Yanmar 6LY2-STE troubleshooting: 16 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Yanmar 6LY2-STE — full specs, parts & maintenance.
| Symptom | Cause | Remedy |
|---|---|---|
| Exhaust gas is dense | Insufficient amount of suction air | Air cleaner element is clogged. © Replace or clean the element. Air take-in port is blocked up. © Remove obstruction. Air leaks at pipe connection. © Check and repair the pipe. |
| Supercharger does not operate | Impurities contained in oil precipitate at seal of turbine and hamper smooth rotation of turbine shaft.; Seizure of metal; Insufficient oil feed or clogging of pipe; Too high oil temperature; Imbalance in rotating part; Insufficient warm-up operation or abrupt stopping of operation under load (No-load operation) | 1) Impurities contained in oil precipitate at seal of turbine and hamper smooth rotation of turbine shaft. © Change the engine oil and disassemble and clean the turbocharger. 2) Seizure of metal © Disassemble and repair the turbocharger. 3) Insufficient oil feed or clogging of pipe © Check the engine oil system, and repair the trouble spot and at the same time change the oil. 4) Too high oil temperature © Check the engine oil system, and repair the trouble spot and at the same time change the oil. 5) Imbalance in rotating part © Replace or clean the rotating part. 6) Insufficient warm-up operation or abrupt stopping of operation under load (No-load operation) © Observe the operating precautions described in the operation manual. |
| Effect of exhaust gas resistance | Rotating speed does not pick up due to exhaust gas leak before the turbocharger.; Turbocharger fails to increase its speed due to deformation or blocked deformation or exhaust gas pipe. | 1) Rotating speed does not pick up due to exhaust gas leak before the turbocharger. © Check the pipe connection and repair as required. 2) Turbocharger fails to increase its speed due to deformation or blocked deformation or exhaust gas pipe. © Repair the pipe to normal state. |
| Whitish exhaust gas | Oil flows into blower side or turbine side due to clogged or deformed oil return pipe.; Seal ring is worn abnormally or broken due to excessive metal abrasion. | 1) Oil flows into blower side or turbine side due to clogged or deformed oil return pipe. © Repair or replace the pipe. 2) Seal ring is worn abnormally or broken due to excessive metal abrasion. © Dissemble and repair the turbocharger. |
| Too early oil shortage | Seal ring is worn abnormally or broken due to excessive metal abrasion. | 1) Seal ring is worn abnormally or broken due to excessive metal abrasion. © Disassemble and repair the turbocharger. |
| Output drop | Gas leaks at part(s) in exhaust gas system.; Air leaks at discharge side of blower.; Clogging of air cleaner element.; Turbocharger is contaminated or damaged. | 1) Gas leaks at part(s) in exhaust gas system. © Disassemble and repair the turbocharger. 2) Air leaks at discharge side of blower. © Disassemble and repair the turbocharger. 3) Clogging of air cleaner element. © Clean or replace the element. 4) Turbocharger is contaminated or damaged. © Disassemble and repair or replace the turbocharger. |
| Poor follow-up of supercharger | Carbon deposits stuck on turbine side (wheel seal) hampers smooth rotation of turbine shaft.; Incomplete oil combustion. | 1) Carbon deposits stuck on turbine side (wheel seal) hampers smooth rotation of turbine shaft. © Change the engine oil and at the same time disassemble and clean the turbocharger. 2) Incomplete oil combustion. © Check the engine combustion system and restore its combustion state. |
| Unusual sound or vibration | If gas passage gets too narrow due to blockage of nozzle in turbine wheel chamber or gas flow speed is too fast, air discharged from blower is blocked and it flows reversely. (This phenomenon is generally called“surging”).; Rotating part is in contact.; Connection between turbocharge and suction or exhaust pipe or oil pipe is loosened.; Turbine wheel or blower wheel is broken due to trouble with metal, contact of rotating part with peripheral part(s) or entry of foreign matter.; Imbalance in rotating part(s). | 1) If gas passage gets too narrow due to blockage of nozzle in turbine wheel chamber or gas flow speed is too fast, air discharged from blower is blocked and it flows reversely. (This phenomenon is generally called“surging”). © Disassemble and clean the turbocharger. 2) Rotating part is in contact. © Disassemble and clean the turbocharger. 3) Connection between turbocharge and suction or exhaust pipe or oil pipe is loosened. © Check installation state of the turbocharger, and restore the loose part. 4) Turbine wheel or blower wheel is broken due to trouble with metal, contact of rotating part with peripheral part(s) or entry of foreign matter. © Disassemble and repair or replace the turbocharger. In the case of entry of foreign matter, remove it completely. 5) Imbalance in rotating part(s). © Repair or replace the rotating part(s). |
| The engine suddenly stops. | {1} Loose lube oil pressure adjustment valve. {2} Clogging of lube oil filter {3} Seizure of moving parts {4} Trouble with lube oil pump {5} Leakage from lube oil safety valve | {1-1} Tighten lube oil pressure adjustment valve. {1-2} Clean and replace if necessary. {1-3} Tighten or replace as needed. {1-4} Repair or replace. {1-5} Clean. |
| Uneven engine output. | {1} Clogged fuel injection pump {2} Faulty operation of plunger {3} Damaged plunger spring {4} Irregular injection timing {5} Carbon deposit in exhaust system | {1-1} Bleed air. {1-2} Disassemble and clean or replace as needed. {1-3} Adjust or replace. {1-4} Adjust or replace. {1-5} Clean. |
| Faulty operation of injection valve | (1) Uneven supply of fuel oil injected (2) Faulty operation of the pump plunger (5) Clogging of fuel biter (1) Impediment to valve needle movement (2) Damaged fuel pump plunger (6) Damaged fuel cam (4) Inaccurate assembly of fuel injection pump | |
| Faulty operation of governor | (1) Faulty operation of the governor (2) Sticking of governor sleeve (3) Seizure of moving parts (4) Faulty operation of the oil adjustment rack (5) Miscellaneous | |
| Rotation is not smooth | (1) Damaged governor bearing (2) Overloading (3) Sticking of governor sleeve (2) Seizure of moving parts (4) Faulty operation of the oil adjustment rack (5) Miscellaneous | |
| Knocking | (1) Excessive quantity of fuel is ejected from the pump (2) Excess piston clearance (3) Excess bearing clearance (4) Incorrect pressure (5) Excessive quantity of fuel injected each time (6) Miscellaneous | |
| Starting trouble | (1) Pinion gears do not mesh (2) Ring gears do not mesh (3) Faulty fuel injection valve (4) Loose battery engage magnet terminal (5) Edges of gear teeth (6) Faulty connection in misshapen starting switch (7) Seizure of starter metal (8) Rough cap movement (9) Loose battery (10) Faulty connection in (11) Fuel oil not injected (12) Cut starter coil (13) Insufficient fuel air in tank (14) Fuel oil tank cock closed (15) Clogging of fuel injection filter (16) Air inside pump (17) Air leakage from suction/exhaust valves (18) No tappet clearance (19) Incorrect thickness of gasket (20) Upper part of cylinder liner worn (21) Worn piston ring (22) Damaged high pressure fuel pipe (23) Oil leakage from exhaust valve (24) Damaged exhaust valve spring (25) Air in high pressure fuel pipe (26) Insufficient lightening of head bolts (27) Faulty installation of governor | |
| Insufficient power output | (1) Clogged nozzle hole or replace (2) Disassemble and repair or replace (3) Lap or replace (4) Tighten firmly |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Insufficient amount of suction air. See the table for the matching fixes.
Documented causes: Impurities contained in oil precipitate at seal of turbine and hamper smooth rotation of turbine shaft.; Seizure of metal; Insufficient oil feed or clogging of pipe; Too high oil temperature; Imbalance in rotating part; Insufficient warm-up operation or abrupt stopping of operation under load (No-load operation). See the table for the matching fixes.
Documented causes: Rotating speed does not pick up due to exhaust gas leak before the turbocharger.; Turbocharger fails to increase its speed due to deformation or blocked deformation or exhaust gas pipe.. See the table for the matching fixes.