, Camshaft & Oil Pan

Timing Gear TrainThe timing marks of the gears should be aligned as shown when the no. 1 piston is at top dead center on compression stroke.

Inlet and Exhaust System

Inlet and Exhaust

Inlet and ExhaustAir inlet pipeGasketExhaust manifoldInlet manifoldGasketGasket

Cooling System

Coolant Block Diagram

Water Pump & FanGasketGasketGasketPulleyFanCoverWater pump AssySpacerFan belt

Fan Belt TensionUnit: mm (in.)

ItemStandard ValueBelt Tension (crankshaft pulley alternator pulley)Approx. 13 (0.5118)(when pressed with force of 98 N (10 kgf) [22 lbf])

Fuel SystemZEXEL VE Type Injection Pump

Fuel System Diagram

Fuel Injection pumpDistribution VE-type fuel injection pump.Uses a single high pressure pumping plunger to accurately meter and distribute fuel to each of the engine cylinders.Smaller and lighter than its In-line counterpart.

Comparison of Dimension Size

Cross-section of VE Pump

Sectional View of VE Pump

Fuel Injection Pump

VE Feed PumpThe rotary-vane type feed pump draws fuel from the fuel tank.Feed pump rotor is driven by the pump drive shaft which is connected to the injection pump gear.As the rotor spins, centrifugal force holds the van against the pressure chamber wall.Due to the off-center, fuel becomes trapped between the vane and is pressurized and force out through the delivery port.

VE Pressure Regulating ValveThe pressure regulating valve is located in the upper portion of the injection pump housing.Fuel pressure is proportional to pump speed.As fuel pressure increases with pump speed, the piston within the pressure regulator is forced against the tension of the regulator spring.At a predetermined value, the valve will begin to open a port in the regulator to allow excess fuel to bypass back to the intake port.

Feed Pump Pressure Vs Speed

Plunger and CamplateThe face cam is driven by drive shaft and its rides on the rollers.The distributor plunger and face cam are held against the roller by the plunger spring.As the face cam & plunger rotate, they reciprocate back and forth, delivers high pressure fuel to each cylinder.

Plunger Delivery to Each Nozzle

Intake StrokeFuel from feed pump fills the pressure chamber of the head as the plunger moves toward the drive end of the pump and rotates to align the plunger intake port with the fill port in the distributor head.

Injection StrokeAs the plunger rotates, the intake port is closed and fuel becomes trapped within the pressure chamber.With the continued rotation and now forward motion of the plunger, fuel pressurization and delivery begins.At this point, the outlet port aligns with a distributor passage in the distributor head and injection begins.

End of Injection As a point of forward motion, the spill port of the distributor plunger moves out of the spill ring.Pressure is released and injection is stopped.

Pressure EqualizationAn additional 180o degrees of rotation of the distributor plunger aligns the pressure equalization groove with the distributor passage of the head. This allows the pressure in the distributor passage to equalize to that of the pressure in the pump housing.This pressure equalization minimizes fuel delivery spread between cylinders and allows for a smoother running engine.

Non-ReversingAs illustrated in the figure, if the pump is rotated in the wrong direction, fuel pressurization cannot take place because the fuel intake port is open during cam lift.This non-reversing feature in the pump prevents the engine from running backwards.

Fuel Shut-Off SolenoidTurning the ignition switch to OFF position shuts off the current to the solenoid. With no current to hold the valve, the spring forces the valve to close the fill port.This shut off the fuel supply and the engine stop.

Fuel FilterBracketElement assemblyLevel sensor assemblyPriming pumpDrain plug

Draining Water and SedimentLoosen the drain plug at the bottom of the fuel filter. Operate (push down on) the priming pump of the filter seven times to facilitate draining. After draining, tighten the drain plug.After draining, prime the fuel system.

Priming Filter SidePump the priming button on the fuel feed pump.

Bleeding Air from Fuel FilterLoosen the air vent plug of the fuel filter (by turning it 1.5 turns)

Remove Injection PumpRemove the pipe clamps from the injection pipe.Disconnect the injection pipes at the injection pump and at the injection nozzles.Disconnect the leak-off pipes from the nozzles by loosening the lock nuts.

Remove Injection PumpUsing a box wrench, remove the fuel injection nozzles with gaskets from the engine.Note: remove the nozzle gaskets from the cylinder head, if any, with a wire or a screwdriver and discard them.

Remove Injection PumpCheck the alignment of the mark on the fuel injection pump with mark on the flange plate

Remove Injection PumpRemove the front end cover from the engine.Put marks on the fuel injection pump drive gear and idler.Unscrew the bolts that hold the fuel injection pump flange to the front end plate and remove the pump and flange from the end plate..Note: (1)Do not attemp to run engine after removing the injection pump from the engine. (2)To remove the fuel injection pump drive gear, loosen its nut with the pump on the engine

Lubrication System

Engine oil Lubricating system

Oil Filter500Oil filter

Pressure Relief ValveCheck the valve opening pressure (the oil pressure when engine is running at the rated rpm). If the pressure is not correct, remove the cap bolt and make adjustment by adding or removing shims. The pressure tap (RP 1/8 thread [PS 1/8]) is located near the oil filter.Unit: MPa (kgf/cm2) [psi]

ItemAssembly StandardValve opening pressure0.29 to 0.39(3.0 to 4.0)[43 to 57]

Adjusting Ignition TimingWARNING

Always adjust valves with engine stopped to avoid personal injury. Turn the engine by hand and not by use of the starter. Disconnect the battery.

Adjusting Ignition TimingBring no. 1 cylinder piston to top dead center on compression stroke

Adjusting Ignition TimingConfirm TDC1 by attempting to move the inlet and exhaust rocker arms for no. 1 cylinder

Adjusting Ignition TimingSet the timing to 6 before top dead center

Adjusting Ignition TimingIf the injection timing is retarded, move the injection pump toward the crankcase. If the timing is advanced, move the pump away from the crankcase.

Adjusting Valve Clearance

Governor AdjustmentWarm up engine until coolant and oil temperature rise to 70 oC (158oF) or higher.Low idling setting (no-load minimum rotation speed setting). 700 rpm. Adjust by idling adjust screw.Governor setting (maximum rotation speed setting) 2700 rpm. Adjust by maximum speed adjusting screw.Caution: The idling and maximum speed are preset at factory. Do not adjust unless necessary.

Testing Compression PressureMeasure the compression pressure on all cylindersMeasure the compression pressure with the engine running at 150 to 200 rpm.Unit: MPa (kgf/cm2) [psi]

ItemAssembly StandardRepair LimitCompressure pressure2.94 (30) [427]2.55 (26) [370]

Maintenance Schedule

(c) Attempt to move the inlet and exhaust valve rocker arms for the No. 1 cylinder up and down to make sure they are not being pushed up by their pushrods. With the piston at top dead center on compression stroke, the inlet and exhaust rocker arms are not being pushed up. If these rocker arms are being pushed up, turn the crankshaft once again.(a) Loosen the injection pump mounting nuts.(b) Turn the crankshaft about 30 In reverse direction (counterclockwise as seen from the front side of the engine). Then, turn the crankshaft little by little in normal direction until the correct injection timing mark is aligned with the pointer.(c) Remove the inspection cover from the side of the injection pump.(d) Make sure the flat A of the insert circlip is aligned with the mark E on the drive plate.(e) If the flat A is not aligned with the mark E, move the injection pump to align them.