4M40 DIESEL ENGINE SHOP MANUAL Engine Caterpillar

Specifications

Remarks

Output and torque represent performance of run-in engine operating under the standard ambient conditions and accessories specified below.

Structure And Operation

Exploded View

Cylinder Head and Cylinder Head Gasket

Cylinder head

* The cylinder head has swirl chambers each with a combustion jet that directs the flow of combustion gas from the swirl chamber to the main combustion chamber.

* The combustion jet is held against rotation by a tablet.

* The cylinder head is cooled by coolant flowing through the water jackets formed in it. Water directors are installed at the bottom of the cylinder head to direct coolant flow.

* The intake ports and the exhaust ports are arranged alternately on the right side of the cylinder head (counter-flow type)

* The cylinder head bolts must be tightened according to the specified procedure.

Cylinder head gasket

* Select and use a cylinder head gasket of a thickness that can accommodate the piston projection.

* The size (thickness) class of the gasket can be identified by the shape of the notches cut on the edge of each gasket.

Valve Mechanism and Timing Chain

Valve Mechanism

* The camshaft is driven by the timing chain. Camshaft journals are rotatably held against the cylinder head by camshaft caps.

* A lifter shim is installed between the camshaft and each valve lifter. Valve clearance is adjusted by changing the thickness of the shim.

* The valve springs are unequally pitched springs, each having a paint mark on one end to indicate the top when it is installed.

Timing Chain

* The timing chain is an endless chain with 98 links that connects the cam sprocket and the idler sprocket.

* The timing chain has mark link plates at two locations that indicate the position at which the crankshaft and the camshaft should take when the chain is installed. There are two plates at the first location and one plate at the second location. The first location (two-mark-link location) must be aligned with the mating mark " O " on the cam sprocket and the second location (one-mark-link location) must be aligned with the mating mark " O " on the idler sprocket.

* The guide plate has an oil jet that sprays engine oil on the timing chain through the injection hole.

* The tensioner gives tension to the timing chain. The tensioner has a plunger with a built-in spring.

* When the tensioner is installed in position, the plunger pushes the tension lever and the tension lever, in turn; pushes the chain. The timing chain is tensioned automatically by a force determined by the tension of the plunger spring.

* After the timing chain is adequately tensioned, the plunger is locked in place by a cam provided in the tensioner, which prevents accidental deflection of the timing chain while the engine is running. Do not crank the engine in the reverse direction after installing the tensioner, as this will apply undue forces to the plunger and may cause such undesirable consequences as cam being over ridden by the plunger.

Timing Gears

* Each timing gear has mating mark(s) "1" or "5" on the side of its tooth (teeth) to ensure that it is engaged correctly with another gear during installation. The injection pump gear, however, has a mating mark on the tip of one of its teeth so that alignment of the mark with the mating marks on the flange plate and front plate can be checked from the side of the injection pump.

Idler Gear

* The idler gear is pressed fitted into the idler sprocket, which drives the timing chain, and rotates on the idler shaft.

* The idler shaft is anchored to the crankcase using the idler washer and bolt. The idler sprocket is fitted with the idler bushing, which is lubricated by engine oil supplied through the oil holes drilled in the idler shaft.

Connecting Rods

* The "O" mark is a front mark, which should face in the same direction as the front mark on the piston when the connecting rod and piston are assembled.

* The color mark indicates the diameter class of the big end.

Piston and Piston Rings

* The head of the piston is provided with a front mark that indicates the direction in which the piston is inserted into the crankcase.

* The piston rings are fitted onto the piston with each other's gaps staggered.

Flywheel

* Tooth edges on one side of the ring gear are chamfered for easier engagement with the starter pinion.

Crankcase, Crankshaft and Main Bearings

Crankcase

* The crankcase is a bi-block type consisting of an upper crankcase and a lower crankcase that are assembled to grip the crankshaft in between.

* The upper crankcase has cylinder whose surfaces are machined or direct contact with sliding pistons. The walls of the cylinders have water jackets for cooling the cylinders.

* The main cap bolts that hold the upper crankcase and the lower crankcase together must be tightened according to the specified procedure.

* The upper crankcase is provided with piston size marks based on which position installed must be selected.

Crankshaft

* The crankshaft has two sets of color marks. Color marks A indicate the outside diameter of the journals (at five places), and color marks B indicate the outside diameter of the pins (at four places).

Main Bearing

* Each upper main bearing has an oil hole, which provides a passage for engine oil to the corresponding crankshaft journal.

* Main bearings of different thickness are available so that most appropriate ones can be selected to ensure proper clearance between them and journals. Bearing thickness classes are identified by color marks (black, blue and yellow) painted on the sides of the bearings.

* All the upper and lower bearings are identical except for the No. 3 upper bearing and the No. 3 lower bearing. The No. 3 upper bearing can be distinguished from the No. 3 lower bearing as it has an oil hole.

Thrust Plates

* Two upper and lower thrust plate pairs are installed on both sides of the upper and lower main bearings at the rear most journal of the crankshaft.

* The thrust plates must be of a thickness that corresponds to the end play of the crankshaft. Each thrust plate has two oil grooves to assure its minimum friction against the crankshaft journal.

Oil Seal

Front Oil Seal

* The front oil seal is fitted in the timing gear case, and prevents oil from leaking by contact of its lip with the crankshaft pulley.

Rear Oil Seal

* The rear oil seal is fitted in the rear oil seal case, and prevents oil from leaking by contact of its lip with the crankshaft.

Troubleshooting

General Inspection And Adjustment

Measuring Compression Pressure

Service Standards

* A drop in compression pressure can be used as a guide to determine when the engine should be overhauled.

* Measure the compression pressure at regular intervals. Keeping track of its transitions can provide a useful tool for troubleshooting. On new vehicles and vehicles with newly replaced parts, the compression pressure will be somewhat higher depending on the break-in condition of piston rings, valve seats, etc., but this will return to normal as the parts wear down.

* Before the compression measurement, confirm that the engine oil, starter, and battery are in normal condition.

* Place the vehicle in the following conditions.

* Warm up the engine until the coolant temperature reaches approximately 80 to 90°C.

* Turn off the lights and auxiliaries.

* Place the lever in neutral.

* Remove the connector of the fuel cut solenoid valve to prevent fuel from being injected when the engine is cranked by the starter.

* Remove all glow plugs.

* Cover the glow plug mounting holes with shop towels.

* After cranking the engine by the starter, check that no foreign substances are deposited on the shop towels.

* If there are deposits (such as engine oil or coolant) on the shop towels, the following may be the cause:

* Deposits of engine oil alone can mean a defective piston ring seal; the piston rings must be inspected.

* Deposits of both engine oil and coolant can mean cracks in the cylinders; the crankcase must be replaced.

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* When coolant and engine oil deposits are evident, cranking the engine could be dangerous as these substances, heated to high temperatures, will blow out from the injection nozzle mounting holes. Make sure to stay away from the injection nozzle mounting holes when the engine is being cranked.

* Install a compression gauge adapter (commercially available "TOYO TEC (NPA)", P/N "GN-8" or equivalent) to one of the glow plug mounting holes.

* Crank the engine and measure the compression pressure for all the cylinders one after another. Determine the compression pressure different between the cylinders.

* If the compression pressure is below the limit or the cylinder-to-cylinder pressure differences is not within the limit, pour a small amount of engine oil into the corresponding glow plug mounting hole and remeasure the compression pressure.

* If the compression pressure increases, the piston rings and cylinder surfaces may be badly worn or otherwise damaged.

* If the compression pressure remains unchanged, there may be seizure in the valves, the valves may be incorrectly seated or the cylinder head gasket may be defective.

Inspection and Adjustment of Valve Clearances

Service standards (Unit: mm)

Special tools

* Valve clearances should be checked and adjusted as follows while the engine is still cold.

[Inspection]

* Remove the rocker cover.

* Bring the No. 1 or No. 4 cylinder piston to the top dead center (TDC) on the compression stroke by the following procedure:

* Rotate the crankshaft clockwise so that the notch on the crankshaft pulley is aligned with the "0" mark on the timing gear case.

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* Do not turn the crankshaft pulley in the wrong direction (counterclockwise), as this may cause damage to the tensioner that is adjusting the tension of the timing chain on the idler sprocket and cam sprocket. If you turn the crankshaft pulley in the wrong direction by mistake, remove and reinstall the tensioner.

* This will place either the No. 1 or No. 4 cylinder piston at TDC on the compression stroke. The cylinder with the indentation in the hexagonal portion of the camshaft facing upward has its piston at TDC. Rotate the engine by one full turn to switch the TDCs of the No. 1 and No. 4 cylinder pistons.

* With the No. 1 or No. 4 cylinder piston at TDC, measure the clearance of the valves marked with a circle in the table below.

* The feeler gauge must have a slight drag when taking measurements.

* If the feeler can be moved without any resistance, the measurement will be incorrect.

* If the measurements are not within the standard value range, adjust the valve clearance by the following procedures.

[Adjustment]

* Perform remeasurement for any valves whose clearances are not within the standard value range. Based on these measurements, select a lifter shim of the appropriate thickness that will bring the valve clearance within the standard value range. Thickness of lifter shim to be selected = Thickness of existing shim as measured at cam contact portion + (Clearance measurement - Standard value)

* The thickness of each lifter shim is stamped on its upper surface. Available lifter shim thicknesses: 2.250 mm to 3.150 mm (37 different thicknesses in 0.025 mm increments) Example of thickness indication: "2775" = 2.775 mm thick

* Remove the camshaft. (See later sections.)

* Insert a flat-blade screwdriver into the notch on the valve lifter to remove the lifter shim and replace the lifter shim with one of the appropriate thickness.

* Install the camshaft. (See later sections.)

* Remeasure the valve clearance and check that it is within the standard value range.

Replacement of Timing Chain

Special Tools (Unit: mm)

[Inspection]

* Perform the following inspections.

* Remove the tensioner from the cylinder head and measure the protrusion of the tensioner's plunger (the length from the tip of the plunger to the farthest wear mark). Replace the timing chain if the protrusion exceeds 26 mm.

* Run the engine and check for any abnormal noises that may be created by interference between the piston and the valves. Replace the timing chain if any abnormal noises are detected.

[Replacement]

* Remove the rocker cover and the air suction pipe bracket mounting bolts at the front of the cylinder head. Also remove the brake vacuum pipe if necessary.

*

Install
on the cylinder head and tighten the bolts (M6 x 15 mm) firmly.

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* Tighten the bolts securely to prevent from being thrown off by timing chain's rotation.

* Bring the No. 1 cylinder piston to the top dead center (TDC) on the compression stroke by the following procedure:

* Rotate the crankshaft pulley clockwise so that the notch on the crankshaft pulley is aligned with the "0" mark on the timing gear case.

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* Do not turn the crankshaft pulley in the wrong direction (counterclockwise), as this may cause damage to the tensioner that is adjusting the tension of the timing chain on the idler sprocket and cam sprocket. If you turn the crankshaft pulley in the wrong direction by mistake, remove and reinstall the tensioner.

* The No. 1 cylinder piston is at TDC if either the indentation on the hexagonal portion or the protrusion on the camshaft is facing upward.

* With the No. 1 cylinder piston at TDC, check that the two punch marks on the cam sprocket are at the illustrated positions.

* Crank the engine by hand and bring the mark link plate (one plate) to the illustrated position.

* Remove the tensioner and its gasket from the cylinder head.

* Install
on the cylinder head.

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* Fill the space around the timing chain with shop towels to prevent parts from falling into the timing gear case.

* Using
, remove the pins of the mark link plate (one plate) from the timing chain. Then, remove the mark link plate and the opposing plate from the timing chain.

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* If the pins are difficult to remove, press them out by inserting the temporary link from the timing chain kit into the pin holes from the front side of the engine. * Do not mix up the mark link plate, pins and plate of the timing gear with those of the timing chain kit.

* With the mark link plate (two plates) of the new timing chain facing the front of the engine, connect the new timing chain with the unlinked end of the old timing chain using a temporary link and clip.

* Remove the shop towels from the timing chain.

* Slowly crank the engine in the normal direction to rotate the timing chain so that the new timing chain takes the place of the old one.

* Stop cranking when the old timing chain is completely delivered and the temporary link comes to the top of the cam sprocket.

* Fill the space around the timing gear with shop towels again. Remove the temporary link and the timing chain.

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* Do not mix up the permanent link and the blue mark link plate when the temporary link and clip are removed.

* Remove
from the cylinder head.

* Install a permanent link from the rear of the engine to connect the two ends of the new timing chain.

* Attach a new mark link plate onto
-B

* Align the pins of the permanent link with the holes on the mark link plate. Mount
, and tighten
-A (shown in the illustration) until it cannot be tightened any further.

* Check that the pins of the permanent link project by the amount indicated in the illustration.

* Turn
around by 180 degrees and mount it so that the
-C is aligned with the mark link plate of the new timing chain.

* Tighten
-A (shown in the illustration) to 29 N·m {3 kgf·m} and flatten the end of each pin to stop the pins from coming off.

* Check that the pin ends are flattened to the width indicated in the illustration.

* Remove the shop towels from the timing chain and crank the engine slightly in the normal direction to apply a load on the timing chain.

* Check that the plunger of the new tensioner is locked in placed by the hook, then install it on the cylinder head with the new gasket. The gasket must be installed with its sealant applied surface directed toward the plunger.

* Crank the engine in the normal direction (clockwise as seen from the front of the engine).

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* The hook in the tensioner comes off when the engine is cranked in the normal direction (clockwise as seen from the front of the engine). If the engine is turned backward at this time, the tensioner could be damaged. Should the engine be turned backward by mistake, remove and check the tensioner and then reinstall it in the correct position again.

* With the No. 1 cylinder piston at TDC check that the punch marks on the cam sprocket is at the same place as before.

* Remove
from the cylinder head and reinstall the rocker cover.

Rocker Cover

* Disassembly sequence

1 Oil filler cap

2 Plate

3 Rubber

4 Rocker cover

5 Rocker cover gasket

X: Non-reusable parts

* Assembly sequence

Follow the disassembly sequence in reverse.

Tightening torque (Unit: N·m {kgf·m}

Lubricant and/or sealant

Installation procedure

Installation: Rocker cover gasket

* Mount the rocker cover gasket in the grooves of the rocker cover with their ends facing in the illustrated directions.

* Clean the sealant application surfaces of each part.

* Apply sealant to the joint surfaces of the cylinder head front and rear packings.

* Mount the rocker cover within three minutes of applying the sealant, being careful not to dislodge the sealant.

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* Do not run the engine within two hours of installing the rocker cover gasket. * Reapply sealant to the packings if any bolts are loosened or removed after installing the rocker cover gasket.

Cylinder Head And Valve Mechanism

* Disassembly sequence

1 Front packing

2 Rear packing

3 Tensioner

4 Gasket

5 Cylinder head bolt

6 Cylinder head bolt

7 Washer

8 Cylinder head (see later sections.)

9 Cylinder head gasket

*a Camshaft

*b Cam sprocket

*c Timing chain

*d Timing gear case

*e Crankcase

*f Front plate

P Locating pin

X Non-reusable parts

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* The cylinder head bolts (M12) are tightened using the torque-turn method. Any cylinder head bolt that has three marks indicating that the bolt has been tightened three times already must be replaced with a new one. * Do not detach the cam sprocket from the timing chain, as this can cause the whole chain to come off. If the chain comes off, remove the timing gear case assembly and reposition the chain. * New tensioner gaskets come with sealant already applied to the appropriate surfaces.

* Assembly sequence

Follow the disassembly sequence in reverse.

Tightening torque (Unit: N·m {kgf·m}

Lubricant and/or sealant

Special tools

Removal procedure

Removal: Cylinder head

* Check that the tensioner is not on the cylinder head. The cylinder head cannot be removed if the tensioner is installed.

* Apply a wrench as a stopper on the hexagonal portion to prevent the camshaft from rotating.

* The cam sprocket bolt has a left-hand thread. Remove the bolt by turning it in the direction opposite to the arrow on its head (the arrow indicates the direction for tightening the bolt).

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* Removing the bolt without using a stopper on the hexagonal portion of the camshaft will apply excessive load on the timing chain and cause damage. * Do not detach the cam sprocket from the timing chain unless absolutely necessary. Once disassembled, they must be reassembled according to a special procedure that includes positional adjustments.

* Loosen the cylinder head bolts (M8: 1, 2), (M12: 3 to 20) by turns in the order indicated in the illustration before they are removed in the same order.

* With the timing chain kept attached to the cam sprocket, remove the cylinder head by lifting it straight up.

* Hold the cam sprocket using
. Be careful not to drop the timing chain.

Installation procedure

Removal: Cylinder head gasket

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* When removing the cylinder head gasket, be careful not to scratch the cylinder head, the crankcase and the timing gear case.

Installation: Cylinder head

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* Before fitting the cylinder head bolts, check the punch marks on each bolt's head. (Bolts with one or two punch marks can be reused.)

* The cylinder head gasket comes in four sizes. Choose the gasket appropriate for the cylinder head by the following procedure.

* Measure the amount of piston projection for every cylinder. (See the PISTON AND CONNECTING RODS section.)

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* Replacement of the piston or connecting rod alters the piston projection. Always measure the amount of piston projection after either or both of them are replaced.

* Select a cylinder head gasket with the thickness appropriate for the measured maximum piston projection value from the following table

* The size class of the cylinder head gasket can be determined from the number of notches on the gasket edge.

* Install the cylinder head gasket on the crankcase in the direction shown. At this time, use care not to damage the cylinder head gasket.

* Clean the sealant application surfaces of each part.

* Apply sealant to the top surfaces of the areas where the timing gear case, the front plate and the crankcase join together (two places).

* Install the cylinder head together with the cylinder head gasket on the crankcase within three minutes of applying the sealant, being careful not to dislodge the sealant.

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* Do not run the engine within one hour of installing the cylinder head. Reapply sealant to the surfaces indicated above if any cylinder head bolts are loosened or removed.

* Tighten the cylinder head bolts by following different tightening procedure for the M12 bolts (1 to 18) and the M8 bolts (19 and 20). The bolts should be tightened in steps according to the following instructions.

Tightening procedure for bolts 1 to 18

* Apply engine oil to the threads and head's seating surface of each M12 cylinder head bolt. Tighten them to 98 N·m {10 kgf·m} in the order indicated in the illustration.

* Loosen the bolts in the opposite order, then retighten them to 49 N·m {5 kgf·m} in the order indicated in the illustration.

* Tighten the bolts further by 90° in the order indicated in the illustration.

* Then tighten the bolts further by 90° in the order indicated in the illustration again.

* After the tightening is completed, put a punch mark on each bolt head to indicate that it has been retightened.

Tightening procedure for bolts 19 and 20

* After completing the tightening procedure for bolts 1 to 18 (M12), tighten bolts 19 and 20 (M8) to 23 N·m {2.4 kgf·m}.

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* Cylinder head bolts M12 are tightened using the torque-turn method, and must never be additionally tightened after the final tightening.

* Apply a wrench as a stopper on the hexagonal portion to prevent the camshaft from rotating.

* Install and tighten the cam sprocket bolt by turning it in the direction of the arrow on its head.

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* Tightening the bolt without applying a stopper on the hexagonal portion of the camshaft will apply an excessive load on the timing chain and cause damage.

Installation: Tensioner

* Turn the cam of the tensioner, push in the plunger by hand and hold it in the retracted position with the hook.

* Install the tensioner, then crank the engine in the normal direction (to clockwise as seen from the front of the engine). This will undo the hook, and the ratchet mechanism inside the tensioner will start adjusting the tension of the timing chain.

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* Installing the tensioner without holding the plunger in the retracted position will apply an excessive load on the timing chain and cause damage. Always push in the plunger and hold it in the retracted position before installing the tensioner. * Do not crank the engine in the reverse direction (counter-clockwise as seen from the front of the engine) after installing the tensioner, as this will apply an excessive load on the plunger and cause damage. If you crank the engine in the reverse direction by mistake, remove the tensioner and inspect it for damage. The tensioner may be reinstalled if it is intact.

Installation: Front packing and rear packing

* Clean the sealant application surfaces of each part.

* Apply sealant to the front packing and rear packing evenly and without any breaks.

* Install the front packing and rear packing on the cylinder head within three minutes of applying the sealant, being careful not to dislodge the sealant.

Cylinder Head

* Disassembly sequence

1 Camshaft cap

2 Camshaft

3 Lifter shim

4 Valve lifter

5 Valve cotter

6 Upper retainer

7 Valve spring

8 Lower retainer

9 Valve stem seal

10 Intake valve

11 Exhaust valve

12 Connection plate

13 Glow plug

14 Injection nozzle (See Gr13.)

15 Gasket holder

16 Water joint

17 Water temperature sensor

18 Intake valve guide

19 Exhaust valve guide

20 Intake valve seat

21 Exhaust valve seat

22 Tablet

23 Combustion jet

24 Water director

25 Stud

26 Sealing cap

27 Sealing cap

28 Sealing cap

29 Sealing cap

30 Cylinder head

P Locating pin

X Non-reusable parts

* Assembly sequence

Follow the disassembly sequence in reverse.

* After assembly, inspect and adjust the valve clearances. (See "GENERAL INSPECTION AND ADJUSTMENT".)

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* When intake or exhaust valves are removed, their valve stem seals must be replaced.

Service standards (Unit: mm)

Tightening torque (Unit: N·m {kgf·m})

Lubricant and/or sealant

Special tools (Unit: mm)

Inspection before removal

Inspection: Camshaft end play

* If the end play measurement is not within the standard value range, replace the defective part(s).

Removal procedure

Removal: Valve cotters

<Method 1>

* Using
and
, remove and install the valve cotters by the following procedure.

* Install
on the cylinder head using any M8 x 1.25 mm bolts.

* Install
on
using any washers and M6 x 1 mm nuts.

* Set the stay parallel with the cylinder head.

* Adjust the retainer and the mobile nut so that the retainer holder presses down on the upper retainer from directly above, and fix them in place with the wing bolt. Adjust the vertical position of the retainer holder by raising or lowering the stay using the nuts.

* Turn the handle clockwise to press down on the upper retainer, thus removing the valve cotter.

<Method 2>

* Place a wood piece between the valve and
to protect the valve from damage.

* Using
, press down on the upper retainer to remove the valve cotter.

Removal: Tablets and combustion jets

* Insert a round bar or a similar tool into the glow plug mounting hole in the cylinder head. Remove the combustion jet and its tablet by lightly tapping on the round bar.

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* Do not strike the bar with force. The combustion jet is ceramics and is easily damaged under strong impact.

Inspection procedure

Inspection: Camshaft

(1) Cam lift

* If the lift of any cam is below the specified limit, replace the camshaft.

(2) Bend

* Support the camshaft at its No. 1 journal and No. 5 journal. Measure the extend of bend in the camshaft at the center of the No. 3 journal.

* Turn the camshaft through one revolution. One-half of the dial indicator reading represents the extent of bend.

* If the measurement exceeds the specified limit, replace the crankshaft.

(3) Oil clearance at the journals

Measure the oil clearance, and if the measured value is higher than the limit, replace the faulty parts.

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* Be sure to replace camshaft caps and cylinder head at the same time.

Inspection: Valve

* If a valve is replaced with a new one due to any result of the following inspections, be sure to lap the valve and valve seat.

(1) Stem diameter

* Replace the valve if the stem's outside diameter is below the limit or is severely worn.

(2) Valve seat angle

* If the measurement is out of the specified value, correct the valve.

(3) Valve margin

* Reface or replace the valve if the valve seat angle or valve margin exceeds the specified limits.

Refacing

* Limit grinding to a necessary minimum.

* If the valve margin is below the limit after grinding, replace the valve.

* After grinding, make sure to lap the valve and valve seat.

Inspection: Valve stem-to-valve guide clearance

* If the clearance exceeds the specified limit, replace the defective part(s).

Replacement of valve guides

[Removal]

[Installation]

* Measure the diameter of the valve guide mounting hole in the cylinder head.

* If the measurement exceeds the specified value, select an oversize valve guide from the table below.

* Recondition the valve guide mounting hole to the diameter corresponding to the diameter of the selected oversize valve guide.

Unit: mm

* Temporarily place the lower retainer on the cylinder head. Then, install the valve guide until the lower retainer touches
closely.

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* The valve guides must be pressed to a depth of 14 mm. Make sure to use to achieve this depth. * Exhaust valve guides are longer than intake valve guides. Make sure to install the correct type of guide in each location.

Inspection: Contact between valve and valve seat

* Before starting inspection, check that the valve and valve guide are intact.

* Apply an even coat of red lead to the valve contact surface of the valve seat.

* Strike the valve once against the valve seat. Do not rotate the valve during this operation.

* If the red lead deposited on the valve indicates a poor contact pattern, take either of the following corrective actions.

Lapping

Lap valves by using the following procedure.

* Apply a thin coat of lapping compound to the seat contact surface of the valve.

* Start with an intermediate-grit compound (120 to 150 grit) and finish with a fine-grit compound (200 grit or more).

* Adding a small amount of engine oil to the lapping compound can facilitate even application.

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* Do not put any compound on the stem.

* Strike the valve several times against the valve seat while rotating the valve a little at a time.

* Wash away the compound with diesel fuel.

* Apply engine oil to the valve contact surface of the valve seat and rub in the valve and seat well.

* Inspect the contact pattern of the valve and valve seat again.

* If the contact pattern is still defective, replace the valve seat.

Inspection: Valve seats

* If a valve is refaced or replaced with a new one due to any result of the following inspections, be sure to lap the valve and valve seat.

(1) Seat width

* If the measurement exceeds the limit, reface or replace the valve seat.

(2) Valve sinkage from cylinder head bottom surface

* Measure with the valve fully seated to the valve seat.

* If the measurement exceeds the limit, adjust or replace the defective part(s).

Refacing the valve seat

* Grind the valve seat using a valve seat cutter or valve seat grinder.

* Place a sandpaper of around #400 between the cutter and valve seat and grind the valve seat lightly.

* Use a 15° or 75° cutter to cut the valve seat to a width within the standard range.

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* Make sure that the valve seat refacing does not cause the valve sinkage to exceed the specified limit.

* Lap the valve and valve seat.

Replacement of valve seat

[Removal]

* The valve seats are installed by expansion fitting. To remove a valve seat, grind inside the metal stock to reduce the wall thickness, then remove the valve seat at room temperature.

[Installation]

* Measure the diameter of the intake or exhaust valve seat hole A or B in the cylinder head.

* If the measurement exceeds the following value, select an oversize valve seat from the table below.

A Intake valve seat hole diameter 43 ^+0.025₀ mm

B Exhaust valve seat hole diameter 37 ^+0.025₀ mm

* Machine the valve seat mounting hole to diameter A or B and depth C or D (see illustration) to accommodate the diameter and depth of the selected oversize valve seat.

Unit: mm

* If any abnormality is found, replace the cylinder head.

* Chill the valve seat thoroughly by immersing it in liquid nitrogen.

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* Handle the chilled valve seats extremely carefully to avoid getting frostbites.

* Install the valve seat in the cylinder head using
and
(for intake valve seat) or
(for exhaust valve seat).

* Lap the valve seat and valve.

Inspection: Cylinder head bottom surface distortion

* If the distortion exceeds the specified limit, rectify it using a surface grinder. Make sure that the height of the cylinder head from the top surface to the bottom surface is not reduced to a value below the specified limit.

Installation procedure

Installation: Sealing caps

* Apply sealant to the press fitting hole A in the cylinder head.

* Install sealing caps and press them in to the depths respectively specified in the illustration.

Installation: Water director

* Install the water director to the specified depth with the notch A facing in the illustrated direction.

Installation: Tablets and combustion jets

* Install the combustion jet such that it is pressed closely against contact surface A of the combustion chamber in the cylinder head.

* After installing the combustion jet, install the tablet in the cylinder head such that it is pressed closely against contact surface B on the combustion jet.

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* When replacing the combustion jet, make sure to replace the tablet simultaneously. * Do not strike the tablet with force, as it is ceramics and is easily damaged under strong impact.

Installation: Valve stem seal

* Apply engine oil to the lip of the valve stem seal.

* Install the valve stem seal until
sits snugly on the cylinder head.

* After installing the valve stem seal, check that its spring is not deformed or damaged. Replace the valve stem seal if the spring is defective.

Installation: Valve cotter

* To install the valve cotter, follow the removal procedure. (See " Removal: Valve cotter".)

Installation: Lifter shims

Lifter shim makes valve clearance conform to the standard value. Use the following procedure to install:

* Select at random lifter shim and replace valve lifter temporarily.

* Mount camshaft to cylinder head and mount camshaft caps.

* Measure valve clearance using feeler gauge with the cam position at the range as illustrated, at the center of lifter shim and record the measurements.

* Be sure that when taking measurements using feeler gauge that some resistance is felt when inserting the gauge. If the gauge can be inserted freely without any resistance, an accurate measurement cannot be obtained.

* For any valves where the cam does not come within range at the center of lifter shim, adjust and correct the cam position by rotating camshaft or remove the shaft and reposition it to the measure valve clearance.

* Based on the result of the measured value, select lifter shims of proper thickness to conform to the standard valve clearance.

* For the valve clearance, see "GENERAL INSPECTION AND ADJUSTMENT" in this group.

A: Thickness of lifter shim 2.250 to 3.150 mm (Total of 37 in 0.025 mm increments)

B: Size stamp ("2275"=2.275 mm thick) Thickness of shim to be selected=Clearance between shim surface and cam contact surface + (Measured value - Standard value)

Piston and Connecting Rod

* Disassembly sequence

1 Lower connecting rod bearing

2 Connecting rod cap

3 Upper connecting rod bearing

4 Piston and connecting rod (See later sections.)

*a: Upper crankcase

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* The connecting rod bolts are fastened using the torque-turn method. Any connecting rod cap installation nut that has three marks indicating that it has been tightened three times already must be replaced with a new bolt together with its nut.

* Assembly sequence

Follow the disassembly sequence in reverse.

Service standards (Unit: mm)

Tightening torque (Unit: N·m {kgf·m})

Lubricant and/or sealant

Special tools (Unit: mm)

Inspection before removal

Inspection: Piston projection from crankcase top surface

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* The amount of piston projection affects engine performance and must therefore be inspected without fail.

* Set the piston at the top dead center.

* Mark reference points A (five points in total) on the top surface of the upper crankcase as shown in the illustration. Using each of the marks as a zero point, measure the amount of piston projection relative to the zero point (height of measurement point B - height of reference point A).

* Make the measurements at the four measurement points B for each cylinder (16 points in total) using the reference point A nearest to each measurement point, and calculate the average value of all the measurements.

* If the average value is out of the standard value range, check the clearances between all relevant parts.

* Select and use a cylinder head gasket that can accommodate the average piston projection (average value of the 16 measurements). (See the CYLINDER HEAD section.)

Inspection: Connecting rod end play

* Measure the end play for every connecting rod.

* If any measurement exceeds the specified limit, replace the defective part(s).

Inspection procedure

Inspection: Connecting rod bearing span when free

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* Do not attempt to manually expand the bearings.

* If the measurement is less than the limit, replace upper and lower bearings as a set.

Inspection: Connecting rod bearing-to-crankshaft clearance (oil clearance)

* Fit the lower bearing to the connecting rod cap and the upper bearing to the connecting rod, then tighten the nut to a torque of 49 N·m {5 kgf·m}.

* Measure the inside diameter of the bearing and the diameter of the crankshaft pin.

* If the clearance exceeds the limit, replace the defective part(s).

* If a bearing has to be replaced with an undersized one, machine the crankshaft pin to the specified undersize diameter. (See the CRANKSHAFT section.)

Inspection: Piston-to-Upper crankcase cylinder clearance

* If the measurement is not within the standard value range, do one of the steps below according to the condition.

C: Cylinder bore measurement (in direction of crankshaft axis)

D: Cylinder bore measurement (in direction perpendicular to crankshaft axis)

E: Piston diameter measurement (in direction perpendicular to piston pin hole)

* If the cylinder bore diameter exceeds the specified limit, re-bore all the cylinders to an oversize diameter and replace the pistons and piston rings with the corresponding oversize ones.

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* If any one cylinder is found to be defective and must be rebored, all the other cylinders must also be rebored to the same oversize.

* If the cylinder bore diameter is within the standard value range, replace the piston and piston rings.

Selection of oversize piston

* Available oversizes: 0.50 mm and 1.00 mm (two sizes)

* Measure the bore diameter of each cylinder. Select the appropriate oversize piston based on the largest of the measurements.

* Measure the outside diameter of the chosen oversize piston.

* Rebore each cylinder to a diameter at which the piston-to-cylinder clearance will be within the standard value range.

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* Rebore the cylinders in the following order to prevent the generated heat from causing distortions in the crankcase.

Installation procedure

Installation: Connecting rod bearings

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* Do not reverse the positions of the lower bearing and the upper bearing (with oil hole) when installing, as this may cause seizure in the engine.

* Select and use a bearing set of a thickness that can accommodate the inside diameter of the connecting rod's big end and the diameter of the crankshaft pin. Use either of the following methods for the selection.

(1) Measurement based selection

* Install the connecting cap on the piston and connecting rod assembly without fitting the lower and upper bearings.

* Tighten the connecting bolt nuts to 49 N·m {5 kgf·m}.

* Measure the inside diameter of the connecting rod's big end (vertically from one point), and the outside diameter of the crankshaft pin (vertically or horizontally from one point).

* Select a bearing set that matches the measurements from the table below. If the color identification mark is indiscernible, measure the thickness of the bearing walls and use the measurements in its place.

(Unit: mm)

(2) Color identification mark based method

* The connecting rods, crankshaft, and bearings can be appropriately combined in the following ways according to their color identification marks:

Each crankshaft also has a size mark ("1" or "2") indicating the diameter of each pin.

Installation: Piston and connecting rod

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* Before installing the piston and connecting rod, check the punch marks on each nut's top surface. The nut and its bolt can be reused if there are two or less punch marks. * The punch marks indicate the number of times each bolt has been tightened using the torque-turn tightening method. Any connecting rod bolt and nut that already has three punch marks must be replaced.

* Check that the piston ring end gaps are in their correct positions.

A. 1st compression ring gap

B. 2nd compression ring gap

C. Oil ring gap

D. Oil ring expander spring gap

O Front mark on piston

* If the cylinder has not been machined to an oversize, check that the size marks ("A", "B" or "C") on the piston and the upper crankcase are the same.

* Cover the connecting rod bolts with vinyl hoses to prevent them from scratching the crankshaft pin and the wall surface of the cylinder in the upper crankcase.

* Face the front mark "O" of the piston toward the front of the engine and install the piston.

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* Make sure that the piston and connecting rod do not hit the oil jet during installation.

* After installing the piston and connecting rod assembly, align the lugs on the connecting rod and connecting rod cap and tighten the nuts alternately in the following manner.

* Tighten the nut to a torque of 29 N·m {3 kgf·m}.

* Tighten the nut further to a torque of 49 N·m {5 kgf·m}.

* Tighten the nut further by turning it clockwise by 45° ± 5°.

* Then, turn it clockwise again by 45° ± 5°. Put a punch mark on the nut's top surface to indicate the number of times that it has been used.

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* The nuts that have been tightened using the torque-turn method must never be additionally tightened after the final angular tightening.

* Disassembly sequence

1 1st compression ring

2 2nd compression ring

3 Oil ring

4 Snap ring

5 Piston pin

6 Connecting rod bushing

7 Connecting rod bolt

8 Connecting rod

9 Piston

X Non-resusable parts

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* Do not remove the connecting rod bolt unless defects are evident.

* Assembly sequence

Follow the disassembly sequence in reverse.

Service standards (Unit: mm)

Lubricant and/or sealant

Special tools (Unit: mm)

Removal procedure

Removal: Piston ring

Removal: Piston pin

* Remove the piston pin by striking it with a rod and hammer.

* If the piston pin is difficult to remove, first heat the piston in hot water or with a piston heater.

Inspection procedure

Inspection: Piston ring end gap

* Using the crown of a piston, push the piston ring horizontally into a cylinder in the crankcase until it reaches the lower part of the cylinder, where there is relatively small wear.

* Taking care not to move the piston ring, measure the end gap.

* If any of the rings has a gap exceeding the specified limit, replace all the piston rings as a set.

Inspection: Piston ring side clearance in piston groove

* Remove any carbon deposits from the ring groove in the piston.

* Measure the side clearance of each ring around the piston's entire periphery.

* The 1st compression ring is full-keystone type. Measure the side clearance for this compression ring with a thickness gauge while pressing the ring against the piston with a straight edge.

* If any of the measurements exceeds the specified limit, replace the defective part(s). If any of the piston rings is defective, replace all the rings on the piston as a set.

Inspection: Piston pin-to-piston clearance

* If any of the measurements exceeds the specified limit, replace the bushing.

Inspection: Piston pin-to-connecting rod bushing clearance

* If the measurement exceeds the specified limit, replace the defective part(s).

Replacement of connecting rod bushing

* Replace the connecting rod bushing using
.

[Removal]

* Remove the upper bearing (if fitted) from the big end of the connecting rod.

* Mount the connecting rod on the base and lock it in position with the bracket and plate.

* Fit collar A over the puller with its ends in the illustrated directions. Then, slowly apply a pressure of approximately 49 kN {5000 kgf} to the puller with a press to force out the connecting rod bushing.

[Installation]

* Apply engine oil to the outside surface of the connecting rod bushing and the bushing fitting surface of the connecting rod.

* Fit collar B, the bushing, and collar A over the puller in the illustrated directions and lock this arrangement together with the nut.

* Align the oil holes in the connecting rod bushing and the connecting rod. Then, use a press to slowly apply a pressure of approximately 49 kN {5000 kgf} to the puller until the bushing is forced into place.

* After press-fitting the connecting rod bushing, measure the clearance between the piston pin and connecting rod bushing.

* If the measurement is less than the standard clearance range, ream the bushing.

Inspection: Connecting rod bend and twist

* Mount the connecting rod on the connecting rod aligner. Also mount the connecting rod bearings, piston pin, and connecting rod cap to create the same conditions as are expected when the connecting rod is mounted on a crankshaft. Tighten the nuts of the connecting rod bearing cap to a torque of 49 N·m {5 kgf·m}.

* Measure the extend of bend and twist in the connecting rod.

* If either measurement exceeds the specified limit, replace the connecting rod.

Inspection procedure

Installation: Connecting rod bolts

* Check that there are no burrs or other defects on the surfaces of the connecting rod bolt holes. Replace the connecting rod if defects are evident.

* Apply engine oil to the knurled surface of the connecting rod bolt. Then, install the bolt by using a press to slowly apply a pressure of approximately 4.9 kN {500 kgf} to it with the cuts of the bolt head facing in the illustrated directions.

Installation: Piston to connecting rod

* When replacing the piston and the connecting rod, select and install the appropriate piston by the following procedure.

* Install the connecting rods marked with the same mass mark for each engine.

* If the cylinders have not been machined to an oversize, make sure that the pistons and upper crankcase all have the same size mark ("A", "B", or "C"). The size is indicated on the upper crankcase for each cylinder.

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* Do not use a piston with a different size mark from the mark made on the upper crankcase for the corresponding cylinder, as this will cause seizure in the engine.

* Apply engine oil to the piston pin, and assemble the piston and connecting rod with their marks facing in the illustrated directions.

O: Front mark

* If the piston pin is difficult to insert, heat the piston in hot water or with a piston heater.

Installation: Piston rings

* With the manufacturer's marks (found near the piston ring end gaps) facing up, install the piston rings so that the end gap of each ring is positioned as illustrated.

A: 1st compression ring end gap

B: 2nd compression ring end gap

C: Oil ring end gap

D: Oil ring's expander spring end gap

O: Front mark on piston

The manufacturer's marks are present only on the 1st and 2nd compression rings.

Flywheel

* Disassembly sequence

1 Flywheel housing

2 Pointer

3 Ring gear

4 Flywheel

P Locating pin

* Assembly sequence

Follow the disassembly sequence in reverse.

Service standards (Unit: mm)

Tightening torque (Unit: N·m {kgf·m})

Lubricant and/or sealant

Work before removal

Inspection: Flywheel housing installation (eccentricity at the socket joint portion)

* Turn the crankshaft and check eccentricity at the socket joint portion of flywheel housing.

* If the eccentricity exceeds the limit, carry out reassembly.

* If the eccentricity still exceeds the limit after reassembly, replace the defective part.

Inspection: Flywheel installation (runout)

* If the measured value is higher than the limit, check the fastening bolt, the attachment surface of crankshaft, and depending on the condition found, either repair or replace flywheel.

Removal procedure

Removal: Ring gear

* Heat the ring gear evenly with a gas burner or the like until it reaches approximately 200°C, then remove it from the flywheel.

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* You could get burnt if you touch the heated ring gear.

Installation procedure

Installation: Ring gear

* Heat the ring gear evenly with a gas burner or the like until it reaches approximately 200°C.

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* You could get burnt if you touch the heated ring gear.

* Fit the ring gear with the side having non-chamfered tooth edges toward the flywheel.

Timing Gear Case

* Disassembly sequence

1 Crankshaft pulley

2 Front oil seal

3 Timing gear case

4 Key

5 Cover

6 O-ring

P Locating pin

X Non-reusable parts

* Parts marked with
are installed from the front plate side.

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* Do not remove the front oil seal unless defects are evident.

*

Follow the disassembly sequence in reverse.

Lubricant and/or sealant

Installation procedure

Installation: Front oil seal

* Install the front oil seal with its ends facing as illustrated so that end surface A of the oil seal is flush with end surface B of the timing gear case.

Installation: Timing gear case

* Clean the sealant application surface of each part.

* Apply a bead of sealant to the front plate mounting surface of the timing gear case evenly and without any breaks.

* Install the timing gear case within fifteen minutes of applying the sealant, being careful not to dislodge the sealant.

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* Do not run the engine within one hour of mounting the timing gear case. * If the timing gear case mounting nuts or bolts are loosened or removed, be sure to reapply sealant.

Timing Gears

* Disassembly sequence

1 Cam sprocket

2 Timing chain

3 Tension lever

4 Tension lever shaft

5 Eyebolt

6 Oil jet

7 Guide plate

8 Idler washer

9 Idler sprocket bushing

10 Idler gear and sprocket

11 Idler shaft

*a Crankshaft gear

*b Injection pump gear

*c Oil pump gear

P Locating pin

X Non-reusable parts

* Assembly sequence

Follow the disassembly sequence in reverse.

* After tightening the tension lever shaft mounting bolt, check that the tension lever moves smoothly.

* The idler shaft also serves as a locating component for the front plate.

Service standards (Unit: mm)

Tightening torque (Unit: N·m {kgf·m})

Lubricant and/or sealant

Special tools (Unit: mm)

Inspection before removal

Inspection: Timing chain elongation

* Support the cam sprocket with
.

* Align the inscribed lines on the adjusting plate and the nut to adjust the cam sprocket position to its normal position.

* Push the tension lever by hand to make the timing chain taut.

* Check the amount of elongation of the timing chain by measuring the smallest distance between the two chain portions (see the illustration).

* Replace the timing chain if the measured distance is below the specified limit.

Inspection: Backlash between gears

* For each pair of gears, measure the backlash at more than three teeth.

* If any of the measurements exceeds the specified limit, replace the defective part(s).

Inspection: Idler gear end play

* If the measurement exceeds the specified limit, replace the defective part(s).

Inspection procedure

Inspection: Tension lever

* Check the timing chain sliding surface and point of contact of the tension lever for cracking or flaking.

* Replace the tension lever if defects are evident.

Inspection: Tension lever-to-tension lever shaft clearance

* Replace the defective part(s) if the clearance exceeds the specified limit.

Inspection: Guide plate

* Check the timing chain sliding surface of the guide plate for cracking or flaking.

* Replace the guide plate if defects are evident.

Inspection: Idler sprocket bushing-to-idler shaft clearance

* If the measurement exceeds the specified limit, replace the bushing.

Replacement of idler sprocket bushing

[Removal]

[Installation]

* Place the idler gear and sprocket with its ends facing as illustrated.

* Press-fit the idler gear bushing until
sits snugly on the chamfered end of the idler gear and sprocket.

* After press-fitting the bushing, measure the clearance.

* If the measurement is less than the minimum of the standard value range, ream the idler gear bushing until the clearance falls within the standard value range.

Installation procedure

Installation: Idler gear and sprocket

* Install the idler gear and sprocket while aligning the marks "1" on its teeth with the corresponding mark on one of the crankshaft gear teeth.

Installation: Timing chain

* Support the cam sprocket with
.

* Check that the idler gear and sprocket and the crankshaft gear are engaged at the "1" marked teeth.

* Align the "0" mark on the idler gear and sprocket with the mark link plate (one plate) on the timing chain.

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* The timing chain has mark link plates in two locations (one with one mark link plate and the other with two mark link plates). Do not confuse the two locations when carrying out this procedure.

* Install the timing chain with the mark link plates (two plates) aligned with the "0" marks on the cam sprocket.

* After installing the timing chain, install the idler washer so that the front mark "F" is facing forward.

Crankshaft and Crankcase

* Disassembly sequence

1 Front plate

2 Dust cover

3 Rear plate

4 Rear oil seal

5 Rear oil seal case

6 Main cap bolt

7 Lower main bearing

8 Lower crankcase

9 Lower thrust plate

10 Upper thrust plate

11 Crankshaft gear

12 Key

13 Crankshaft

14 Upper main bearing

15 Check valve

16 Oil jet

17 Upper crankcase

P Locating pin

X Non-reusable parts

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* The lower crankcase and upper crankcase are manufactured as paired parts, and therefore must always be replaced as a set.

* Assembly sequence

Follow the disassembly sequence in reverse.

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* The main bearing cap bolts are tightened using the torque-turn tightening method. Any bolt that has three punch marks must be replaced. * Do not overtighten the check valve. If it is tightened to a torque exceeding the specification, the check valve may malfunction, resulting in seizures in the engine.

Service standards (Unit: mm)

Tightening torque (Unit: N·m {kgf·m})

Lubricant and/or sealant

Special tools

Inspection before removal

Inspection: Crankshaft end play

* If the measurement exceeds the specified limit, replace the thrust plates with oversize ones.

* Available oversizes: +0.15 mm, +0.30 mm, +0.45 mm

* Replace the crankshaft if the end play is too large to adjust using oversize thrust plates.

Removal procedure

Removal: Lower crankcase

* Loosen the bolts in several passes in the order indicated in the illustration (1 to 16).

* After loosening the bolts, loosen the main cap bolts in several passes in the order indicated in the illustration (17 to 26), then remove the main cap bolts.

Removal: Crankshaft gear

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* Attach a plug (M16 x 1.5 mm, length 30 mm) on the end of the crankshaft to prevent any damages by . * Do not tap off the crankshaft gear as this can damage it.

Inspection procedure

Inspection: Main bearing span when free

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* Do not attempt to manually expand the bearings.

* If the measurement is less than the limit, replace upper and lower bearings as a set.

Inspection: Main bearing-to-crankshaft oil clearance

* Fit the upper bearing into the upper crankcase and the lower bearing into the lower crankcase.

* Tighten the main bearing cap bolts to a torque of 20 N·m {2.0 kgf·m}.

* Measure the inside diameter of the main bearing and the diameter of the corresponding crankshaft journal.

* If the difference between the measurements exceeds the specified limit, machine the crankshaft journal to one of the specified dimensions indicated on the next page.

Inspection: Crankshaft

(1) Bend

* Support the crankshaft at its No. 1 journal and No. 5 journal. Measure the extend of bending in the crankshaft at the center of the No. 3 journal.

* Turn the crankshaft through one revolution. One-half of the dial indicator reading represents the extent of bending.

* If the measurement exceeds the specified limit, replace the crankshaft.

(2) Out-of-roundness and taper of crankshaft journals and pins

* If any of the measurements exceeds the specified limits, grind the crankshaft journal(s) and/or pin(s) to undersize(s) or replace the crankshaft.

Grinding of crankshaft

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* If the crankshaft is ground to an undersize, the main bearings must be replaced with the undersize ones of the corresponding undersize.

* Do not change the center-to-center distance A between the journal and pin.

A 50 ± 0.05 mm

* Do not change the journal width B and the pin width C.

B 27.5 mm (for No. 1 journal) 30 mm (for No. 2 to No. 5 journals)

C 35 mm

* Finish the fillets D smoothly.

D R 3.5 mm

* Carry out a magnetic inspection to check for cracks possibly caused by grinding. Also, check that the hardness of the surface has not dropped below Shore hardness number (Hs) 75.

* Replace the crankshaft if defects are evident.

Crankshaft undersize dimensions (Unit: mm)

* When grinding, turn both the crankshaft and the grinder counterclockwise as viewed from the crankshaft front end.

* When finishing the crankshaft with whetstone or sandpaper, rotate the crankshaft clockwise.

Inspection: Distortion of upper crankshaft top surface

* If the measurement exceeds the specified limit, grind the crankcase top surface with a surface grinder.

* Limit the amount of removed metal to make sure that the amount of piston projection above the crankcase top surface stays within the standard value range.

Installation procedure

Installation: Crankshaft gear

* Heat the crankshaft gear to approximately 100°C with a gas burner or the like.

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* You could get burnt if you touch the heated ring gear.

* Align the key fitted in the crankshaft with the slot in the crankshaft gear. Drive the gear into position by lightly striking its end face with a plastic hammer.

Installation: Thrust plates

* Install the thrust plates on the rearmost main bearing cap and crankcase with the oil grooves on the inner plates facing inward and those on the outer plates outwards as shown in the illustration.

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* Be sure to orient the oil grooves as indicated above, otherwise seizures may occur in the engine.

* Use oversize thrust plates when adjusting the crankshaft end play. The upper and lower thrust plates on the same side must be of the same size. The thrust plates on one side may differ in size from those on the other side.

Installation: Main bearings

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* The upper main bearing has an oil hole while the lower main bearing does not. Do not confuse the two, as incorrect installation can cause seizures in the engine.

* Select and use a main bearing set of a thickness that can accommodate the inside diameter of each main bearing fitting hole between the upper crankcase and lower crankcase and the diameter of the corresponding crankshaft journal. Select the appropriate main bearing set by one of the two following methods.

(1) Measurement based selection

* Mount the upper crankcase on the lower crankcase without fitting main bearings.

* Tighten the main cap bolts to 20 N·m {2.0 kgf·m}.

* Measure the inside diameter of the main bearing fitting hole between the upper crankcase and lower crankcase (vertically from one point), and the diameter of the crankshaft journal (vertically or horizontally from one point).

* Select a main bearing set that matches the measurements from the table below. If the color identification mark is indiscernible, measure the thickness of the bearing walls and use the measurements in its place.

(Unit: mm)

(2) Color identification mark based method

* The crankshaft, upper crankcase, and main bearing can be appropriately combined in the following ways according to their color identification marks:

No. 1: Position of color identification mark on No. 1 journal

No. 2: Position of color identification mark on No. 2 journal

No. 3: Position of color identification mark on No. 3 journal

No. 4: Position of color identification mark on No. 4 journal

No. 5: Position of color identification mark on No. 5 journal

Installation: Lower crankcase

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* Before installing the main cap bolt, check the punch marks on each bolt's head. (Bolts with one or two punch marks can be reused.) * The punch marks indicate the number of times each main cap bolt has been tightened using the torque-turn tightening method. Any main cap bolt that already has three punch marks must be replaced.

* Clean the sealant application surfaces of each part.

* Apply a bead of sealant to the upper crankcase evenly and without any breaks as shown in the illustration.

* Install the lower crankcase within three minutes of applying the sealant to the upper crankcase, being careful not to dislodge the sealant.

* Apply engine oil to the threads and seating surface under the head of each of the main cap bolts, and tighten the bolts to a torque of 20 N·m {2.0 kgf·m} in the order indicated in the illustration (1 to 10).

* Then, tighten the main cap bolts further by 90 degrees in the same order.

* Tighten them by another 90 degrees in the same order.

* After completing tightening of the main cap bolts, tighten the bolts (11 to 26) to the specified torque in the numbered order (see the illustration).

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* Do not run the engine within one hour after installing the bolts. * Reapply sealant to the upper crankcase if any of the main cap bolts and the other bolts are loosened or removed.

* Make a punch mark on the head of each main cap bolt to indicate the number of times it has been used.

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* The main cap bolts are tightened using the torque-turn method and must never be additionally tightened after the final angular tightening.

* After installing the lower crankcase, check that the crankshaft can be rotated lightly by hand. Inspect the main bearing cap fitting holes if the crankshaft does not rotate smoothly.

Installation: Rear oil seal

* Install the rear oil seal in the rear oil seal case so that its ends face in the illustrated directions and the upper end surface of the oil seal shown in the illustration is flush with the upper end surface of the rear oil seal case.

Installation: Rear oil seal case

* Apply engine oil to the rear oil seal lip.

* Clean the sealant application surface.

* Apply an evenly thick bead of sealant to the rear oil seal case without any breaks as shown in the illustration.

* Install the rear oil seal on the crankcase assembly within three minutes of applying the sealant, being careful not to dislodge the sealant.

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* Do not run the engine within an hour of installing the rear oil seal case. * Reapply sealant to the rear oil seal case if any bolts are loosened or removed.

Installation: Front plate

* Clean the sealant application surfaces of each part.

* Apply evenly thick beads of sealant to the crankcase assembly without any breaks as shown in the illustration.

* Install the front plate within three minutes of applying the sealant, being careful not to dislodge the sealant.

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* Do not run the engine within an hour of installing the front plate. * Reapply sealant to the crankcase assembly if any of the bolts is loosened or removed. All the bolts other than the four bolts shown in the illustration are for fastening both the front plate and timing gear case. Use any suitable bolts in place of these bolts to keep the front plate temporarily in place.