K.Y. Marine Engineering Ltd






General Precautions
Cylinder head

Fuel oil pipe
Fuel Nozzle
Exhaust valve
Intake valve
Valve clearance
Starting air valve
Piston overhaul
Connecting rod
Crankpin bearing
Cylinder liner
Sole plate
Main bearing
Thrust bearing
Crank shaft
Timing gear
Cam shaft & Cam
Adjustment of cam
Fuel Injection system
Fuel oil system
Cooling water system































































































































































































































































































































































































































































































































































General Precaution 

General Precautions for Disassembly, Assembly and Adjustment Prior to disassembly, assembly and/or adjustment of engine, the engine internal construction and standard adjustment procedures should be fully understood, and the standard maintenance procedures to be described herein read thoroughly.

1. Handle the engine and other parts carefully.
safety first should always be your slogan.
2. Give heed to the assembly sequence and tally marks to avoid mis-assembly.
3. When disassembling jointed parts, pay special attention to the match marks.  If the match marks are not provides or are blurred, mark them clearly. When overhauling parts associated with specific cylinder numbers mark them with paint or magic pen so that can be clearly identified in assembly.
4. Each disassembled part should be put in a designated box or the like container in good order or kept nearly in designated places to avoid misplacement.
5. Do not mix the special heat-resistant bolts and nuts used with the exhaust pipe, etc. (exposed to high temperature) with other kinds of bolts and nuts in assembly.
6. Tighten bolts and nuts with force observing the correct tightening torques, as specified each engines.
7. Check periodically for looseness of bolts and nuts for internal components which are not overhauled.
8. If turning is necessary midways in disassembly or assembly, ensure that there are no parts that may come into contact with the rotary part and that there is no danger to the personnel working nearly.
9. Use standard tools when disassembling and assembling the engine.
10. When disassembling, take specified measurements at as many points as possible; data thus gained should be filed for later reference.
11. Packings should be replaced at each disassembly. So a sufficient number of packings should be a hand to match the degree of disassembly.
12. When some spare parts are used, replenish them at once.
13. From the viewpoint of full utilization of engine performance, with appropriate periodic overhauling intervals, and of the interchange ability and accuracy of the parts used.
14. Cover each of disassembled parts without fail to keep out dust.
15. Before assembling, make sure that all parts are clean. If any are soiled, wash with gas oil, or airblow clean.

Cylinder Head

Overhauling process
1. Remove cylinder head top cover.
2. Disconnect all piping around cylinder head.
3. Remove rocker arm shaft holder.
4. Disconnect high pressure fuel pipe.
5. Remove cylinder head lower cover
6. Remove push rod and protective sheath.
7. Remove cooling water regulating cock.
8. Remove nozzle holder
9. Unscrew exhaust pipe fixing bolts.
10. Unscrew intake air pipe fixing bolts.
11. Remove indicator valve
12. Remove cylinder head tightening nuts.
13. Remove cylinder head.

1. When detaching cylinder head, take care not to Damage fit-up surface of o-ring fitted to cooling water guide.
2. Before scraping carbon deposits from combustion chamber, check deposit condition and quality.
3. Remove carbon deposits from combustion chamber and carefully check for cracks.
4. Since cylinder head packing has the important function of sealing high pressure gas, always replace it, insofar as possible , at each overhaul.
Since cylinder head packing seat section is susceptible to flaws give special care to handling.
5. Check for corrosion on fit-up surface of o-ring for cooling water guide, and also for gas leakage through cylinder head packing.  Minor corrosion or gas leakage should be corrected at once.
6. Check and remove fur accumulated on water jacket of cylinder head at least once every two years. If not cleaned for a long time, cooling efficiency drops, water passage is clogged and cracks may develop.
7. Upper surface of cylinder head serves as return passage for rocker arm lubricating oil. Clean this surface with care so that foreign matter such as dust or cotton waste, etc. does not enter lubricating oil.
8. When lifting cylinder head, life it horizontally. Take care not to allow water inside jacket to enter cylinder.
9. Loosen cylinder head fixing nuts gradually the sequence shown below, so that all are loosened completely after second run. Loosening each one fully at once will exert undue strain on other bolts still tightened firmly. Proceed in the same manner also when tightening to fix cylinder head.
10. When loosening cylinder head tightening nuts, use a box spanner. Use torque wrench only for tightening.
Take special care in setting cylinder head so as not to scratch or dent packing surface of cylinder head or liner or fixing nut. Clean thoroughly to remove dust, etc. before fixing.
Tighten intake/exhaust pipe fixing bolts prior to tightening cylinder head fixing nuts. Cylinder head adjust intake/exhaust pipe flange face to face.

High pressure fuel oil pipe

When connecting high pressure fuel oil pipe to nozzle holder or disconnecting it,  use double spanners so no torque will be exerted on inlet connector.
High pressure fuel oil pipe should be handled with good care as it is subject to very high pressure.  Special care should be taken not to scratch the fit-up surface of each fitting and joint.
Disassembly procedure>
1. Remove o-ring guide set bolts
2. Displace o-ring guide toward holder side.
3. Using special spanner provided, remove cap nut at holder side.
4. Displace tube retainer upward.
5. Loosen cap nut at pump side.
6. Rotate nozzle holder sideways and detach fitting to high pressure pipe from nozzle holder.
7. Extract nozzle holder.

Fuel nozzle

Since maintenance of the nozzle has a great effect on the condition of combustion and output, be sure to disassemble and inspect it whenever any change in exhaust gas temperature or color is noted.
Be sure to use the nozzle specified on the factory operation data sheets.
Before removing nozzle, check condition and quality of carbon deposits.
Nozzle injection testing>
1. Detach the high pressure fuel oil injection pipe and other piping , and remove nozzle from cylinder head using nozzle holder disassembly tool.
2. Before removing nozzle, measure and record nozzle injection pressure.
3. Remove pressure adjustment bolt cover of nozzle holder, loosen pressure adjustment bolt.
4. After removing carbon deposits, detach nozzle from holder.
5. Clean carbon from nozzle tip.
6. Attach nozzl eot nozzle testeras specified on assembly.
1. Operate the nozzle tester hand lever at as stroke of 46 time per second and check the spray mist to see that it is uniform without abnormality due to the blocked injection hole.  Shown below are different condition of fuel spraying through injection nozzle.
2. When removing nozzle, be sure to loosen nozzle holder pressure adjustment bolt.  When remounting, pressure adjustment bolt should be loose. Nozzle removal/remounting with pressure adjustment bolt tightened may damage needle and cause mal-injection.
3. In nozzle testing, check carefully also for wear or corrosion of needle valve, and replace it if worn.  Special care should be taken as to injection port wear, which is likely to occur when heavy fuel oil is used.
4. Check for smooth movement of nozzle and needle; replace if either is stuck.
5.  Do not fit nozzle and needle with lapping agent.
6.  Nozzle and needle are used as a pair;
do not intermix pairs.
After cleaning nozzle and needle of carbon, wash in clean gas oil and air-dry.
7. Before fitting tested nozzle to nozzle holder, clean mating faces thoroughly to remove dust or other foreign matter; then tighten with correct torque as specified in the Tightening Torque Table shown in each engine instruction book. Tightening with excessive torque may result in sticking of needle valve.
8. Since the high pressure fuel injection pipe is subject to very high pressure during operation, install it without imposing any stress.   Check occasionally for loosening of joints of high pressure fuel injection pipe and other piping as it may cause leakage of oil into rocker arm lubricating oil.

Exhaust valve

1. Exhaust valve seat is pressure-fitted into cylinder head. Therefore, exhaust valve should be fit with cylinder head overhauled.
2. Exhaust valve fitting is the most complicated maintenance task.  Although the interval of maintenance varies depending upon load ratio, combustion condition, fuel oil grade, etc., it is advisable to conduct the first round maintenance as early as possible and then to prolong the interval according to the circumstances.
3. Measure clearance between valve stem and valve guide at the time of inspection of extracted valve. Excessive clearance may result in gas leakage or breakage of valve spring.  Replace valve stem or valve guide, whichever is worn more.
4. For fitting valve, first coat with proper amount of fitting agent and fit using intake and exhaust valve fitting tool. Use Medium to Fine fitting agent. Then, wash the valve well and perform final fitting with machine oil. Since exhaust valve and valve seat are very hard because of stellite reinforcement, it is desirous to use grinding for dressing the fit-up face.  Valve should be fit with bet care, sparing enough time for obtaining good fit.
5. If valve seat is worn excessively, dress the seat face by either machining or with grinding tool.  Grinding tool is optionally available.
When repairing either exhaust valve or exhaust valve seat, finish the seat portion to the angle as shown below, so that the valve will be seated harder at the combustion chamber side.
6. Frequent fitting of valve or frequent machining tends to widen the seat width. When the valve has worn beyond the allowable wear limit, replace it with newone.
Machining of back side of valve is prohibited as it lowers the valve strength.

<Disassembly procedure>
1. Set intake/exhaust valve extraction tool to the nozzle holder guide hole on top of cylinder head.
2. Holding the spring by turning the bolt, extract cotters.

1. Valve spring cotters are manufactured as a pair.  In disassembly and assembly, be sure to keep them together and use them on the same valve.
2. Check valve spring for cracks with color penetrant.
3. Check valve rotator.
4. When assembling, do not forget to insert valve retaining ring into groove on valve stem.

<Check items>
1. High temperature corrosion of valve head.
2. Sulfuric acid corrosion or bend at valve stem.
3. Blow-by or pitting at valve seat
4. Fit-up at valve seat
5. Fit-up at valve stem end
6. Valve spring caking or corrosion (check via color penetrant test as necessary)

Intake valve

1. Intake valve seat is pressure-fit into cylinder head.  This part should be fitted when overhauling cylinder head.
2. When clearance between valve stem exceeds the allowable wear limit, replace stem or guide, whichever is worn more.
3. When valve seat exceeds specified repair limit after machining or due to wear, replace it with new one.
4. Fitting of intake valve and valve seat.
a) Intake valve and valve seat should be fitted carefully, as with exhaust valve. Wash it well and perform final fitting with machine oil.
b) Heavy scratching or dents on face or seat portion of intake valve should be rough dressed by machining or with valve seat cutting tool.  Do not forget to fit after dressing.
  When repairing either intake valve or intake valve seat, finish the seat portion to the angle as shown each engine instruction guide, so that the valve will be seated harder at the combustion chamber side.

Adjustment of valve clearance

clearance at valve end is too small, valve stem and push rod will by heat during operation causing improper valve seating, which may result in damage to valve or improper combustion.
too large a clearance may cause an increased level of noise in operation or damage or abnormal wear in the valve operating mechanism.
Therefore, maintaining the right amount of clearance is essential for normal operation.
Valve operating mechanism in the engine presses two intake valves (or exhaust valves/or one and one) simultaneously with one T-shaped yoke.
If the heights of these two valves fail to agree precisely, imbalance in the valve pushing force will cause valve or valve holder to fall, leading to abnormal valve guide wear or valve damage. To avoid this, adjust valve end clearance in the following procedure after valve maintenance.
(Follow up each engine maker's instruction)

<Measurement of valve end clearance>
1. Bring intake and exhaust valves for cylinder to be measured to fully closed positions. (At this position, graduation marked on flywheel points to TOP position , with the marked line on the fuel injection pump at the up position.)
2. Loosen lock nuts and unscrew clearance adjusting screw 1 and 2.
3. With valves contacting firm at end A, adjust with screw 1 so that the other end fits closely at B.
4. With adjusting screw 1 held securely via spanner applied to the square head, tighten lock nut firmly.
5. Insert a feeler gauge of the specified thickness at part C and adjust screw 2 in the same manner as for screw 1.          

Starting air valve

If the starting air valve fitting is improper or the valve rod or the starting air valve piston becomes struck, gas counter flows into the main starting air pipe, causing sticking of the starting rotary valve and starting air valve and thereby damaging them. For this reason , it is necessary to perform the fitting work with care.
Operational overheating of starting air pipe is caused by gas leakage from starting air valve. Check valve at once and stop leakage.
It is recommended that starting air valve fitting be done together with the intake valve.

1. Remove starting air valve piston case.
2. Remove split pin for tightening nut of starting air valve spring seat and remove nut.
3. Remove starting air valve spring seat and spring.
4. Pull out starting air valve rod to combustion chamber side.
1. Do not tighten tightening nut of starting air valve seat with excessive force,  otherwise, screw parts of valve rod may be broken and valve rod drop during operation.
2. Divide split pin carefully, making sure that it does not touch starting air valve piston.

Piston overhaul

Piston overhaul intervals differ according to the degree of daily maintenance, especially to the control of lubricating oil.  Since appropriate overhauling interval varies with the individual engines, it is to be decided by the judgement of the person in charge of the engine.
It is recommended that an optimum schedule be arranged by match the individual conditions using the maintenance intervals shown on each engine instruction of makers.
Interval can also be judge by the amount of lubricating oil consumption. As lubricating oil deteriorates its consumption increase due to sticking in rings and increased blow-by.
If consumption is double the normal level, overhaul must be considered, with replacement of rings as necessary.

<Piston extraction procedure>
1. Remove carbon accumulated in the combustion chamber at the upper part of cylinder liner.
2. Remove set bolt for connecting rod lock washer and take out washer.
3. Set crank pin at 2030 past top dead center in the crank normal rotation direction and pull out connecting rod bolt.
4. Remove connecting rod cap.
5. Attach piston lifting ring to top of piston and lift it up.
6. Place piston at designated place. After removing piston pin retaining ring, extract piston pin while holding the connecting rod.
Piston assembly procedure>
1. Set piston pin and connecting rod.
2. Insert piston pin retaining ring in the groove.
3. Fit piston insertion frame to the upper part of liner.
4. Attach piston lifting ring to top of piston and lift it up.
5. Set crank pin at the same position as for disassembly, and insert piston slowly into the liner using the piston insertion frame as a guide.
6. Fit connecting rod cap from beneath; tighten connecting rod bolt to specified torque and fit lock washer.
1. When loosening connecting rod bolt, use a spanner.  Do not use a torque wrench for this purpose.
2. Be sure to use a torque wrench when tightening connecting rod bolt and tighten correctly referring to Tightening Torque Table shown on each engine instructions.
2. Since carbon is likely to deposit in hole for piston lifting ring, be sure that the ring is screwed in firmly.  It may be advisable to clear threads with a tapping tool beforehand.
3. When extracting and replacing piston , take care not to damage crank pin bearing and serrated section of connecting rod.
4. Be careful not to damage crank inner surface of liner with the large end of connecting rod.
5. Before inserting piston in the liner , lubricate all the sliding parts ( outer surface of piston, liner and bearing) with lubricating oil. Except for the back face of bearing.
6. Be sure to align match marks of connecting rod and cap when assembling.
7. When extracting piston , be careful not to allow connecting rod to contact piston cooling system.
8. Take care not to damage crank pin with serrated portion of connecting rod.
9. When positioning piston,
be sure not to confuse intake (I) and exhaust valve sides (E).
10. With incorrect positioning, intake valve will strike upper part of piston, potentially leading to a serious accident.
11. When inserting piston into liner, tap periphery lightly piston with a plastic hammer or the like. If it cannot be inserted smoothly, do not force it; lift piston temporarily and re-insert.
12. Thoroughly remove carbon deposits from piston and liner.

1. When extracting piston, carefully check carbon deposit and condition of lubricating oil drip and record the findings for reference for use during later maintenance.
2. Check for any abnormal contact marks on the piston or seizing in rings.
3. Check the condition of scale deposit inside the piston from back side.
4. Check at piston cooling oil inlet for contract marks caused by interference with nozzle.
5. Check for any abnormal contact marks on piston pin and pin boss parts.
6. Scale off carbon deposit on the piston thoroughly. After washing, measure dimensions of all the parts.  Use fine grain sand to scale off carbon deposit, except for the piston skirt part; avoid use of sand paper here, which would damage special coating. (When FCD piston is used)

Piston ring
1. If Piston ring is consisting with chrome plated, check the plated layer is abraded or not, the abraded ring should be replaced with a new one.
2. At the time of periodic overhaul of piston , replace the rings in consideration of the length of operating time until the next overhaul.
3. Measure each part after removing carbon and oil completely.
4. Since oil ring quality affects lubricating oil consumption, special care should be taken in this regards.
a) After a long period of operation, circumference of each ring will have become sharp edged.  Therefore. Be careful in handling them and wear gloves during overhaul.
b) When mounting ring, place the marked side up (toward the combustion chamber), and set in the correct order.

Connecting rod

1. Check serrated mating surface at large end of connecting rod for cracks or wear.
2. Check if piston pin bearing at small end fits firmly in position with proper fit-up.
3. Measure bore of bearing and outside diameter of piston pin and check that dimensions are within allowable wear limit specified each engine instruction. When replacing piston pin bearing worn beyond the allowable wear limit, remove it with a press or by driving it out, confirm position of the oil hole on new bearing and press it in.
4. When too large a load is applied to the engine as a results of piston seizure or water hammer, connecting rod may have bent or fallen. Accordingly, at overhaul, connecting rod should be thoroughly examined for cracks by color check. However, such checking is not required at periodic overhaul.

Crank pin bearing

1. When detaching crank pin bearing from connecting rod, lightly tap notch side of back shell with a piece of wood to create a gap between shell and bearing housing for easier removal.
2. Check condition of crank pin bearing with care and measure how much it has abraded.
3. To ensure that crank pin bearing maintains close contact with surface of  housing, crank pin bearing shell must have proper crush and tension. Refrain from using files or scrapers at any time.
4. If crank pin bearing must be replaced,
replace upper and lower shells at same time.
5. On assembling crank pin bearing, thoroughly wipe dust or other foreign matter from housing and shell back face.  Refrain from applying any grease or lubricating oil to back face of shell. Align notches so that direction of bearing will not by mistaken. Tap center part of bearing by hand a few times to fit it with housing.
6. Even if bearing abrasion is still within the allowable limit, if it is used for a long time, it loses tension. Which may cause cracks. Therefore, it is better to replace it with a new one after 4 years or so of operation.
7. If bearing check is required while engine is stopped, disassemble and check bearing by lifting piston via piston supporting tool.
a) Bring piston in cylinder to top dead center.
b) Detach nozzle holder from cylinder head.
c) Insert piston supporting ring into hole on nozzle holder and screw it into threaded hole provided at the upper rod bolt, remove cap at large end and disassemble bearing for inspection.
d) Loosening connecting rod bolt, remove cap at large end and disassemble bearing for inspection.

Tightening of connecting rod bolt
Be sure to tighten connecting rod bolts firmly.
Poor tightening may result in damage to bearing metal or serrated portion at large end, or to a catastrophic accident such as bolt breakage.
1. Handle parts carefully so as not cause scratches, dent or deposition of dirt on screw portion of bolts and connecting rod contract surface.
2. Roughening or scratching on bolt threads or seat surface may result in poor tightening ;to ensure firm tightening , spray anti-seizure agent (MOLYKOTE 1000 spray type) Over these surfaces.
Roughness or scratches on surface, if any, should be repaired by machining or otherwise.
3. Screw the bolt into the original hole from which it was removed.
4. At first screw bolts by hand and check without any resistance.
Tighten bolts as following procedure
a) First confirm the match marks punched at (A) and (B) on large-end cap shown below.
b) Attach large-end cap without bearing metal; using a torque wrench, tighten bolts to torque A (follow as specified each engine)
Tightening sequence;
 Bolt - Bolt - Bolt
c) Punch tally mark on bolt heads to match with (A) marks on large-end cap.
d) Attach bearing metal and install in engine. Tighten bolts with torque wrench of the specified capacity. Be sure to tighten them by two steps.
Tightening sequence;
1 st step : At torque A
Bolt - Bolt - Bolt
2 nd step : At mark B
Bolt - Bolt - Bolt
1. Anti-seizure (MOLYKOTE 1000 Spray type) should be used to bolt seats and threads before tightening.
2. At connecting rod bolts, A torque and rotation angle should be the first concern, B torque is for reference only.
e) After tightening to mark B, check tally marks on bolts coming to B position on lock washer in place.
After long term operation, each parts become running-in condition, resulting in some deflection of the relative positions of bolt and large end cap.
Therefore, bolt tally marks cannot be reused after extended operation; punch new marks. When tightening bolts to new marks, distinguish new marks from conventional marks.

6. After installation, check side motion of connecting rod without fail to secure the appropriate clearance between rod metal and shaft. After test running, thoroughly check, by hand touching, that there is no abnormality; and then start normal operation.

Cylinder liner

1. Wear of cylinder liner bore differs according to fuel oil grade, control condition of lubricating oil and temperature of cooling water , etc.  As progress of wear leads to such problems as blow-by, increased lubricating oil consumption, etc., cylinder liner worn beyond the allowable limit as specified each engine, should be replaced with a new one at an early stage.  Because of initial wear , a newly built engine generally shows slightly more wear in its cylinder liner at this time than at other stages.
2. Remove carbon deposited on cylinder liner when overhauling and inspect and measure each part with care.
 Set liner wear locating deposited in the axial direction and the normal rotation direction.  Measure wear by cylinder bore gauge.
3. If air is mixed in cooling water, cavitation may occur in the liner jacket, and the liner may be corroded from its exterior. Therefore, desecrate fully, take out liner at least once every four years to remove fur collected in jacket, and carefully check extent of corrosion.
Check items>
1. Scratches, corrosion, scuffing, or cracks on sliding surface.
2. Removal of carbon deposits from upper inner side of liner (Check of jacket side of liner)
3. Cracks on flange fillet (Use color penetrant test)
4. Traces of erosion by cavitation. Minor erosion may be touched up with Devcon etc.
5. Corrosion or fretting at upper and lower parts of liner, where it is fit to engine frame.
6. Removal of deposits on jacket side of liner, excepting thin film of rust-preventive agent (greyish-brown)
7. Cracking where liner is fit to engine frame (color penetrant test). Peeled rust preventive coating on water jacket in engine frame should be repainted.
Extraction and insertion>
1. Cylinder liner is extracted and inserted using cylinder liner extraction tool as follows.
2. Align marks on liner and engine frame when inserting new liner.
3. When reassembling, replace upper packing, liner rubber ring and o-ring.
4. Since liner rubber ring and o-ring are watertight to seal between lower part of jacket and crankcase, take special care in fitting so as not to break them. Apply silicone rubber to prevent possible corrosion at the clearance.  However, do not apply silicone rubber to o-ring.

Piston cooling unit
1. Piston cooling nozzle is mounted at the lower part of engine frame. This part should not be disassembled unless absolutely necessary.
2. Piston cooling support is assembled with two knock pins.  After overhauling piston , bring the piston to bottom dead center as illustrated below and check for correct alignment with counterpart on piston using nozzle locating jig.

Sole Plate, Crankshaft and Related Parts

Sole Plate
1. When inspecting main bearing, check for proper fit at spigot-joint part and mating surface, and for scratches or cracks on these surface, including check of main bearing cap.
2. Check for loose main bearing bolts, and re-torque if any bolt has become loose in operation.
3. If excessive load was applied to main bearing or if crankshaft is burnt measure dimension of hole on main bearing. Check also for cracks or other damage on sole plate around main bearing.
4. When main bearing cap is disassembled for inspection of metal and reassembled, be sure to set it in proper direction.

Main bearing metal

1) Since main bearing metal is thin-shell type as crank pin bearing, no shim should be inserted between sole plate and bearing metal and no file or scraper should be used.
2) Since larger clearance may result in cracking, seizure or lubricating oil pressure drop, periodic overhaul is required. Otherwise, bearing metal wear causes increased crank deflection, bringing about a dangerous crankshaft condition due to the application of repetitious stress by internal moment.
3) Carefully check back side of bearing metal and mating surface for fretting, traces of seizure of buildup of foreign matter; measure degree of wear.
<Bearing metal clearance measurement>
1. Metal thickness measurement
Extract bearing metal and measure thickness.
2. Measurement by means of lead wire
Extract main bearing cap and put a soft lead wire (0.5mm) on upper part of crankshaft.
Then replace cap and tighten to prescribed torque. Remove cap and measure with a micrometer the thickness of the lead wire thus pressed.
3. Measurement with bridge gauge
Apply bridge gauge across crank journal and measure clearance between gauge and circumference of journal. An optional bridge gauge is available.
4. Measurement of outside diameter of crankshaft and inside diameter of metal
Remove crankshaft from sole plate and measure outside and inside diameters. This is the most reliable method for obtaining correct values.
4) When the main bearing metal is worn, replace it with a new one. When crank journal or crank pin is worn, replace with an undersized metal. (In this case, crankshaft must be ground accordingly.) Metals undersized by 0.5, 0.75, 1.0, 1.5, and 2.0 are available as standard service parts.
5) When replacing main bearing metal, replace upper and lower shells as a pair.
<Extraction and installation>
1. Remove main bearing cap tightening nut and cap.
2. Holding crank journal lubricating hole upward, insert main bearing extraction tool.
3. Turn the crankshaft in regular rotation direction until bearing appears completely, then stop turning and take out metal.
4. Remove debris from surface of metal ; of surface defects, remove only burrs.
5. Assembling in reverse of above process.
6. When metal is inserted, it can be pushed in about 1/3 way by hand; from that point, hold it with the tool by its butt end and turn the shaft slowly without forcing it.
7. If the metal fit is too tight, it is advisable to hold the crankshaft using an adjacent cylinder. A lower metal insertion tool is optionally available.
8. Ascertain that metal is position snugly inside the housing.
9. Make sure that main bearing metal with claw is set in the proper direction at cap side.
10. Refrain from applying too much torque to main bearing cap fixing bolt.

Thrust bearing metal

1) Thrust bearing metal, provided on both sides of rearmost cylinder journal, limit crankshaft movement in the axial direction.
2) Thrust bearing metal clearance is not adjustable, so worn bearings should always be replaced with new ones.
3) For extraction and installation of the thrust bearing metal, follow the procedure given for the main bearing.
4) The thrust bearing metal consists of upper and lower pieces. In assembly, take care not to create one-sided contact and check side clearance well.  Be careful not to install it upside down.
5) Before measuring side clearance, move crankshaft toward front or rear using a crowbar.


1) Although crankshaft is designed with ample strength and rigidity, care should be taken as to the following , which may result in crankshaft breakage:
1. When the engine is operated for a long period at critical speed, with torsional vibration
2. When operated with crankshaft deflection exceeding the allowable limit.
3. When there is excessive clearance between crankshaft and bearing, or uneven wear of crankshaft.
2) When there is burning of crankshaft or bearing due to depletion of oil, etc., carefully check for cranks using color penetrate check method or the like.
3) When crankshaft must be reground because of uneven wear or hair cracks consult manufacturer.
<Items to check and measure>
1. Scratches or dents on bearing surface, condition of fit-up, uneven or abnormal wear
2. Fillet portion and lubricating oil hole in bearing (color penetrate testing method)
3. Soiling or clogging of lubricating oil hole
4. Loose balance weight fixing bolt
5. Crankshaft deflection
6. Contours of pin and journal
7. Surface hardness: if hardness degrades below the specified value, consult with the manufacturer.
<Precautions for disassembly and re-assembly>
1. With sheeting, protect bearing pat from damage during oil hole carefully and air blow dry.
2. Wash lubricating oil hole carefully and air blow dry.
3. Clean bearing surface thoroughly to keep it free from dirt.
Measurement of crankshaft deflection

Timing Gear, Camshaft and Related Parts

Timing gear
1) Overhaul timing gear every two years; check gear tooth surfaces and perform color penetrant check.
2) Improper backlash not only increases noise and vibration but also creates pitting or burrs on tooth surfaces. Therefore, during overhaul if anything abnormal is observed with regard to the backlash, replace either the bearing or gear with a new one.
1. Disassembly connecting pipe.
2. Dismount auxiliary equipment (Lubricating oil pump, cooling water pump. etc.)
3. Remove idle gear shaft holder.
4. Remove gear case.
5. Remove auxiliary equipment drive gears.
6. Extract idle gear.
7. Crank gear is shrinkage-fit to crankshaft. Refrain from extracting it unless it is replaced with a new one.
1. Timing gear tally marks are provided on the side of each gear. Check marks carefully in assembling
2. When extracting idle gear, bring the cutout portion on auxiliary equipment drive gear mounting boss to the gear meshing position and then extract it.
3. When shrinkage-fitting, heat crank gear in oil bath to around 150180C and set it quickly at specified position.
Item to check and measure>
1. Fit-up, wear and pitting, if any, of tooth surface.
2. Contact and wear on bearing and shaft
3. Loose bearing mounting bolt
4. Gear backlash
5. Clearance between bearing and shaft


 The camshaft is provided with a thrust bearing which serves to prevent the shaft from moving in the axial direction. If the clearance between bearing and shaft increases, breakage of the governor driving bevel gear, or governor malfunction may occur. Therefore, the clearance should be checked from time to time.  If camlift decreases due to an abraded cam, the camshaft should be pulled to replace the cam with a new one.
1. Disassemble gear case front cover
2. Disassemble governor drive gear.
3. Remove cam bearing (thrust bearing) at the front end.
4. Extract cam bearing lubrication bolt (which is concurrently serving as cam bearing locator)
5. After removing each tappet, move camshaft toward governor side.
6. After cam bearing comes off the engine frame ,disassemble cam bearing bolt.
7. Remove cam bearing.
8. Extract camshaft toward governor side.

The intake and exhaust cams are shrinkage-fit to the camshaft directly; the fuel cams are tightened on the taper sleeve.
Extraction and installation>
1. With camshaft firmly second, knock cams out with a brass bar or similar soft metal piece, or draw them out with an oil jack using a suitable jig.
2. Detach fuel cam using fuel cam removing nut and take it out with taper sleeve.
3. To make extraction and installation easier, each cam, from shaft ends to center, has a diameter  0.1mm larger than one before. Diameter is marked on each cam.
4. Pay attention to the mark in reassembling and install each cam in the correct position.
. When installing the cams, heat them in an oil bath to approximately 150180C and install them in their prescribed positions. Take care not to heat over 180C ; otherwise, the cam may be changed in structure and lose strength.
6. Misalignment between cam and tappet roller should be kept to within 0.5mm. For this purpose, it is advisable to put the position mark on the camshaft before extracting the cam.
<Items to check and measure>
1. Pitting or wear on cam surface
2. Loosely fit cam
3. Clearance between camshaft and bearing
4. Clearance between thrust bearing

Adjustment of fuel cam

Fuel cam should be adjusted when Pmax is abnormal, and only after the operator has clearly determined the true cause of the disorder; it should never be handled without reason. The data shown on the factory data sheet are for operation on diesel fuel oil. When switching to heavy fuel oil, valve of Pmax and exhaust gas temperature vary, bur no adjustment is needed for Pmax unless it exceeds the prescribed limit.
<Adjustment procedure>
1. The fuel oil cam removing nut is located at the right side, and the fixing nut at the left in a standard engine. Align the marked line on the removing nut with the base line on the side of the cam and read the scale at the sleeve end. It is recommended that the tappet roller be placed on the base circle line of the cam.
In engines modified for reverse rotation , be careful the positions of removing nut and tightening nut are reverse of those in standard engines.
2. Loosen fixing nut (right- handed thread).
(Push wrench upward.)
3. Turn cam removing nut and detach taper sleeve of cam.
4. Return removing nut, align to read position referring to cam shifting hole and shift cam either to advance or delay position.
5. When cam is shifted in the rotation direction, the timing become earlier.  The maximum combustion pressure Pmax change by 35/cm2  per notch on the cam scale.
6. While holding cam, fix it in position by turning tightening nut.
7. Put removing nut to collar end of taper sleeve and clamp it. Never clamp it at the cam side.
1. Deviation between the Pmaxs in the cylinders should be kept within 3kg/cm2  while observing the requirement of the ceiling; the total pressure must not exceed design Pmax valve plus 3kg/cm2  in any case.
Pmax is increased by advancing injection timing and decreased by delaying it.
2. When tightening cam-fixing nut, spray anti-seizure agent
Do not spray anti-seizure agent on tapered portion.
As the taper sleeve breaks in quickly, check it periodically in accordance with Maintenance intervals in instruction for each engine, and tighten I further if necessary.
3. Misalignment between cam and tappet roller should be within 0.5mm.
Insufficient tightening of fuel cam tightening nut may cause fuel cam slippage, resulting in ill-timed fuel injection .  To avoid this, take special care to tighten nut securely to the specified torque.

Fuel injection Pump

When fuel injection pump is replaced, align marked line on plunger guide with basic line by means of push rod adjusting shim inside tappet.  However, fuel injection timing adjustment via this shim, should strictly be avoided since the delivery via may be pushed up with the plunger.

Fuel injection pump tappet
1) Since extreme pressure will imposed on the tappet roller at the initial pushing stage of the fuel cam, the utmost care should be taken that the cam is completely parallel with the roller.
2) If the spring inside the tappet is broken, the governor will malfunction or the maximum combustion pressure will change.
Check the spring on such occasions.
3) If a scratched roller is continuously used as it is, it may damage itself or the cam. Accordingly, repair the scratch with an oil stone , etc. before use.
4) Because the tappet roller bush is subject to great pressure, it is liable to wear quickly; therefore timely inspection and wear measurement are necessary.
5) The o-ring used for the fuel injection pump mount should be replaced with a new one at each overhaul.
1. Take out fuel injection pump.
2. Extract fuel injection pump mount.
3. Extract push rod
4. Extract tappet set screw on mount.
5. Extract tappet.
6. Extract roller pin and take out roller.

Intake and exhaust tappets
1) Intake and exhaust tappets should be handled in the same as fuel injection pump tappet.
2) If tappet roller outer diameter or roller shaft and bush are abraded, valve end clearance increase, changing opening/closing timing of intake and exhaust valves and adversely affecting combustion. For this reason, periodic inspection and wear measurement are essential.
3) If sticky exhaust or intake valves is found, inspect it; if left unattended, it may bend push rod or cause cracks in push rod seat.
4) When push rod and protective pipe have been extracted, cover hole so that no foreign matter can fall inside.  Foreign matter may damage push rod and seat.
1. Remove push rod and protective pipe.
2. Disassemble tappet tightening nut and extract tappet guide from engine frame.
3. Extract set screw from tappet guide.
4. Extract tappet.
5. Extract roller pin and take out roller.


1) Since the governor controls engine speed, it should be maintained in the best working condition at all times.
2) The governor should nor be overhauled on site. Although the overhauling procedures are described in the separate instruction, it is advisable to have it overhauled by the manufacturer.
3) For further details on handling, refer to separate manual for governor.

Governor driving gear
1) The governor driving bevel gear is fitted at the leading end of the camshaft, together with the pump driving gear, via a cushion spring which frees the governor from torsional vibration.
2) To check the condition of the cushion spring, turn gear in both directions while checking fitting of gear tooth surfaces. Overhaul and inspect once every two years.
1. Remove governor gear fixing nut.
2. Extract pump driving gear and governor driving gear assemblies as assembled.
3. Remove pump driving gear set bolt.
4. Remove washers for governor driving gear and pump driving gear
5. Remove cushion spring and cushion spring seat.
Do not over tighten governor driving gear tightening nut; otherwise, cushion becomes ineffective.

Fuel control device
1) Refrain from undue adjustment of fuel gear injection pump rack.
2) If link pin and other joint parts or level set screw come loose misposition during operation, governor control is lost, resulting in over-speed. To avoid this, check joint parts from time to time.
3) Governor link spring should not be disassembled.  If disassembly is absolutely necessary, measure and record spring fitting length (L) so that it can be reassembled to precisely the same fitting length. If the spring is fitted at a longer (weaker) length, the force from the governor will no longer be transmitted.
Conversely, if it is fitted at a shorter (strength) length, then the fuel cutoff device cannot function.
4) Check for deflection in the governor link system.
5) With control level set at stop position, check that graduation on rack register 0

Inter cooler

1) The inter cooler is likely to be soiled at the cooling water side and the air side. Inspect and clean it at appropriate intervals, determined with reference to the Maintenance intervals and according to the actual operating conditions of the engine and loss in performance, if any.
2) Wet inside of cooling pipe slightly with water and clean with a nylon brush.
3) Clean outside of cooling pipe with compressed air.  If soiled heavily with oil, etc., dip cooling pipe, with water chamber detached, in a neural detergent bath. After cleaning, rinse with clean water and let dry.
4) Check condition of protective zinc once every 6 months. Adjust inspection interval depending on degree of wear.
5) The drain separator installed at the inter cooler air outlet should also be cleaned at each overhaul.

Fuel Oil System

Fuel oil pump
1) Fuel oil pump specified for use with Diesel fuel oil.
Overhaul and inspection>
1. Since the fuel oil pump is small, there should never be any strain applied from external piping, which may result in breakage of pump mount.
2. A check valve is provided to allow fuel oil to flow down via the head when the engine is at rest, permitting priming. Be careful of damage to check valve or seat, which may result in depletion of fuel oil.
3. Average life of oil seal and ball bearing is two to three years.
1. Take special care not lose the check valve, a tiny steel ball.
2. Do not use packing on mating surface of pump body and cover. Apply proper sealant to mating surface.
3. Diesel fuel oil pump of the same type is used for special specification fitted with nozzle cooling system.

Lubricating Oil System

Lubricating oil pump
1) The lubricating oil pump is located under the crankshaft beside the auxiliary equipment driving gear. Its backlash is designed to be slightly larger than required so that it can drive the pump even after the main bearings are worn.  Backlash : 0.30.6mm
2) Since the lubricating oil pump is of the gear type , the clearance between casing and gears is very closely related to volume of discharge and lift. Check clearance at disassembly.
1. Packing should not be used on the matching face between section plate and pump cover, and between section plate and gear box and pump body.
2. When installing driving gear, tapered part should be tightened securely.
3. If suction pipe is not adequately connected, pump may suck in air and pressure may not rise. Therefore, see to it that pipe is connected positively.
4. Arrow mark indicating normal flow direction is provided on pump cover. Assemble in correct direction so that oil release hole comes to delivery side.
5. Be sure to overhaul safety valve provided on pump cover and check for sticking. If any trace is fond, repair place by lightly applying an oil stone.
6. Check bearing and oil seal at time of overhaul and replace them as necessary.

Lubricating oil cooler
1) Accumulated sludge on surface of cooling tube reduces cooling effect significantly. Wash periodically according to the Maintenance intervals.
2) It is recommended that steam and neutral detergent be used as Neos, etc., for effective cleaning. Carry out post-washing treatment correctly.
3) Oil may leak at packing due to expansion or shrinkage of internal cooling tube. Tighten packing additionally from time to time to time or replace it with new as required.
1. The cooling tube should be handled with great care. Be sure not to apply heat over 150C to joint between holder plate and cooling tube.
2. A hydrostatic test should be conducted after the oil cooler is assembled.

Lubricating oil pressure regulating valve.
1) If oil pressure fails to rise even after the adjusting screw is driven in, the valve may be struck.  Check valve after checking for other possible causes for low oil pressure; oil shortage, air entry, defective lubricating system , etc.
2) If valve is struck, pressure change significantly, depending on oil viscosity and engine speed. If the pressure change exceeds 1.5kg/cm2, check the valve.
It should be remembered, however, that oil pressure may increase over the specified valve when the engine speed is increase rapidly during cold weather, but as the oil temperature raises, oil pressure will drop to normal.
1. When overhauling, carefully inspect for sludge accumulation in oil passage and regulating valve. If necessary, remove and clean.
2. If any scratches are noted on pressure regulating valve, dress with oil stone, and check that valve moves lightly.

Rocker Arm Lubricating System Related Parts
1. Pump rotor and drive shaft are tiny parts. Handle them with beat care and do not remove out forcibly.
2. Oil seal, o-ring and packing should be replaces with new ones.
3. Check and clean safety valve incorporated in pump cover when overhauling.
4. Overhaul and check pump once every two years.
5. Drive shaft and rotor (both inner and outer parts) should me replaces as a set.

Rocker arm lubricating oil filter
1. Since rocker arm lubricating system lubricates sections subject to heavy contamination, drainage at least once a week and overhaul and cleaning once a month are necessary.
2. Pressure regulating valves and oil tank used in the system should also be overhauled and cleaned from time to time.
 Rocker arm lubricating oil pressure   regulating valve.
1. When disassembling, thoroughly remove sludge accumulated in oil passage and pressure regulating valve.
2. When reassembling, check for deformed packings and replace with new if worm heavily.

Cooling Water System

Cooling water pump
1. Check thoroughly for wear of impeller and mouth ring as wear in these parts tends to lower pump head.  (Allowable wear limit)
 Clearance between mouth ring and impeller; 0.75mm
2. Mechanical seal is an important part that seals pump chamber from atmosphere. If it is fit inadequately, water leakage may result from air chamber at back of section wall via drain pipe. Average life of mechanical seal: 4,0006,000hrs.
3. Cooling water pump run at 2,000 rpm on average is directly coupled with engine and subject to engine vibration. Therefore, ball bearing used therein is most likely to wear. Overhaul the pump and replace ball bearing with new one at regular intervals. Average life of ball bearings 7,000 to 10,000hrs. It is desirable to replace the ball bearing earlier, since continued use of a worn bearing may result in driving gear damage at crankshaft side, involving unnecessarily higher repair cost.
4. Since the pump section is subject to servere vibration, check carefully for pitting or scratching on gear face when overhauling. Such surface, if any, should be dressed with a set of files or the gear as a whole with a new one if it has worn beyond the allowable limit.
5. As allowance for ambient temperature fluctuation or strain causes by faulty piping, driving gear is made to tolerate a backlash of 0.3 to 0.6 mm
6. Other items to check
.Traces of cavitation or corrosion on impeller
.Drive shaft wear at oil seal sliding portion
.Deterioration or cracks on oil seal rubber
1. Remove connecting pipe.
2. Remove pump cover.
3. Loosen impeller tightening nut.
In standard engine specification, the nut is left-hand threaded (turned clockwise to loosen when viewed from flywheel.)
4. Remove impeller.
Impeller is fixed on taper-fit method. To loosen it, strike the vane end two to three times with a wooden hammer. The use of a jig is also recommended for extracting impeller.
5. Remove mechanical seal .
6. Dismount pump body.
7. Remove seal holder.
8. Remove driving gear fixing nut.
9. Extract driving gear.
10. Remove bearing holders.
11.Extract shaft along with ball bearing
12. Extract bearing from shaft. (Shape of bearing differs slightly, according to the type of engine.)
Do not get oil on carbon part of mechanical seal.
Incorporate oil seal in the right direction as shown in the exploded view below.