Diagnostic Analysis

DIAGNOSTIC ANALYSIS

Within the broad scope of Diesel engine technology, learning why engines fail to operate as they should is just as important as knowing how and why engines do operate properly. The practical application of such knowledge is commonly referred to as "Diagnostic Analysis". This investigative ability is not limited to trouble-shooting, such as finding the probable cause of a problem. When properly exercised, it goes even further, in determining how to correct the problem once its cause has been identified and in some cases it may indicate how to avoid a recurrence of the problem. It is applicable to pre-operational problems such as finding out why an engine fails to start, and to operational irregularities such as identifying the cause of unusual noise or vibration. It may also be used in post-operative investigation of mechanical failure and during an over¬haul, in determining the cause of abnormal wear.

Diagnostic analysis however, is not simply acquired from any textbook or technical school. Expertise of this nature is the product of an in-depth knowledge of engine design, extensive operating and repair experience with various types of engines and the ability to accurately interpret engine test data. Proper analysis of external symptoms and systematic diagnosis of their probable causes are the most practical means of isolating the nature of problems and of judging the potential seriousness of same. The effectiveness of this approach lies not in waiting for a breakdown to occur, but in adopting a pro-active stance of alertness to any deviations from normal operating conditions and by closely monitoring operational parameters so as to detect apparently abnormal trends before they do become problematic. In addition to monitoring engine operation, evaluating log sheets and periodically reviewing the manufacturer's technical manuals and service bulletins, all engine-related gauges and instruments should be maintained within calibration, including torque wrenches, compression test indicators, injector calibration pumps, etc., and reliable test equipment kept readily available. Should problems occur, their resolution may be typical of the examples shown in the following Diagnostic Analysis Charts.

1. SYMPTON: ENGINE FAILS TO START OR IS DIFFICULT TO START.

1.a PROBABLE CAUSE: LOW AIR PRESSURE. 1.a CORRECTION: Check air pressure in receiver and verify compressor operation. Ensure pressure is adequate and that all starting air system valves are properly positioned.

1.b PROBABLE CAUSE: LOW BATTERY OUTPUT. 1.b CORRECTION: Enture battery is fully charged and check battery cable connections and ground strap for tightness. Check for faulty solenoid switch.

1.c PROBABLE CAUSE: LOW OIL PRESSURE. 1.c CORRECTION: Ensure hydraulic starting accumulator is fully charged. Check oil level in hydraulic reservoir and fill as necessary. Check all hose and pipe connections in hydraulic starting system for tightness.

1.d PROBABLE CAUSE: INSUFFICIENT FUEL. 1.d CORRECTION: Check fuel level in day tank or supply tank and re-fill as necessary. Ensure all fuel system valves are properly positioned. Inspect fuel filters for clogging and change ads needed. Make sure fuel system is properly primed and free of air.

1.e PROBABLE CAUSE: ENGINE IS TOO COLD. 1.e CORRECTION: For small engines, energize glow plugs, if installed, or apply starting fluid to air intake or pre-heat cooling system is possible. For large engines, circulate pre-heated water through the cooling system.

1.f PROBABLE CAUSE: OVERSPEED STOP IS TRIPPED. 1.f CORRECTION: Re-set overspeed stop. Ensure governor linkage has freedom of movement.

1.g PROBABLE CAUSE: WATER IN FUEL 1.g CORRECTION: Open condensate drain cock under fuel day tank and drain off all water and sediment until only clear fuel flows, than close drain cock. Open bottom drain cock and loosen top vent plug of fuel strainer, primary fuel fitter and secondary fuel filter (if applicable), until only clear fuel flows, then close cocks and tighten vent plugs. Try to start engine. If unsuccessful, loosen fuel Injector lines to all injectors. Roil engine over on starter while observing leakage at loosened fuel injection line connections. Purge Injection lines until only clear fuel is evident then tighten all loosened connections and re-start engine.

1.h PROBABLE CAUSE: JACKING GEAR INTERLOCK IS ENGAGED. 1.h CORRECTION: Check jacking gear position'and disengage if necessary. If jacking gear is already disengaged, check for jammed interlock, defective or disconnected interlock linkage and repair as warranted.

1.i PROBABLE CAUSE: WATER IN CYLINDER. 1.i CORRECTION: If water is suspected, open all cylinder test cocks and roll engine over on starter while observing tes•cocks for signs of water discharge. If engine is not equipped with cylinder test cocks, loosen all fuel injector hold-down nuts but do not remove nuts completely, and do not loosen any fuel injection lines. Crank engine with starter with throttle in closed position, while observing injectors for signs of water discharge. If water is evident during first test roll, allow,engine to.come to a complete stop and after about five mihutes, repeat test roll with either cylinder test cocks open or with fuel injector hold-down nuts loosened. If water is still evident during second test roll, check for possible defective cylinder head gasket; loose cylinder head hold-down nuts; cracked head or cracked liner, and repair as warranted. Also check the cooling water expansion tank for evidence of cloudy sight glass; or an oil film floating on the top of the water in the sight glass, both conditions are indicative of a possible crack in a cylinder head or liner.

2. SYMPTON: ENGINE STOPS SUDDENLY.

2.a PROBABLE CAUSE: EMPTY FUEL TANK. 2.a CORRECTION: Replenish fuel tank as necessary and prime entire system from tank to injectors to ensure system is thoroughly purged of air.

2.b PROBABLE CAUSE: FUEL TRANSFER PUMP IS INOPERATIVE. 2.b CORRECTION: Repair or replace transfer pump as necessary and repeat fuel system priming as above.

2.c PROBABLE CAUSE: EXCESSIVE OVERLOAD. 2.c CORRECTION: Determine cause of overload, such as stalling due to operating in high gear, in the case of an automotive engine; excessive electrical, load, in the case of a Diesel-generator, fouled propeller, in the case of a marine engine; broken transmission gear tooth or seized bearing, in the case of a geared-drive system. Correct stalling problem, if feasible, and re-start engine and gradually increase speed to normal prior to re-applying the load.

2.d PROBABLE CAUSE: OVERSPEED STOP TRIPPED. 2.d CORRECTION: Determine the cause of tripping and correct same. Re-set overpeed stop and re-start engine.

2.e PROBABLE CAUSE: LOW LUBE OIL PRESSURE. 2.e CORRECTION: Determine lause of low oil pressure. Check crankcase oil level, condition of oil filters and accuracy of oil pressure gauge. Refer to SYMPTON No. 9, LOW ENGINE OIL PRESSURE. Read PROBABLE CAUSES listed "a" through "j" and applicable CORRECTIONS.

2.f PROBABLE CAUSE: HIGH COOLING WATER TEMPERATURE. 2.f CORRECTION: Refer to SYMPTON No. 11, ENGINE OVERHEATS. Read PROBABLE CAUSES listed "a" through "g" and applicable CORRECTIONS.

2.g PROBABLE CAUSE: FUEL FILTERS CLOGGED. 2.g CORRECTION: Change filters and prime fuel system thoroughly.

2.h PROBABLE CAUSE: AIR IN FUEL SYSTEM. 2.h CORRECTION: Check fuel system, between fuel tank outlet and fuel transfer pump inlet for possible source of air, such as loose or cracked connections, split hoses, etc. Tighten or replce connections and/or hoses as applicable. Prime entire system from tank to injectors to ensure system is thoroughly purged of air.

2.i PROBABLE CAUSE: WATER IN FUEL. 2.i CORRECTION: Refer to SYMPTON No. 1, ENGINE FAILS TO START OR IS DIFFICULT TO START. Read PROBABLE CAUSE "g" and applicable CORRECTIONS.

2.j PROBABLE CAUSE: GOVERNOR FAILURE. 2.j CORRECTION: Check governor oil level if applicable. Check governor mounting bolts for tightness. Check linkage between governor and fuel injection pumps for possible binding or exc6ssive play, and repair as necessary. Adjust, repair or replace governor as necessary. If governor is replaced, verify that the replacement unit is calibrated to suit specific engine operating requirements.

3. SYMPTON: ENGINE LACKS DOWER, SPEED IS UNSTABLE.

3.a PROBABLE CAUSE: ERRATIC GOVERNOR OPERATION. 3.8 CORRECTION: Refer to SYMPTON No. 2, ENGINE STOPS SUDDENLY. Read PROBABLE CAUSE "j" and applicable CORRECTIONS.

3.b PROBABLE CAUSE: IMPROPER FUEL 3.b CORRECTION: Test run engine for one hour and record operational parameters. Draw samples of suspect fuel and send to laboratory for analysis, discard remaining suspect fuel in accordance with applicable EPA regulations and replace with fresh fuel of known, acceptable analysis. Replace all fuel filters and strainers and prime fuel system thoroughly. Compare engine operational parameters between both fuels under identical load conditions.

3.c PROBABLE CAUSE: IMPROPER TIMING. 3.c CORRECTION: Check timing of fuel injection pumps and correct as necessary. For unit injector systems, check timing of each unit injector individually, including height of tappet and setting of control rack. In calibrating tappet height ensure tappet height gauge tool fits into the appropriate orifice in injector body at the correct depth of penetration. NOTE: If there are impurities within the orifice, preventing penetration of the height gauge to the proper depth, the height of the unit injector tappet may exceed applicable specifications, resulting in premature injection and insufficient volume. Review engine operating log for abnormal exhaust temperature readings and remove any suspect fuel injectors for test and calibration. Check timing of intake and exhaust valves as applicable, adjust as warranted. Check gear train for accuracy of timing, excessive backlash, broken gear teeth, slack timing chain or badly worn timing chain rollers and sprockets. Repair or replace as required. Inspect camshaft for chipped or badly worn cam lobes, excessively worn bearings and journals. Repair or replace as necessary.

3.d PROBABLE CAUSE: VALVS STICKING, LEAKING OR VALVE SPRINGS BROKEN. 3.d CORRECTION: Take and record all valve tappet clearance readings. Ensure all valves have been receiving adequate lubrication. Remove cylinder head (s) as applicable. Check valves for indications of leakage, binding or excessively worn valve stem guides and valve springs for proper tension. Repair or replace parts as warranted. Re-assemble cylinder head (s) and re-install, using correct torque wrench. Check and record timing and tappet clearances.

3.b PROBABLE CAUSE: IMPROPER FUEL

3.b CORRECTION: Test run engine for one hour and record operational parameters. Draw samples of suspect fuel and send to laboratory for analysis, discard remaining suspect fuel in accordance with applicable EPA regulations and replace with fresh fuel of known, acceptable analysis. Replace all fuel filters and strainers and prime fuel system thoroughly. Compare engine operational parameters between both fuels under identical load conditions.

3.c PROBABLE CAUSE: IMPROPER TIMING.

3.c CORRECTION: Check timing of fuel injection pumps and correct as necessary. For unit injector systems, check timing of each unit injector individually, including height of tappet and setting of control rack. In calibrating tappet height ensure tappet height gauge tool fits into the appropriate orifice in injector body at the correct depth of penetration. NOTE: If there are impurities within the orifice, preventing penetration of the height gauge to the proper depth, the height of the unit injector tappet may exceed applicable specifications, resulting in premature injection and insufficient volume.

Review engine operating log for abnormal exhaust temperature readings and remove any suspect fuel injectors for test and calibration. Check timing of intake and exhaust valves as applicable, adjust as warranted. Check gear train for accuracy of timing, excessive backlash, broken gear teeth, slack timing chain or badly worn timing chain rollers and sprockets. Repair or replace as required. Inspect camshaft for chipped or badly worn cam lobes, excessively worn bearings and journals. Repair or replace as necessary.

3.d PROBABLE CAUSE: VALVES STICKING, LEAKING OR VALVE SPRINGS BROKEN.

3.d CORRECTION: Take and record all valve tappet clearance readings. Ensure all valves have been receiving adequate lubrication. Remove cylinder head(s) as applicable. Check valves for indications of leakage, binding or excessively worn valve stem guides and valve springs for proper tension. Repair or replace parts as warranted. Re-assemble cylinder head(s) and re-install, using correct torque wrench. Check and record timing and tappet clearances.

3.e PROBABLE CAUSE: PARTIALLY CLOGGED FUEL FILTERS.

3.e CORRECTION: Change filters and prime system thoroughly. Re-check fuel transfer pump pressure.

3.f PROBABLE CAUSE: IMPROPERLY OPERATING FUEL INJECTORS.

3.f CORRECTION: Check exhaust temperatures for uniformity. Remove, repair or re-calibrate fuel injectors as necessary and re-check exhaust temperatures. If after correcting apparent injector problems, exhaust temperatures are still erratic or abnormal, check each individual fuel injection pump for proper operation. Suspect or defective fuel injectors should be checked for 1) proper calibration of injection pressure; 2) carbonized or clogged atomizer orifices; 3) leaking or sticking needle valve; 4) weak or broken spring. If it becomes necessary to replace a fuel injector of the jerk type system, it is preferable to replace a defective unit with one that has been factory-refurbished and calibrated. Upon completion of repairs take and record exhaust temperatures of all cylinders under normal load.

3.g PROBABLE CAUSE: DEFECTIVE FUEL INJECTION PUMP

3.g CORRECTION: Prior to disturbing fuel injection pumps, verify that the fuel transfer pump and the fuel pressure gauge are both in proper working order. Repair or replace fuel injection pump as required. Suspect or defective fuel injector pumps should be checked for 1) weak or broken discharge valve spring; 2) leaking discharge check valve; 3) worn or binding plunger and barrel assembly; 4) weak or broken plunger tappet spring; 5) worn, or damaged control rack and pinion assembly. If it becomes necessary, to replace a defective fuel injection pump of the jerk type system, it is preferable to replace a defective unit with one that has been factory-refurbished and calibrated Upon completion of repairs take and record exhaust temperatures of all cylinders under normal load.

3.h PROBABLE CAUSE: LOW CYLINDER COMPRESSION.

3.h CORRECTION: Take compression readings while engine is hot, repeat test on the cylinder with the lowest reading. Check for broken or worn piston rings; bad head gasket; leaking valves; cracked liner or cylinder head. Repair or replace as warranted and re-take compression readings on all cylinders.

3.e PROBABLE CAUSE: PARTIALLY CLOGGED FUEL FILTERS. 3.e CORRECTION: Change filters and prime system thoroughly. Re-check fuel transfer pump pressure.

3.f PROBABLE CAUSE: IMPROPERLY OPERATING FUEL INJECTORS. 3.f CORRECTION: Check exhaust temperatures for uniformity. Remove, repair or re-calibrate fuel injectori as necessary and re-check exhaust temperatures. If after correcting apparent injector problems, exhaust temperatures are still erratic or abnormal, check each individual fuel injection pump for proper operation. Suspect or defective fuel injectors should be checked for 1) proper calibration of injection pressure; 2) carbonized or clogged atomizer orifices; 3) leaking or sticking needle valve; 4) weak or broken spring. If it becomes necessary to replace a fuel injector of the jerk type system, it is preferable to replace a defective unit with one that has been factory-refurbished and calibrated. Upon completion of repairs take and record exhaust temperatures of all cylinders under normal load.

3.g PROBABLE CAUSE: DEFECTIVE FUEL INJECTION PUMP 3.g CORRECTION: Prior to disturbing fuel injection pumps, verify that the fuel transfer pump and the fuel pressure gauge are both in proper working order. Repair or replace fuel injection pump as required. Suspect or defective fuel injector pumps should be checked for 1) weak or broken discharge valve spring; 2) leaking discharge check valve; 3) worn or binding plunger and barrel assembly; 4) weak or broken plunger tappet spring; 5) worn, or damaged control rack and pinion assembly. If it becomes necessary, to replace a defective fuel injection pump of the jerk type system, it is preferable to replace a defective unit with one that has been factory-refurbished and calibrated. Upon completion of repairs take and record exhaust temperatures of all cylinders under normal load.

3.h PROBABLE CAUSE: LOW CYLINDER COMPRESSION. 3.h CORRECTION: Take compression readings while engine is hot, repeat test on the cylinder with the lowest reading. Check for broken or worn piston rings; bad head gasket; leaking valves; cracked liner or cylinder head. Repair or replace as warranted and re-take compression readings on all cylinders.

3.e PROBABLE CAUSE: PARTIALLY CLOGGED FUEL FILTERS. 3.e CORRECTION: Change filters and prime system thoroughly. Re-check fuel transfer pump pressure. 3.f PROBABLE CAUSE: IMPROPERLY OPERATING FUEL INJECTORS. 3.f CORRECTION: Check exhaust temperatures for uniformity. Remove, repair or re-calibrate fuel injectori as necessary and re-check exhaust temperatures. If after correcting apparent injector problems, exhaust temperatures are still erratic or abnormal, check each individual fuel injection pump for proper operation. Suspect or defective fuel injectors should be checked for 1) proper calibration of injection pressure; 2) carbonized or clogged atomizer orifices; 3) leaking or sticking needle valve; 4) weak or broken spring. If it becomes necessary to replace a fuel injector of the jerk type system, it is preferable to replace a defective unit / with one that has been factory-refurbished and calibrated. Upon completion of repairs take and record exhaust temperatures of all cylinders under normal load. 3.g PROBABLE CAUSE: DEFECTIVE FUEL INJECTION PUMP 3.g CORRECTION: Prior to disturbing fuel injection pumps, verify that the fuel transfer pump and the fuel pressure gauge are both in proper working order. Repair or replace fuel injection putt') as required. Suspect or defective fuel injector pumps should be checked for 1) weak or broken discharge valve spring; 2) leaking discharge check valve; 3) worn or binding plunger and barrel assembly; 4) weak or broken plunger tappet spring; 5) worn, or damaged control rack and pinion assembly. If it becomes necessary, to replace a defective fuel injection pump of the jerk type system, it is preferable to replace a defective unit with one that has been factory-refurbished and calibrated Upon completion of repairs take and record exhaust temperatures of all cylinders under normal load.

3.h PROBABLE CAUSE: LOW CYLINDER COMPRESSION.

3.h CORRECTION: Take compression readings while engine is hot, repeat test on the cylinder with the lowest reading. Check for broken or worn piston rings; bad head gasket; leaking valves; cracked liner or cylinder head. Repair or replace as warranted and re-take compression readings on all cylinders

3.i PROBABLE CAUSE: INSUFFICIENT AIR.

3.i CORRECTION: Check air intake screens, filter, silencer, piping and intake manifold for restriction to air flow, and clean as needed. Check scavenge air ports, and scavenge air manifold, exhaust ports and exhaust manifold and trunk for carbon build-up, and clean as needed. Check operation of scavenge air pump or blower, including gear or belt drive; check exhaust turbo-charger or super-charger as applicable. Ensure that air flow to and from pump, blower or charger is unobstructed and that gas flow into and out of turbine is normal. Check exhaust system for possible back pressure. NOTE: Some high speed two stroke cycle engines are fitted with emergency stop flappers at the scavenge blower intake, ensure that flapper is in the open position.

3.j PROBABLE CAUSE: COOLING WATER TEMPERATURE TOO LOW.

3.j CORRECTION: Refer to SYMPTON No. 1, ENGINE FAILS TO START OR IS DIFFICULT TO START. Read PROBABLE CAUSE "e" and applicable corrections.

3.k PROBABLE CAUSE: LOAD APPLIED TOO SUDDENLY AT LOW SPEED.

3.k CORRECTION: Increase engine speed and apply load gradually. If load can not be applied gradually, allow engine to attain normal operating speed and temperature before applying load.

3.l PROBABLE CAUSE: MISALIGNMENT BETWEEN ENGINE AND DRIVEN EQUIPMENT.

3.1 CORRECTION: Inspect engine alignment with that of its driven equipment and re-align as needed. Refer to SYMPTON No. 5, ENGINE VIBRATES. Read PROBABLE CAUSE "a" and applicable CORRECTIONS as warranted.

3.m PROBABLE CAUSE: MISFIRING CYLINDERS.

3.m CORRECTION: Refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSE "f' and applicable CORRECTIONS.

4. SYMPTON: ENGINE OVERSPEEDS

4.a PROBABLE CAUSE: TOO MUCH FUEL.

4.a CORRECTION: Inspect fuel injection pump control racks for proper setting, uniformity and freedom of movement, from no fuel to full fuel position. If the engine is equipped for a Pressure-Volume indicator, take a set of P-V cards, 3 cards on each cylinder and record corresponding exhaust temperatures simultaneously. Examine all P-V diagrams for combustion peak characteristics indicative of leaking atomizer nozzles before disturbing any injectors. If engine is equipped for a Firing Pressure Indicator, take a set of readings on all cylinders and record corresponding exhaust temperatures. Otherwise, remove all fuel injectors and use an injector test pump to check atomization, seating of needle valve or leakage past same; condition of each atomizer nozzle, and correct injection pressure setting. If leakage is evident replace atomizer nozzle assembly. If necessary, disassemble injector, replace spring and calibrate for proper injection pressure.

4.b PROBABLE CAUSE: IMPROPERLY OPERATING GOVERNOR.

4.b CORRECTION: Refer to SYMPTON No. 2, ENGINE STOPS SUDDENLY. Read PROBABLE CAUSE "j" and applicable CORRECTIONS.

4.c PROBABLE CAUSE: LUBE OIL REACHING COMBUSTION CHAMBER.

4.c CORRECTION: Take and record firing pressures and corresponding exhaust temperatures. Before stopping engine, observe exhaust effluent for indications of burning lube oil. Stop engine and take compression readings on all cylinders while engine is hot. If compression readings are normal check for possible source of oil entering the cylinders, such as leaking scavenge blower oil seals, in the case of two-stroke cycle engines. In the case of four stroke cycle engines, check for worn valve guides whereby valve lubrication may migrate down the intake valve guide and into the cylinder. Check oil temperaturre. If oil is not properly cooled, crankcase oil may vaporize and be drawn into the cylinder. If compression readings are very low and corresponding exhaust temperatures higher than usual, the engine should be inspected for broken, stuck or worn piston rings, badly worn cylinder liner or cracked piston. NOTE: In the case of worn exhaust valve guides, lube oil may migrate into the exhaust valve compartment but not enter the cylinder. When the exhaust valve opens, the accumulated oil is blown out with the exhaust.

5 SYMPTOM- ENGINE VIBRATES.

5.a PROBABLE CAUSE: MISFIRING CYLINDERS.

5.a CORRECTION: Check for faulty fuel injectors. Refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSE 'r and applicable CORRECTIONS. Also take compression readings while engine is hot and repeat test on the cylinder with the lowest reading. If warranted, refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSE "h"and applicable CORRECTIONS.

5.b PROBABLE CAUSE: LOOSE HOLD-DOWN BOLTS.

5. b CORRECTION: Inspect all hold-down bolts or mounting bolts for slack nuts and signs of shear stress or fretting and worn or stretched threads. Also check bolt holes in engine baseplate and foundation for signs of elongation and repair as warranted. Replace all defective bolts and tighten to specified torque. Inspect engine alignment with that of the driven unit, such as generator, gear case, drive shaft, etc., and re-align as necessary.

5.c PROBABLE CAUSE: UNBALANCED DRIVEN UNIT.

5.c CORRECTION: Inspect driven unit for loose hold-down bolts, loose or broken coupling bolts; misalignment; loose components; worn bearings; bent drive shaft or defective clutch. Repairor replace as needed and re-store balance to unit.

5.d PROBABLE CAUSE: LOOSE ENGINE COMPONENTS.

5.d CORRECTION: Inspect engihe for loose components including exhaust turbo¬charger or scavenge air blower; exhaust manifold; and vibration damper. Check all belt-driven accessories such as cooling fan, generator, power-take-off, and air compressor, etc., and adjust as necessary. Check gear train for misalignment, excessive backlash or broken teeth, worn bearings, etc. also check timing chain for lack of tension, worn rollers, worn or broken sprockets and bad bearings. Repair or replace as necessary. Check bolt torque on crankshaft counterweights and flywheel; re-tighten to specified torque as warranted, then take and record crankshaft deflection readings.

6. SYMPTOM: ENGINE KNOCKING NOISE

6.a PROBABLE CAUSE: IMPROPER FUEL.

6.a CORRECTION: Refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSE "b" and applicable CORRECTIONS.

6.b PROBABLE CAUSE; IMPROPER INJECTOR TIMING.

6.b CORRECTION: Refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSE "c" and applicable CORRECTIONS.

6.c PROBABLE CAUSE: LOOSE CONNECTING ROD.

6.c CORRECTION: Check connecting rod bottom end bolts for loose nuts, elongation or fretting and replace as needed. Examine bottom end bearing shells for excessive wear or damage and replace as necessary.

6.d PROBABLE CAUSE: LOOSE MAIN BEARING.

6.d CORRECTION: Inspect main bearings for loose nuts, check top and bottom halves of bearing shell for damage and replace as needed. Re-torque main bearing cap nuts and check cranshaft webs for possible deflection, if excessive, remove crankshaft and have it straightened or replaced. Ensure lubrication to main bearings is adequate.

6.e PROBABLE CAUSE: LOOSE PISTON PIN.

6.e CORRECTION: Inspect piston pin and all bushings for wear or damage and replace as necessary. Ensure oil passage through connecting rod is clear and that lubrication to piston pin is adequate. If either piston pin or piston pin bushings are found to be badly worn, closely inspect bottom end bearing shells also for possible wear or damage and replace as necessary.

6.f PROBABLE CAUSE: DAMAGED PISTON.

6.f CORRECTION: Stop engine, take and record comparative compression readings, to determine source of noise. Remove cylinder head and check suspect piston crown. Remove piston assembly and inspect cylinder liner for evidence of scuffing by broken piston rings. If damage is light, hone liner to remove scuffing marks and take micrometer readings of cylinder bore to determine if wear is excessive or can be compensated by use of over-size piston rings. If wear is excessive install new liner, and piston assembly. Examine lube oil and filter for presence of metallic perfidies; flush engine tube oil system and ensure crankcase is wiped dry and free of any foreign matter. After flushing, drain tube oil system completely, replace oil and install new filter elements.

6.g PROBABLE CAUSE: LOOSE VALVE TAPPETS.

6.g CORRECTION: Check tappet clearance of all valves and re-set as needed. Inspect valve mechanism for worn rocker arm bushings, broken or weakened valve springs, bent valve stems or push rods and worn tappet rollers. Replace as needed and re-check tappet clearances as warranted. Check tappet adjustment stud for surface wear or damaged thread and replace as necessary. If tappets are of the hydraulic lash adjuster type, inspect all parts for excessive wear and ensure oil passages are clear; replace with new as warranted. Also inspect camshaft for possible damage or excessive wear of cam lobes and repair or replace as warranted.

6.h PROBABLE CAUSE: INSUFFICIENT LUBE OIL CIRCULATION.

6.h CORRECTION: Check oil level in crankcase sump or external tank and replenish as necessary. Check pressure differential across tube oil filters and replace filter elements as required. Inspect oil pump suction screen or strainer for clogging or obstruction and clean as needed. Check tube oil pump pressure regulating valve spring for weakness and valve seat for presence of particulate matter. Clean, repair or replace as warranted. Check condition of lube oil pump shaft, drive chain or drive gears, repair or replace as necessary. Test oil pump for proper operation and normal delivery volume, and repair or replace pump as warranted. Flush lubrication system thoroughly, replace oil and install new filter elements. Remove tube oil pressure gauge for calibration and reinstall.

7. SYMPTON: ENGINE HISSING NOISE.

7.a PROBABLE CAUSE: AIR INTAKE LEAKAGE.

7.a CORRECTION: Inspect air intake piping and manifold for defective gaskets, leaking flanges, etc., and tighten or replace as needed.

7.b PROBABLE CAUSE: LEAKAGE OF PRESSURIZED AIR INTAKE.

7.b CORRECTION: Inspect air intake silencer, scavenge air blower or exhaust turbo-charger outlet, and after-cooler, if applicable. Check for defective gaskets, leaking flanges or open drains. Tighten or replace as required.

7.c PROBABLE CAUSE: EXHAUST DUCT LEAKAGE.

7.c CORRECTION: Inspect exhaust manifold and ducting to turbo-charger and muffler. Check for defective gaskets, leaking flanges or open drains. Tighten or` replace as necessary.

8. SYMPTON: ENGINE EXHAUST TEMPERATURE TOO HIGH.

8.a PROBABLE CAUSE: ENGINE OVERLOADED.

8.a CORRECTION: Refer to SYMPTON No. 2, ENGINE STOPS SUDDENLY. Read PROBABLE CAUSE "c" and applicable CORRECTIONS. Also re-check exhaust temperatures at each cylinder after correction of overload and re-check cooling water discharge from each cylinder and lube oil cooler outlet temperature.

8.b PROBABLE CAUSE: POOR GRADE OF FUEL.

8.b CORRECTION: Refer to $YMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSE "b" and applicable CORRECTIONS.

8.c8.c PROBABLE CAUSE: THERMOCOUPLES CARBONED. 8.c CORRECTION: Remove thermocouple unit from each cylinder. Clean off bi-metal probes of all carbon and inspect leads for damage, replace as warranted, re-install and test. NOTE: When replacing thermocouple leads be sure to use wire of the same gauge and length as the original wire. Otherwise, resistance may vary, resulting in an incorrect read-out on the pyrometer dial. 8.d PROBABLE CAUSE:` IMPROPER VALVE TIMING. 8.d CORRECTION: Check timing of intake and exhaust valves, adjust or correct as required. Check for proper tappet clearances and correct as warranted. Check gear train for proper timing, backlash, worn bearings or damage, and check timing chain (as applicable) for proper tension, worn rollers, worn bearings or damaged sprockets. Repair or replace as required. 8.e PROBABLE CAUSE: FUEL INJECTION TOO LATE. 8.e CORRECTION: Refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSES "c"; 1" and "g", and applicable CORRECTIONS. Also, refer to SYMPTON No. 2, ENGINE STOPS SUDDENLY. Read PROBABLE CAUSE ec" and applicable CORRECTIONS. Re-check exhaust temperatures At each cylinder after correction of problems. 9. SYMPTON: LOW ENGINE OIL PRESSURE. 9.a PROBABLE CAUSE: CLOG3ED FILTER OR STRAINER. 9.a CORRECTION: Check oil level in crankcase sump or external tank and replenish as necessary. Check pressure differential across tube oil filter and renew filter element as required. Remove strainer and clean or replace as warranted to ensure normal oil flow. If oil pressure remains low after replacement of filter elements, remove all lube oil pressure gauges for calibration and re-install. Start engine and re-check oil pressure, if still abnormal continue investigation.

8.c PROBABLE CAUSE: THERMOCOUPLES CARBONED.

8.c CORRECTION: Remove thermocouple unit from each cylinder. Clean off bi-metal probes of all carbon and inspect leads for damage, replace as warranted, re-install and test. NOTE: When replacing thermocouple leads be sure to use wire of the same gauge and length as the original wire. Otherwise, resistance may vary, resulting in an incorrect read-out on the pyrometer dial.

8.d PROBABLE CAUSE:` IMPROPER VALVE TIMING.

8.d CORRECTION: Check timing of intake and exhaust valves, adjust or correct as required. Check for proper tappet clearances and correct as warranted. Check gear train for proper timing, backlash, worn bearings or damage, and check timing chain (as applicable) for proper tension, worn rollers, worn bearings or damaged sprockets. Repair or replace as required.

8.e PROBABLE CAUSE: FUEL INJECTION TOO LATE.

8.e CORRECTION: Refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSES "c"; 1" and "g", and applicable CORRECTIONS. Also, refer to SYMPTON No. 2, ENGINE STOPS SUDDENLY. Read PROBABLE CAUSE ec" and applicable CORRECTIONS. Re-check exhaust temperatures it each cylinder after correction of problems.

9. SYMPTON: LOW ENGINE OIL PRESSURE.

9.a PROBABLE CAUSE: CLOGffD FILTER OR STRAINER.

9.a CORRECTION: Check oil level in crankcase sump or external tank and replenish as necessary. Check pressure differential across tube oil filter and renew filter element as required. Remove strainer and clean or replace as warranted to ensure normal oil flow. If oil pressure remains low after replacement of filter elements, remove all lube oil pressure gauges for calibration and re-install. Start engine and re-check oil pressure, if still abnormal continue investigation.

9.b PROBABLE CAUSE: OIL TEMPERATURE TOO HIGH.

9.b CORRECTION: Check temperature differential across the lube oil cooler and for adequacy of coolant flow. Adjust by-pass valve or temperature regulating valve as needed to reduce oil temperature to normal level.

9.c PROBABLE CAUSE: LUBE OIL LEAKAGE.

9.c CORRECTION: Inspect lube oil system for loose connections, defective gaskets, leaking flanges or worn oil seals. Tighten, repair or replace as necessary. Also check cooling water expansion tank or radiator for presence of oil. NOTE: In the event of internal leakage within the oil cooler, the oil, being at a somewhat higher pressure than the cooling water, will leak into the coolant and may be visible on the surface of the water within the expansion tank above the radiator or within the sight glass of an overhead expansion tank. If the leakage is severe enough the oil will probably emulsify and the coolant will appear milky. Should this type of leakage occur, the cooling water system should be completely drained. Disconnect and remove oil cooler and perform hydrostatic test to determine exact location of leakage and repair accordingly. A post-repair hydrostatic test should also be performed to determine adequacy of repair. Due to the possibility of cross-contamination after the engine is stopped, a sample of oil should be drawn off and examined for the presence of water. if the presence of water is evident the oil should be drained and run through a centrifugal purifier or safely disposed of. Upon completion of repairs both the lube oil system and the water cooling system should be flushed prior to being replenished and restored to service.

9.d PROBABLE CAUSE: WORN LUBE OIL PUMP.

9.d CORRECTION: Refer to SYMPTON No. 6, INSUFFICIENT LUBE OIL CIRCULATION. Read PROBABLE CAUSE ate and applicable CORRECTIONS.

9.e PROBABLE CAUSE: OIL DILUTED.

9.e CORRECTION: Determine cause of dilution and correct it. If the dilution is due to water, flush out the lubrication system, change oil and filter elements.

9.f PROBABLE CAUSE: DEFECTIVE PRESSURE REGULATING VALVE.

9.f CORRECTION: NOTE: Intermittent fluctuation of lube oil pressure is often attributable to dirt particles lodged between valve face and seat; and to a weak or broken valve spring. Refer to SYMPTOM No. 6, ENGINE KNOCKING NOISE. Read PROBABLE CAUSE "h" and applicable CORRECTIONS.

9.g PROBABLE CAUS[: DEFECTIVE OIL PRESSURE GAUGE.

9.g CORRECTION: Remove pressure gauge and test it with compressed air. Repair or replace as warranted.

9.h PROBABLE CAUSE: LOW OIL SUPPLY.

9.h CORRECTION: Check crankcase oil level and replenish as necessary.

9.i PROBABLE CAUSE: PRESSURE GAUGE SUPPLY LINE PLUGGED.

9.i CORRECTION: Disconnect oil pressure gauge supply line at both ends and drain residual oil. Tie a piece of rag over one end to contain oil spray and to trap the obstruction, then apply compressed air to the opposite end till the obstruction is blown out. Remove rag, inspect use of the obstruction and investigate source, if warranted. Apply compressed a1 to the line one more time before re-installing. Re-connect supply line but leave the connection to the pressure gauge loose. Prime the lubricating oil system to purge the pressure gauge supply line of air and when oil starts leaking at the gauge connection, tighten the connection.

9.j PROBABLE CAUSE: WORN ENGINE BEARINGS.

9.j CORRECTION: Check all main and connecting rod bearings for excessive wear and measure all main and crankpin bearing journals to determine extent of wear down. If crankshaft wear down is within tolerance, polish journals and install new bearings. If manufacturer's allowable wear down limits are exceeded, try to determine feasibility of having bearing journals ground to accommodate under¬size bearings. If not, a new crankshaft should-be installed with all new bearings.

10. SYMPTOM: EXCESSIVE OIL CONSUMPTION.

10.a PROBABLE CAUSE: EXTERNAL LEAKAGE.

10.a CORRECTION: Inspect lube oil system for loose pipe connections, defective gaskets and leaking crankshaft or camshaft oil seals. Repair or replace as warranted. Check for high crankcase pressure. Refer to SYMPTON No. 16, EXCESSIVE CRANKCASE BLOW-BY. Read PROBABLE CAUSES "a" and "b" and applicable CORRECTIONS.

10.b PROBABLE CAUSE: LEAKING SCAVENGE BLOWER SEALS.

10.b CORRECTION: Inspect scavenge air trunk for presence of oil and if observed, remove scavenge air blower intake screen. Inspect scavenge air blower housing end plates for signs of oil leakage radiating from oil seals. If leakage is severe, scavenge air blower bearings may also be worn. Remove blower, disassemble and repair or replace oil seals, gaskets, and bearings as warranted.

10.c PROBABLE CAUSE: LEAKING OIL COOLER.

10.c CORRECTION: Refer to SYMPTON No. 9, LOW ENGINE OIL PRESSURE. Read PROBABLE CAUSE "c" and applicable CORRECTIONS.

10.d PROBABLE CAUSE: IMPROPER GRADE OF OIL.

10.d CORRECTION: Take samples of oil and send to laboratory for analysis. Compare results with engine manufacturer's recommended lube oil specifications. Replace suspect oil accordingly and replace oil filter elements.

10.e PROBABLE CAUSE: WORN PISTON RINGS.

10.e CORRECTION: Take compression readings and measure liner wear down for comparison with manufacturer's allowable limits. If liner wear down is within tolerance, hone liners to remove glaze and replace all piston rings with new standard size if feasible, or with over-size rings if warranted. If wear down is excessive, replace liners and piston rings. Also inspect crankshaft and camshaft bearings for wear down and replace as warranted.

10.f PROBABLE CAUSE CAUSE: BADLY WORN VALVE GUIDES.

10.f CORRECTION: Intercept the exhaust effluent reasonably close to the stack with a clean sheet of paper to capture droplets of unburned oil. Refer to SYMPTON No. 4, ENGINE OVERSPEEDS. Read PROBABLE CAUSE "c" and note reference to worn exhaust valve guides. After confirming the presence of oil in the exhaust, stop the _engine and remove the exhaust manifold. Inspect the exhaust port of each cylinder head to determine the source of fugitive oil and remove the suspect cylinder head. Remove the exhaust valve and guide for inspection of wear down in the valve guide bore, also check exhaust valve stem for indications of wear. Install new valve guide and replace the exhaust valve if warranted. NOTE: This condition is usually the result of improper valve lapping during cylinder head overhaul. If excessive lapping compound is used it tends to migrate down to the annular space between the valve stem and valve guide bore. Unless the valve and guide are wiped clean before re-assembly, subsequent valve motion will tend to grind the valve guide bore.

11. SYMPTON: ENGINE OVERHEATS.

11.a PROBABLE CAUSE: ENGINE OVERLOADED.

11.a CORRECTION: Refer to SYMPTON No. 2, ENGINE STOPS SUDDENLY. Read PROBABLE CAUSE "c" and applicable CORRECTION. Also, re-check cooling water discharge temperature at each cylinder after cause of overload has been corrected. Re-check lube oil and exhaust temperatures also.

11.b PROBABLE CAUSE: INADEQUATE COOLING.

11.b CORRECTION: If the cooling system is of the two-phase flow, water-to-water type, check the raw water or sea water circulating pump for proper operation and associated suction strainers for possible blockage. Check coolant level in expansion tank and refill as needed. If expansion tank water level drops quickly, add coloring dye to check heat exchanger for possible internal leakage by observing raw water or sea water overboard discharge. Check jacket water circulating pump for proper operation and thermostatic control valve for correct setting. Check radiator (if applicable) for signs of blockage to air flow and fan belts for proper tension. Check entire cooling system for indications of external leakage. Inspect crankcase oil for signs of emulsification, indicative of cylinder jacket seal leakage. Accomplish all repairs as required.

11.c PROBABLE CAUSE: SCALE IN COOLING SYSTEM.

11.c CORRECTION: Drain cooling system and flush out with manufacturer's recommended scale solvent solution, followed by an alkaline solution flush. Refill cooling system with fresh coolant and add a zeolite type water softener and an alkaline chromate to raise coolant water pH value to 8 or more. Consult a water treatment engineer for correct dosage to suit the type of water in any given area.

11.d PROBABLE CAUSE: CRACKED CYLINDER HEAD OR LINER.

11.d CORRECTION: Refer to SYMPTON No. 1, ENGINE FAILS TO START OR IS DIFFICULT TO START. Read PROBABLE CAUSE “i” and applicable CORRECTIONS. Remove suspect cylinder head and prepare for a hydrostatic pressure test to locate area of suspected crack. Perform a hydrostatic test of the cooling water passages at not more than twenty percent above the normal jacket water operating pressure. Clearly mark cracked area for subsequent repair. If cylinder liner is cracked, remove and replace with a new liner and new neoprene seal.

11.e PROBABLE CAUSE: WATER PUMP FAILURE.

11.e CORRECTION: Repair or replace water pump as required and monitor performance.

11.f PROBABLE CAUSE: THERMOSTATIC CONTROL VALVE FAILURE.

11.f CORRECTION: In the case of small engines, remove the thermostat valve and place same in a bucket of hot water, not less than 200°F, and watch closely. If thermostat fails to open it should be replaced with a new one. For large engines equipped with the type of thermostatic control valve featuring a sensing element and capillary tube, an operational test can be performed by temporarily disconnecting the sensing element from the piping system and immersing it in a bucket of hot water, not less than 180°F, while observing the valve stem which should rise to open the valve. Most of these types of valves are manually adjustable for different temperature settings. In the event the thermostatic control valve fails to respond to adjustment, it should be replaced.

12. SYMPTON: EXHAUST TURBO-CHARGER OVERHEATS.

12.a PROBABLE CAUSE: ENGINE EXHAUST TEMPERATURE TOO HIGH.

12.a CORRECTION: Determine cause of high exhaust temperature and correct it. Refer to SYMPTON No. 8, EXHAUST TEMPERATURE TOO HIGH. Read PROBABLE CAUSES "a" through “e” and applicable CORRECTIONS. After problem has been corrected, monitor exhaust temperatures of all cylinders for stability.

12.b PROBABLE CAUSE: INADEQUATE COOLING.

12.b CORRECTION: Determine if cause of inadequate turbo-charger cooling is due to low coolant flow, clogged coolant supply pipe, scale formation within turbo-charger coolant spaces or to a problem within the engine cooling system. Check the lube oil supply line for adequacy of flow as the oil not only lubricates the turbo-charger bearings but also absorbs a certain amount of heat. NOTE: Also check the turbo-charger air intake screen for possible obstruction that may cause a reduced air intake flow. Although this would result in a correspondingly lower volume of exhaust gas entering the turbine chamber, the reduced air flow into the turbo-charger compressor compartment would also absorb less heat radiating from the turbine chamber. Implement applicable corrective measures.

13. SYMPTON : ENGINE EMITTING BLACK SMOKE.

13.c PROBABLE CAUSE: INCOMPLETELY BURNED FUEL.

13.c CORRECTION: Check exhaust system for possible back pressure and correct as required. Check engine air intake system for possible obstruction, including air intake suction screens, air intake filters and air intake manifold. Also inspect scavenge air blower intake screen, turbo charger air intake screen, air intake valves and restricted scavenge air ports. Check operating condition of exhaust turbo-charger and/or scavenge air blower. Check exhaust temperature of each cylinder for indications of high readings. Verify timing of fuel injectors. Adjust, repair or replace as warranted and re-start engine. If sympton continues Remove all fuel injectors, test each one for correct injection pressure and check condition of atomizer nozzle tip. Adjust, repair or replace as warranted.

14. SYMPTON: ENGINE EMITTING_BLUE SMOKE.

14.a PROBABLE CAUSE: LUBE OIL ENTERING COMBUSTION CHAMBER.

14.a CORRECTION: Refer to SYMPTON No. 4, ENGINE OVERSPEEDS. Read PROBABLE CAUSE "c" and applicable CORRECTIONS. Also check the air intake filter oil bath for proper oil level. If the level is above normal oil may be carried over into the cylinders. Perform repairs as required.

15. SYMPTON: ENGINE EMITTING WHITE SMOKE.

15.a PROBABLE CAUSE: ENGINE IS TOQ COLD.

15.a CORRECTION: Refer to SYMPTON No. 1, ENGINE FAILS TO START OR IS DIFFICULT TO START. Read PROBABALE CAUSE "e" and applicable CORRECTIONS.

15.b PROBABLE CAUSE: MISFIRING CYLINDERS.

15.b CORRECTION: Refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSE "f" and applicable CORRECTIONS. NOTE: This condition may also be attributable to the use of a low cetane fuel. Submit a sample of the fuel to a laboratory and compare results with engine manufacturer's recommendations for fuel characteristics and grade.

16. SYMPTON: EXCESSIVE CRANKCASE PRESSURE.

16.a PROBABLE CAUSE: CYLINDER BLOW-BY.

16.a CORRECTION: Take comparative compression readings and re-check cylinder with lowest reading. With engine stopped, jack engine over until the suspect cylinder piston is at top dead center on the compression stroke. Connect a small stop valve and a pressure gauge to an air hose attached to a rubber nozzle that will fit snugly into the indicator cock (if available) if not, remove the fuel injector and insert the rubber nozzle into the opening in the cylinder head. Apply low air pressure (not to exceed 20 p.s.i.) to the cylinder and close the stop valve. Remove crankcase oil dip stick to determine if compressed air is blowing by the piston rings and escaping into the crankcase. Repeat this test on all cylinders and monitor the elapsed time for the pressure to dissipate from each cylinder. The time lapse will be inversely proportional to the extent of piston ring wear.

16.b PROBABLE CAUSE: CLOGGED CRANKCASE BREATHER.

16.b CORRECTION: Remove, clean and inspect crankcase breather and vent tube, if applicable. Repair, reinstall or replace as warranted. Re-check crankcase pressure.

16.c PROBABLE CAUSE: AIR LEAKAGE FROM SCAVENGE BLOWER.

16.c CORRECTION: Inspect scavenge air blower-to-block mounting for leaking gasket, loose bolts, etc. Also check blower housing end plates for cracks where air pressure might enter the rotor drive gear housing and engine gear train compartment and into the crankcase. Repair or replace as warranted.

16.d PROBABLE CAUSE: DILUTED LUBE OIL.

16.d CORRECTION: Determine cause of dilution and correct it. If the oil appears to be emulsified, the cause is probably due to a jacket water leak, which should be investigated further and corrected. Also flush out the lubrication system, change the oil and filter elements. NOTE: If the dilution is due to a fuel leak, the hot oil will cause the fuel to vaporize and build up pressure in the crankcase that could become explosive. Check high pressure fuel lines leading to the injectors for possible leakage and tighten all fuel line connections. Change the lube oil and lube oil filters.

16.e PROBABLE CAUSE: LUBE OIL TOO HOT.

16.e CORRECTION: NOTE: Hot lube oil will also vaporize and raise crankcase pressure. If possible, note temperature differential across the lube oil cooler and check for adequacy of coolant flow through cooler. If the cooler is equipped with either a by-pass valve or temperature regulating valve, adjust as needed to restore oil temperature to normal level.

17. SYMPTON: CYLINDER SAFETY VALVE POPS FREQUENTLY.

17.a PROBABLE CAUSE: EXCESSIVE AMOUNT OF FUEL INJECTED.

17.a CORRECTION: Check exhaust temperature of all cylinders. Double-check the one with the popping safety valve. If excessive fuel injection is suspected, and confirmed by relatively higher exhaust temperature, remove injector for inspection and install a replacement injector. Connect suspect injector to a test pump and test for correct injection pressure, proper spray pattern and possible atomizer nozzle leakage. Excessive injection volume may be the result of failure of the nozzle needle valve to close properly, low injection pressure setting or a faulty injector spring. Repair faulty injector as warranted and re-calibrate.

17.b PROBABLE CAUSE: DEFECTIVE SAFETY VALVE.

17.b CORRECTION: Take and record firing pressures on all cylinders along, with corresponding exhaust temperatures, prior to making any adjustments to the suspect safety valve. If firing pressures are normal, repair or replace the suspect safety valve. If firing pressures are found to be excessive, determine the probable cause and correct it.

18. SYMPTON: ENGINE WILL NOT SHUT OFF.

18.a PROBABLE CAUSE: INJECTION PUMP RACK STUCK.

18.a CORRECTION: Check control shaft linkage and disengage the rack of any fuel injection pump found to be stuck, then stop the engine in the normal manner. Repair or replace any stuck rack and operate throttle lever to verify that all fuel injection pump racks move freely in and out. For multiple pump mono-block units, with a single rack for all pumps elements, move the rack to the shut off position. If the rack will not move freely, disconnect the fuel supply line to the pump and allow the engine to stop. Repair the fuel injection pump rack mechanism or replace the entire pump.

18.b PROBABLE CAUSE: EXCESSIVE LUBE OIL REACHING COMBUSTION CHAMBER FROM SCAVENGE AIR BLOWER.

18.b CORRECTION: Close emergency shut-off flapper valve to blower intake, or discharge a CO2 fire extinguisher into the blower to stop the engine.

19. SYMPTON: ENGINE EMITTING SMOKE FROM CRANKCASE

19.a PROBABLE CAUSE: SEIZED MAIN OR CONNECTING ROD BEARING.

19.a CORRECTION: Shut off engine and allow to cool off for at least thirty minutes before opening crankcase inspection doors. When safe to do so, inspect all main and connecting rod bearings to locate the affected bearing and to determine over-all condition and cause of seizure. Check for clogged lube oil passages, loose or broken oil pipes, presence of foreign particles in the oil or any other indications of lubrication failure. After cause of seizure has been established, all bearing journals should be polished clean and smooth and measured with a micrometer to determine if they are still within allowable wear limits for standard size bearings. If so, all existing bearings can be re-used with the exception of that which was seized, and for which a new replacement bearing will be required. Flush out the lubrication system thoroughly and with the use of an external service pump, apply oil pressure to the crankshaft only, to ensure that all crankshaft internal oil passages are clear. Re-assemble all crankshaft bearings and torque to engine manufacturers specification. Drain the crankcase, wipe it clean and re-inspect carefully before replenishing lube oil. Replace all lube oil filter elements and prime the lubrication system thoroughly before starting the engine.

19.b PROBABLE CAUSE: BLOW-BY CAUSED BY WORN PISTON RINGS OR CYLINDER LINER.

19.b CORRECTION: Refer to SYMPTON No. 10, EXCESSIVE OIL CONSUMPTION.Read PROBABLE CAUSE "e" and applicable CORRECTIONS.

19.c PROBABLE CAUSE: LUBE OIL TOO HOT.

19.c CORRECTION: Refer to SYMPTON No. 16, EXCESSIVE CRANKCASE PRESSURE. Read PROBABLE CAUSE "e" and applicable CORRECTIONS.

20. SYMPTON: SUDDEN LOUD NOISE FOLLOWED BY SMOKE EMANATING FROM CRANKCASE.

20.a PROBABLE CAUSE: CRANKCASE EXPLOSION.

20.a CORRECTION: If a crankcase explosion is detected or suspected extreme caution should be exercised in coping with the incident to avoid further injury or damage. Since the presence of explosive vapors in the crankcase may lead to a secondary explosion if allowed to mix with fresh oxygen, the engine room or machinery compartment should be evacuated immediately and well ventilated for at least thirty minutes. Unless the engine has shut itself off it should be stopped immediately, by normal means if possible. If not, by using a fire extinguisher to flood the engine room or machinery compartment with CO2. No attempt should be made to re-enter the engine room until the atmosphere has been tested and determined to be safe for normal breathing without a respirator.

NOTE: Casualty occurrences involving crankcase explosions should be reported to the competent authority such as the local Fire Department and/or the U.S. Coast Guard, and to the pertinent insurance office as applicable, for investigation and recommended corrective action. Meanwhile, no repairs should be attempted pending completion of the investigation and issuance of proper authorization.

8.a PROBABLE CAUSE: ENG(NE OVERLOADED.

8.a CORRECTION: Refer to SYMPTON No. 2, ENGINE STOPS SUDDENLY. Read PROBABLE CAUSE "c" and applicable CORRECTIONS. Also re-check exhaust temperatures at each cylinder after correction of overload and re-check cooling water discharge from each cylinder and tube oil cooler outlet temperature.

8.b PROBABLE CAUSE: POOR GRADE OF FUEL.

8.b CORRECTION: Refer to SYMPTON No. 3, ENGINE LACKS POWER, SPEED IS UNSTABLE. Read PROBABLE CAUSE "b" and applicable CORRECTIONS.