MITSUBISHI ENGINES REF. 4D31 ENGINE FOR Caterpillar

5. Service Procedures

Usage:

5-1 Engine Proper

5-1-1 Measurement of Compression Pressure

Compression pressure must be measured prior to disassembly of the engine.

Measure the compression pressure at regular intervals and keep track of its changes. During the break-in period or after parts have been replaced with new ones, there is a slight increase in the pressure as the piston rings and valve seats fit snugly in position. As rough edges and friction between parts are gradually reduced, the pressure comes down.

Measurement Procedure

(1) Retighten the cylinder head bolts to specified torque and let the engine warm up until the coolant temperature reaches 75°C to 85°C.

(2) Remove all injection nozzles <4D31, 4D31-T> or glow plugs <4D30, DR> from the cylinder head.

To remove the glow plugs, use Socket Wrench (special tool).

NOTE: Cover the mounting holes and injection pipes to prevent entry of dust and dirt.

(3) Install Compression Gauge Adaptor (special tool) on the injection nozzle or glow plug mounting hole together with a gasket and connect the compression gauge (measuring instrument).

(4) Turn the engine with the starter and read the compression gauge pointer value with the specified engine speed.

NOTE:

1. Keep no fuel injected.

2. Make sure that the enigne speed is also measured as compression pressure varies with the engine speed.

3. Make measurement for all cylinders, as wear and other conditions vary from one cylinder to another.

(5) If the measurement is below the limit, disassemble and check.

5-1-2 Cylinder Head and Valve Mechanism

(1) Removal and Installation

For disassembly of parts with an encircled number, see following items.

Removal Procedure

(a) Where the push rod is forcing up the rocker, the rocker adjusting screw must be loosened before all cylinder head bolts are removed.

(b) Loosen the cylinder head bolts in the reverse order of tightening.

(c) Remove the rocker and bracket assembly and cylinder head assembly, raising them straight upward.

(d) When removing the cylinder head gasket, use care to prevent scratches on the cylinder head and crankcase.

(e) Removal of the tappet <D3>

Remove the tappet, using Tappet Extractor (special tool). For removal, press the special tool until its O-ring is pressed tightly against each other and remove the tappet together with the special tool.

Installation Procedure

(a) Install the cylinder head assembly and rocker and bracket assembly to align the locating pins.

(b) Tighten the cylinder head bolts in the sequence shown in illustration. Tighten step by step, and as a final step, tighten to specified torque.

(2) Disassembly

(a) Rocker and bracket assembly

1 Set bolt <D3,4DR5>

Set screw <6DR5>

2 Retainer <6DR5>

3 Rocker shaft bracket

4 Rocker

5 Rocker shaft spring

6 Rocker shaft

(b) Cylinder head assembly

For disassembly of parts with an encircled number, see following items.

1) To remove the valve cotter, use Valve Lifter (special tool) and compress evenly the valve spring.

2) Whenever the valve stem seal or valve is removed, the valve stem seal must be replaced with a new one.

3) Remove the water director if corroded.

4) If cracks and fusion are evident on the chamber jet, insert a rod through the glow plug hole and tap it to drive out the chamber jet. <4D30, DR only>

(3) Inspection

(a) Rocker and bracket assembly

1) Using the rocker I.D. and rocker shaft O.D., calculate the clearance. If the limit is exceeded, replace the bushing in the rocker. For replacement, use Rocker Bushing Puller (special tool).

NOTE:

1. Align the oil hole in the bushing with that in the rocker.

2. Ensure that the bushing clinch is on the adjusting screw end.

3. When press-fitting the bushing into rocker, start with the chamfered side on the rocker.

(b) Cylinder head assembly

1) Inspection of valve spring

Check the valve spring for squareness, free length, and proper tension, and replace if the limit is exceeded.

2) Tappet to crankcase clearance <D3>

If the clearance exceeds the limit, replace the tappet.

3) Measure the push rod runout.

If the limit is exceeded, replace.

4) Cylinder head bottom surface distortion

If the limit is exceeded, correct with a surface grinder.

If the cylinder head height from top to bottom surface is below the limit, replace.

5) Measure the valve stem O.D. and, if the measurement is below the limit, replace.

6) Calculate the clearance with the valve guide I.D. and valve stem O.D. If the limit is exceeded, replace the valve guide.

7) Replacement of valve guide

For removal of the valve guide, use the Valve Guide Remover (special tool).

To install, use Valve Guide Installer (special tool) and ensure that the special tool is positively seated on the cylinder head. The pressing force is specified for the valve guide, which must be reached by using the special tool.

8) Inspection of valve

Check the contacting condition of the valve seat and valve, after inspection and replacement of the valve guide.

When the valve is pressed against the valve seat coated with red lead, make sure that the valve is not turned.

9) Correction of valve face

Grind the valve face with a valve refacer, the grinding dimension being limited to a minimum.

NOTE:

1. The valve seat angle is 45°.

2. Correct to ensure that the valve margin is up to the limit.

10) Correction of valve seat

a) Grind with a valve seat cutter or valve seat grinder.

b) After grinding, hold a #400 or similar sand paper between the cutter and valve seat and regrind lightly.

NOTE:

1. The valve seat angle is 45°.

2. Correction must be made to ensure the valve seat width and valve sinkage are within the limit.

c) Using a 15° or 75° cutter, correct the seat width to the nominal value.

d) Seat the valve and valve seat. [See 12)]

11) Replacement of valve seat

The valve seat is cold fitted. Replacement procedure is given below.

a) Grind the valve seat from inside to reduce the wall thickness. Then, remove it at normal temperature.

b) Check if there is sufficient interference between the cylinder head and valve seat.

c) Dip the valve seat into liquid nitrogen and let it cool down. But heat the cylinder head sufficiently.

d) Using Caulking Tool Body and Caulking Ring (special tools), install the valve seat.

NOTE: After pressing in position the valve seat with the chamfered side of the caulking ring, face the ring in the opposite direction to caulk the cylinder head.

e) Reface the valve seat to obtain the nominal values for the seat width and valve sinkage.

12) Seating of valve and valve seat

The valve and valve seat must be in even contact throughout the surfaces.

Whenever the valve or valve seat is corrected or replaced, they must be seated.

a) Apply a thin coat of compound evenly to the seating surface of the valve.

NOTE:

1. Make sure that there is no compound on the stem of the valve.

2. Use intermediate mesh compound (120 to 150 meshes) first and then use fine mesh compound (200 meshes or more) for the finish.

3. Mix the compound with a small amount of engine oil and the compound can be applied evenly.

b) Using Valve Lapper (special tool), seat the valve on valve seat.

While turning the valve slightly at a time, strike it against the valve seat.

c) Wash off the compound with gas oil or similar object.

d) Seat the contact surfaces with engine oil.

e) Check if they are properly seated.

(4) Reassembly

(a) Rocker and bracket assembly

(b) Cylinder head assembly

1) Installation of chamber jet <4D30, DR>

<4D30>

Locate the chamber jet with Chamber Jet Guide (special tool) and drive it into place.

<DR>

Install the chamber jet so that its opening line runs parallel with the centerline of cylinder head.

If interference is insufficient, replace it with an oversize.

2) Installation of water director

Install the water director with its cut facing toward the specified direction.

3) Installation of valve stem seal

Apply engine oil to the lips of the valve stem seal and strike Valve Stem Seal Installer (special tool) until it touches the cylinder head.

4) Installation of valve cotter

Using Valve Lifter (special tool), install the valve cotter while compressing the valve spring.

NOTE: When compressing the valve spring, do not allow the upper retainer to be in contact with the valve stem seal.

5-1-3 Flywheel and Rear Plate

(1) Disassembly and Inspection

For disassembly of parts with an encircled number, see following items.

Removal Procedure

(a) Removing flywheel

Remove the flywheel by inserting flywheel mounting bolts evenly into the flywheel removing holes.

Remove the ring gear integral with the flywheel.

(b) The flywheel housing of the 6DR5 series has a pointer mounted. Do not remove this pointer at the time of disassembly.

Inspection Procedure

(a) Replacement of ring gear

1) Removal

Using an acetyline torch or similar device, evenly heat the ring gear.

By applying a protective rod, hammer the entire periphery of the ring gear, forcing it off.

2) Installation

Heat the ring gear with piston heater (approx. 100 °C) for three minutes.

Fit the ring gear onto the flywheel with the nonchamfered side of tooth crests toward the flywheel.

(b) Friction surface distortion

Place the flywheel on a surface plate and move a dial indicator over the flywheel friction surface to measure the distortion.

For more accurate measurement, use a portable jack.

If the distortion is beyond the limit, regrind the friction surface.

NOTE: If the ring gear develops any unusual condition, replace it with a new one before taking a measurement.

(c) Correction of friction surface

Correct the friction surface with a surface grinder. Make sure that the friction surface is parallel to surface A within 0.1 mm.

NOTE: After correction, make sure that the height of the friction surface (dimension B) is within the limit.

(2) Reassembly

(a) Installing flywheel housing

Measure the installed state (eccentricity) at the spigot joint of the flywheel housing. If the dial gauge indicates runout exceeding the specified limit, loosen the bolts and tap the housing lightly to correct position.

(b) Installation of oversize oil seal

If an excessive amount of oil leaks from the oil seal, use the auxiliary oil seal and sleeve.

To install the sleeve, use Oil Seal and Sleeve Installer (special tool). The pressed position of the sleeve is determined where the flywheel is installed.

NOTE: Face the white painted side of sleeve, toward the crankcase.

(c) Installation of washer plate

Install the washer plate with its shear droop end facing toward oil seal side.

(d) Installation of flywheel

Mount the flywheel onto the crankshaft and tighten bolts to specification.

Measure runout (installed position) of the flywheel. If the dial indicator deflects over the limits, check bolts for looseness or mounting surface.

5-1-4 Timing Gear and Camshaft

(1) Disassembly

For disassemly of parts with an encircled number, see following items.

The parts marked with * must be inspected before disassembly.

(a) Removal of taper cone <D3, 6DR5>

To remove, use Cone Puller (special tool).

(b) If the crankshaft pulley flange and crankshaft pulley are hard to remove, use Gear Puller (special tool).

(c) Do not remove oil seal and seal plate unless abnormal condition is evident.

(d) Measurement of backlash

Measure the backlash between gears and replace if the limit is exceeded.

NOTE:

1. For a pair of gears, the backlash must be measured at three points or more to determine the condition.

2. When measuring the backlash in injection pump gears, keep the pump fixed onto the front plate.

(e) Measurement of end play

Measure the end play of the idler gear and camshaft with a thickness gauge or dial indicator. If the measurements exceed the limit, replace the parts.

(f) Removal of idler shaft <DR>

For removal, use Idler Shaft Puller (special tool).

NOTE: Do not remove the idler shaft unless defects are evident.

(g) Removal of camshaft gear

1) Accessing through the holes in camshaft gear, loosen the thrust plate attaching bolts. Then, remove the gear together with the camshaft.

NOTE: On DR, turn the crankcase upside down before removing the camshaft.

2) To remove, use Gear Puller (special tool).

NOTE:

1. Do not remove the gear unless defect is evident.

2. For removal, never attempt to tap the gear with a hammer.

(2) Inspection

(a) With the idler gear I.D. and idler shaft O.D., calculate the clearance. If the limit is exceeded, replace the bushing in the idler gear.

(b) Replacement of idler gear bushing

Using Idler Gear Bushing Puller (special tool), replace the idler gear bushing. See illustration for procedure.

NOTE:

1. When installing the bushing, align the oil hole in bushing with that in idler gear.

2. After installation, make sure that the bushing to idler shaft clearance is within nominal value. If the clearance is below specification, ream the bushing.

(c) Measure the lobe height and basic diameter of each cam. If the difference between them is below the limit, replace.

NOTE: Since the taper cam is used on D3, ensure that the measurement is taken at the location indicated in illustration.

(d) Measure the camshaft journal O.D. and crankcase I.D. If the limit is exceeded, replace the bushing in the crankcase.

(e) Replacement of camshaft bushing

1) Removal

Remove the sealing cap through the camshaft hole in the rear-end face of the crankcase. Then, using Camshaft Bushing Installer and Extractor (special tool), remove the camshaft bushing.

2) Installation

Identify bushings with a unique number stamped on the external surface, indicating the installation position.

Then, using Camshaft Bushing Installer and Extractor (special tool), press-fit the bushings.

If the marking is illegible, determine by measuring the I.D. and width.

(f) Measure the bend of camshaft. If the limit is exceeded, correct with a press or replace.

NOTE: Rotate the camshaft a turn and read the deflection of the dial indicator pointer. One half of the reading is the bend.

(g) Tappet to crankcase clearance <DR>

If the clearance exceeds the limit, replace the tappet.

(3) Reassembly

(a) Installation of camshaft gear

After mounting the thrust plate, install the camshaft gear with its number marking side facing outward.

(b) Check the camshaft end play. Then, install the camshaft into the crankcase.

NOTE: On DR, install the camshaft gear after installing tappet with the crankcase turned upside down.

(c) Installation of idler gear

Install the idler gear, its side with a number marking facing outward and its alignment mark lining up with others.

<D3>

Make also sure that the idler shaft spring pin rests in the crankcase oil groove and the "UP" mark with an arrow on the shaft faces upward.

< DR >

Install the idler shaft with its spring pin positioned as illustrated, and install idler gear with the metal layer of thrust plate on the gear end.

(d) Check gears for backlash.

(e) Apply lithium-base grease to the oil seal lips.

On 6DR5, align the timing gear case notch with that of seal plate.

5-1-5 Crankcase and Main Moving Parts

(1) Disassembly

For disassembly of parts with an encircled number, see following items.

The parts marked with * must be inspected before disassembly.

(a) Piston projection

Incorrect piston projection adversely affects the engine performance. If measurements are out of specification, check parts for clearance.

1) Hold the dial indicator on the crankcase top surface to make zero adjustment.

2) Locate the piston TDC with the dial indicator.

3) Measure projections at three points on the piston top surface to obtain the average value.

(b) Connecting rod end play

Measure the end play of each connecting rod. If the limit is exceeded, replace the connecting rod.

(c) Removal of piston

Withdraw the piston from the crankcase, pushing it up together with the connecting rod.

NOTE:

1. If the piston pin is hard to remove, heat the piston with a piston heater or hot water.

2. Do not remove the connecting rod bolts from the connecting rod unless defective. If the bolt is damaged, install a new connecting rod bolt by referring to "5-1-5", (3)(e)".

(d) Removal of piston ring

To remove the piston rings, use Piston Ring Tool (special tool).

(e) Crankshaft end play

If the end play exceeds the limit, replace the thrust plate with an oversize.

Three oversize thrust plates are available: +0.15, +0.30, and +0.45 mm

NOTE: The thrust plates on both ends of the bearing cap need not be of the same size; however, use the one of the same size for those at the rear end of the crankcase and in rear of the bearing cap.

(f) Removal of main bearing cap

To remove the main bearing cap, use Bearing Cap Extractor (special tool).

1) At front and rear ends

2) Intermediate position

(g) Removal of crankshaft gear

To remove the crankshaft gear, use Gear Puller (special tool).

NOTE: It is not necessary to remove the crankshaft gear unless defect is evident.

(2) Inspection

(a) Measurement of cylinder sleeve I.D.

Measure the cylinder sleeve I.D. at the six points shown in illustration.

If the I.D. exceeds the limit, replace or bore to oversize.

If the cylinder sleeve is to be used without being bored, correct the ring ridge wear at its top by grinding with a ridge reamer.

(b) Replacement of cylinder sleeve

1) Removal

a) With a boring machine fixed in the crankcase, center the machine. Make sure that the machine is centered at the bottom of the cylinder sleeve which develops uneven wear least.

b) Bore until the wall thickness is reduced down to approximately 0.5 mm.

c) Insert a screwdriver (machined as illustrated) between the crankcase and cylinder sleeve. Tap the screwdriver to break and remove the sleeve.

Make sure that the rounded part of the screwdriver faces to the case.

2) Installation

After the cylinder sleeve has been removed, check the crankcase sleeve hole for damage and proper interference.

If defects are evident, bore the crankcase sleeve hole.

For measurement of interference, measure the cylinder sleeve O.D. and crankcase sleeve hole I.D. at the positions indicated in illustration. Calculate the average value of the measurements in the vertical (D₁, D₂, D₃ ) and diametrical (A, B) directions.

If the interference exceeds the limit, bore the crankcase sleeve hole to oversize.

* When crankcase sleeve hole interference is sufficient:

a) Using Cylinder Sleeve Installer (special tool) and a hydraulic press (sleeve installation load: 4.7 to 9 t), install the STD cylinder sleeve into the crankcase. During installation, ensure that the chamfered side of the sleeve faces down and the sleeve top surface is flush with the crankcase top surface.

b) After installing the cylinder sleeve, obtain the nominal dimension for I.D. and finish to 3.2-S by honing operation.

* When crankcase sleeve hole interference is insufficient:

a) Ready an oversize cylinder sleeve with a 0.5 mm larger O.D Hone the crankcase sleeve hole to 8S to obtain the nominal value for the interference between the cylinder sleeve O.D. and crankcase sleeve hole.

b) Using Cylinder Sleeve Installer (special tool), install the cylinder sleeve into the crankcase. After installation, obtain the nominal value for the cylinder sleeve I.D. and hone the surface to 3.2-S.

NOTE:

1. When boring the crankcase sleeve hole, remove sleeves from all cylinders and bore to roundness.

2. Before installing the sleeve, apply spindle oil (MECHANIC #32 or equivalent) to the crankcase sleeve hole.

(c) Selection of oversize

Available oversizes (4 types): +0.25, +0.5, +0.75, +1.00 mm

1) An oversize must be determined in consideration of the part developing the most serious wear from all cylinder I.D. measurements.

2) Using a micrometer, measure the O.D. of individual oversize pistons to be used.

3) Bore and hone the cylinder sleeve to obtain the nominal value for the cylinder sleeve to piston clearance.

NOTE:

1. Even if only one cylinder requires boring, make sure that all cylinders are bored to the same oversize.

2. Replace the piston and the piston rings with the corresponding oversizes.

(d) Crankcase top surface distortion

If the limit is exceeded, correct with a surface grinder.

NOTE: Crankcase must be ground only to the extent that the piston projection does not exceed the nominal value.

(e) Piston O.D.

Measure the piston skirt O.D. and calculate the clearance with the smallest cylinder sleeve I.D. measurement [See (a)]. If the limit is exceeded, replace the cylinder sleeve or piston.

NOTE: If a piston is replaced, replace also the piston ring.

(f) Piston to piston ring clearance

If the limit is exceeded, replace the piston ring or piston.

NOTE:

1. Remove carbon and measure the clearance throughout the entire periphery of the piston.

2. Replace piston rings as a set.

For the 1st compression ring, press the ring against the piston with a straightedge.

(g) Piston ring gap

Put the piston ring in the standard gauge or crankcase cylinder sleeve by pushing it with piston and measure the ring gap.

If the limit is exceeded, replace.

Standard I.D.:

100 ± 0 <D3>

92 ± 0 <DR>

(h) Piston to piston pin clearance

If the limit is exceeded, replace the piston pin or piston.

(i) Piston pin to connecting rod clearance

If the limit is exceeded, replace the connecting rod bushing.

(j) Replacement of connecting rod bushing

1) Removal of bushing

Using Connecting Rod Bushing Puller or Connecting Rod Bushing Puller Kit (special tool), remove the bushing.

<4D31-T>

a) With the connecting rod bearing removed from the connecting rod big end, secure the connecting rod to Base (special tool).

b) Set Mandrel and Collar A (special tools) onto the connecting rod small end as illustrated at right and gradually apply force with a press.

2) Installation of bushing

< Except 4D31-T >

a) Insert the bushing into Connecting Rod Bushing Puller (special tool).

b) Apply engine oil to the bushing and connecting rod.

c) Press-fit the bushing into the connecting rod.

NOTE:

1. Press the bushing into the chamfered end of the connecting rod.

2. Align the oil hole in the bushing with that in the connecting hole.

3. After the piston pin has been inserted, make surface that there is no excessive play and it turns smoothly.

< 4D31-T >

a) Set the bushing to Mandrel, Collar B, Collar A, and Nut (special tools).

b) Apply engine oil to the connecting rod small end and bushing.

c) press the special tools, to which the bushing is set, into the connecting rod small end with a press.

d) After the bushing is pressed into position and special tools are removed, ream the bushing to obtain the specified bushing to piston pin clearance.

NOTE:

1. When installing the bushing, make sure that the oil hole in bushing is aligned with that in the connecting rod.

2. When the piston pin has been installed, ensure that it turns smoothly with no excessive play.

(k) Bend and twist of connecting rod

Measure with Connecting Rod Aligner (special tool). If the limit is exceeded, replace or correct with a press.

NOTE:

1. Measure with the bushing and connecting rod bearing installed in the connecting rod.

2. The connecting rod and connecting rod cap bolts must also be tightened to specification in measuring.

(1) Connecting rod bearing tension

Measure the tension of the connecting rod bearing when free and, if the measurement falls short of the limit, replace the upper and lower bearings as a set.

NOTE: Never attempt to expand the bearings for reuse.

(m) Connecting rod bearing to crankshaft clearance

If the limit is exceeded, replace the upper and lower connecting rod bearings as a set.

(n) Main bearing to crankshaft clearance

If the limit is exceeded, replace the upper and lower main bearings as a set.

(o) Main bearing tension

Measure the tension of the main bearings when free. If the measurements are below the limit, replace the upper and lower main bearings as a set.

NOTE: Never attempt to expand the bearings for reuse.

(p) Roundness and cylindricity of crankshaft

Determine roundness and cylindricity of the crankshaft based on measurements of journal and pin O.D.s. If the limit is exceeded, grind to undersize.

(q) Crankshaft bend

If the limit is exceeded, correct with a press or grind to undersize.

If the bend is excessive, replace.

NOTE: Read the crankshaft center journal runout with a dial indicator. One half of the reading is the bend.

(r) Correction of crankshaft to undersize

If a journal or pin is damaged or seized, grind the crankshaft by using the following procedures.

Replace the bearing with an undersize.

1) During grinding, use care not to change the center distance of journal and pin.

2) Use care also not to change the width of journal and pin.

3) Finish the fillet smooth to the specified radius.

4) Check for grinding cracks by the magnetic particle inspection method. Make also sure that the surface hardness (shore hardness Hs 75 or more) has not decreased.

5) When grinding the crankshaft with a grinder, the grinder and crankshaft must be turned counterclockwise as viewed from the crankshaft front end.

6) To finish the crankshaft with a grindstone or sandpaper, turn the crankshaft clockwise.

Crankshaft Undersize Dimensions

(3) Reassembly

(a) Install the thrust plate and upper main bearing to the crankcase.

NOTE:

1. Install the thrust plate with its side having no oil groove toward the crankcase.

2. Line up the lug of main bearing with the lug groove in crankcase. Note that the upper main bearing has an oil hole, which must not be confused with the lower.

3. Apply engine oil to all sliding surfaces.

(b) Installation of crankshaft gear

When the crankshaft gear was removed, it must be heated with a piston heater or similar device before being reinstalled onto the crankshaft.

(c) Installation of main bearing cap

1) Fit the lower main bearing into the main bearing cap. At the time, make sure that the main bearing lug is aligned with the main bearing cap lug groove.

2) Install also the thrust plate onto the main bearing cap in the rear-end position.

3) Make sure that the main bearing cap lug groove and crankcase lug groove are on the same side. Ensure also that the embossed numbers on main bearing caps are in ascending order from the front of engine.

NOTE:

1. Face the side of thrust plate having no oil groove toward the main bearing cap.

2. Use thrust plates of the same size for the crankcase and main bearing cap rear end.

3. Apply sealant to the crankcase front and rear surfaces onto which bearing caps are mounted.

4) Tighten the main bearing cap bolt to specification.

Then, make sure that the crankshaft turns smoothly by hand.

5) Measure the crankshaft end play to determine if it is within the nominal value [See 5-1-5 (1), (e)].

(d) Installation of side seal

Install the side seal with sealant applied to its end. Then, apply sealant to the bearing cap.

NOTE: When installing the side seal, ensure the correct installation direction.

(e) Reaseembly of piston and connecting rod

1) Assemble the piston and the connecting rod, ensuring correct direction as illustrated.

2) Insert the piston pin to couple the piston and connecting rod. Mount the snap ring to hold the piston pin in position. The piston pin is a clearance fit in the piston. If the piston pin is hard to fit, heat the piston with a piston heater or hot water.

NOTE:

1. The parts for an engine must be of the same weight mark.

2. Apply engine oil to all sliding surface.

3) The connecting rod bolts do not normally need removal; however, where replacement is necessary for damaged bolt, install new bolts by using the following procedures.

Make sure that the connecting rod bolt hole is free from damage and burrs. Then, with engine oil applied to the connecting rod bolt, press it into position with a press. (Pressing load: Max. 4.9 kN or 500 kgf)

(f) Installation of piston rings

To install piston rings, use Piston Ring Tool (special tool).

NOTE: A manufacturer's mark is stamped near the piston ring ends. Install with the mark up.

Direct the open ends of piston ring as shown.

(g) Installation of piston and connecting rod assembly

Fit the upper connecting rod bearing into the connecting rod and install the piston into the crankcase with Piston Guide (special tool).

NOTE:

1. Face the position mark on the lug end toward front of engine.

2. Make sure that the piston ring ends position does not change during installation.

3. Cover the connecting rod bolt with a vinyl hose so as not to damage to crankshaft pins.

Use of Piston Guide <D3>

With the Piston Guide lined up with the piston skirt, set the lever in position and adjust with the adjusting bolt to match the clamp I.D. with piston O.D.

On completion of adjustment, remove the Piston Guide from piston and apply engine oil to piston external surfaces, Piston Guide internal surfaces, and cylinder liner internal surfaces.

After these procedures have been completed, install Piston Guide to the piston with their top surfaces flush with each other and tap piston top with a mallet or other soft object into position so as not to damage to the piston.

(h) Fit the lower connecting rod bearing to the connecting rod cap and tighten the connecting rod to specification.

NOTE: The lug sides of the connecting rod and connecting rod cap must be in the same direction.

(i) Check the connecting rod end play [See 5-1-5 (1), (b)].

(j) Check piston for projection [See 5-1-5 (1), (a)].

5-1-6 Inspection and Adjustment of Valve Clearance

Inspect and adjust the valve clearance when the engine is cold by using the following procedures.

(1) Crank the engine with Cranking Handle (special tool) to line up the inscribed line "0" position on the "1.4" stamped side of the crankshaft pulley (4DR5; the inscribed line "0" position on crankshaft pulley. 6DR5; the inscribed line "1.6" position on the flywheel) with the pointer.

Another pointer is provided on the crankshaft pulley top <4D3>. If this pointer is used, use the inscribed line "0" position on the "2.3" marking side of the crankshaft pulley.

(2) When the piston in No. 1 cylinder is at TDC on the compression stroke (the push rods of No.1 cylinder not pushing up the intake and exhaust valves), check and adjust clearances of valves marked with "o" in the following Table. Then, with the crankshaft rotated a turn, check and adjust clearances of the remaining valves marked with "x".

If the No.4 or No.6 cylinder piston is at TDC on the compression stroke (push rods in the No.4 or No.6 cylinder not pushing up the intake and exhaust valves), similarly check and adjust the clearances of valves marked with "x" first; then, turn the crankshaft a turn, check and adjust valves marked with "o".

(3) Insert the specified thickness gauge between the rocker and valve cap to check for clearance.

If the valve clearance is out of the nominal value, loosen the lock nut and turn the adjusting screw to the extent that the thickness gauge moves slightly tight.