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Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP Engine

The Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP is a 6-cylinder turbocharged (rhc7w) engine rated at 3300 rpm. It powers generator sets from Yanmar, including the 6LY2-STE. It holds 20 L (5.3 gal) of coolant.

Also known as: YANMAR 6LY2-STE/6LY2A-STP/6LYA-STP

Cylinders

3300 rpm

Rated speed

On this pageSpecs Generator sets Maintenance FAQ Service intervals Torque & specs Fluids Procedures

Engine specifications

Coolant capacity	20.0 L
Cylinders	6
Aspiration	Turbocharged (RHC7W)
Rated speed	3300 rpm

Generator sets powered by this engine

Yanmar 6LY2-STE

How to read your Yanmar engine serial & model number →

Common problems

Whitish exhaust gas
Cause: 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.
Fix: 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.
Unusual sound or vibration
Cause: 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).
Fix: 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).
Uneven engine output.
Cause: {1} Clogged fuel injection pump {2} Faulty operation of plunger {3} Damaged plunger spring {4} Irregular injection timing {5} Carbon deposit in exhaust system
Fix: {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.
Too early oil shortage
Cause: Seal ring is worn abnormally or broken due to excessive metal abrasion.
Fix: 1) Seal ring is worn abnormally or broken due to excessive metal abrasion. © Disassemble and repair the turbocharger.
The engine suddenly stops.
Cause: {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
Fix: {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.
Supercharger does not operate
Cause: 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)
Fix: 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.
Starting trouble
Cause: (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
Rotation is not smooth
Cause: (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
Poor follow-up of supercharger
Cause: Carbon deposits stuck on turbine side (wheel seal) hampers smooth rotation of turbine shaft.; Incomplete oil combustion.
Fix: 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.
Output drop
Cause: 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.
Fix: 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.
Knocking
Cause: (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
Insufficient power output
Cause: (1) Clogged nozzle hole or replace (2) Disassemble and repair or replace (3) Lap or replace (4) Tighten firmly
Faulty operation of injection valve
Cause: (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
Cause: (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
Exhaust gas is dense
Cause: Insufficient amount of suction air
Fix: 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.

Compiled from service & troubleshooting documentation across every generator set that uses the Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP.

Maintenance schedule

Item	Part #	Interval
Air filter	—
Fuel filter	—
Oil filter	—
Battery	—
Belt	—
Coolant	—
Oil	—	250 hr
Spark plug	—

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Lube oil filter	Replace	250 hr		First service — First time 50 hrs
Fuel filter element	Replace	300 hr		Replace element every 300 hours of operation
Thermostat	Inspect	500 hr		Normally inspected every 500 hours
Oil filter	Replace	1000 hr		Marine gear; replace filter element every 1000 hrs
Rotor rotation	Check	1500 hr	6 mo	Turbocharger; every 6 months or 1500 operating hrs
Fuel injection timing	Check	2000 hr		Every 2000 service hrs
Thermostat	Replace	2000 hr	12 mo	Replace every year or 2000 hours, whichever comes first
Rotor play	Check	3000 hr	12 mo	Turbocharger; every 12 months or 3000 operating hrs
Oil cooler	Clean	5000 hr		Marine gear; clean inside of cooling pipe and cooler every 5000 hrs
Turbocharger entire supercharger	Inspect	6000 hr	24 mo	Disassembly, cleaning and checking; every 24 months or 6000 operating hrs
Rubber block	Check		24 mo	Marine gear; check for cracks and wear visually every 2 years

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Camshaft side gap	0.05~0.20	mm
Clearance	Connecting rod side clearance	0.20~0.40	mm
Clearance	Crank journal and bearing oil clearance	0.036~0.093	mm
Clearance	Crank pin and bearing oil clearance	0.036~0.093	mm
Clearance	Crankshaft side gap	0.132~0.223	mm
Clearance	Idle shaft and bushing oil clearance	0.025~0.075	mm
Clearance	Piston pin and bearing oil clearance	0.030~0.061	mm
Clearance	Rotor axial play	0.06~0.09	mm	maintenance standard; limit 0.110 mm
Clearance	Rotor radial play	0.11~0.18	mm	maintenance standard; limit 0.215 mm
Clearance	Top clearance	0.70~0.90	mm
Clearance	Top clearance	0.71~0.89	mm
Clearance	Valve rocker arm shaft and bushing clearance	0.012~0.061	mm	at assembly
Injection timing	Fuel injection timing	13°±1°	bTDC	FID
Injection timing	Fuel injection timing	15°±1°	bTDC	FID
Pressure	Nozzle opening pressure	25.5~26.5	MPa	260~270 kgf/cm²
Pressure	Nozzle opening pressure	28.4~29.4	MPa	290~300 kgf/cm²
Pressure	Oil pressure regulating valve setting pressure	0.490±0.049	MPa	3000 rpm, oil temp 85°C
Speed	High idling	3720±25	rpm
Speed	Low idling	700±25	rpm
Temperature	Thermostat full open temperature	85	°C
Temperature	Thermostat valve open temperature	71±2	°C
Torque	Connecting rod bolt	13.5~14.5	kgf·m
Torque	Crank V-pulley bolt	226±10	N·m
Torque	Cylinder head bolts	118 / 177 / 216~236	N·m	First / Second / Final
Torque	Cylinder head bolts	12 / 18 / 22.0~24.0	kgf·m	First / Second / Final
Torque	Exhaust manifold bolt	25±2	N·m
Torque	Flywheel bolt	294±10	N·m
Torque	Main bearing cap bolt	25~27	kgf·m
Torque	Metal cap bolt	255±10	N·m
Torque	Nozzle nut	10~12	N·m
Torque	Nozzle nut	3.9~4.9	N·m
Torque	Rod bolt	137±4.9	N·m
Torque	Timer nut	127±10	N·m
Torque	Turbocharger V-band	8.8	N·m	final
Valve clearance	Exhaust valve clearance	0.5	mm	cold
Valve clearance	Exhaust valve clearance	0.5±0.03	mm	cold
Valve clearance	Intake valve clearance	0.1	mm	cold
Valve clearance	Intake valve clearance	0.1±0.03	mm	cold

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Ambient	Capacity	Notes
Coolant		Fresh water with Yanmar anti-rust agent; antifreeze in cold areas	below 5°C	20.0 L	Cooling water capacity; subtank capacity 1.5 L
Engine oil		Use only lube oil recommended by Yanmar			Engine lube oil capacities vary by model
Fuel	Diesel	Density at 15°C = 0.860; fuel oil temperature 25°C at fuel injection pump inlet
Hydraulic oil	API Service grade CD (#30)			4.0 L	Marine gear KMH6A1 full capacity; effective 0.3 L

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Fuel injection nozzle adjustment adjustment

Tools: Nozzle tester

Mount fuel injection nozzle on nozzle tester.
Measure injection starting pressure.
Adjust with shims to specified pressure.
Check seat oil tightness.
Check spray condition.

Valve clearance adjustment adjustment

Tools: Feeler gauge, Wrench

Adjust when engine is cool.
Measure intake clearance 0.1 mm and exhaust clearance 0.5 mm.
Loosen lock nut and turn adjusting screw.
Tighten lock nut.
Recheck clearance.

Fuel injection timing check and adjustment diagnostic

Remove high-pressure fuel pipe from fuel injection pump.
Turn flywheel slowly by hand.
Check fuel flow from delivery valve holder at specified timing.
Check all cylinders.
To advance timing, incline pump away from engine.

Fresh water pump inspection maintenance

Tools: Thickness gauge, Straight edge

Rotate impeller smoothly; replace pump if not smooth or abnormal noise.
Check impeller blade for damage or corrosion.
Clean cooling water and bypass holes.
Measure clearance between impeller and body: 0.3~1.1 mm.
Measure clearance between impeller and plate.

Lube oil filter replacement maintenance

Tools: Filter wrench

Remove lube oil filter with filter wrench.
Clean filter mounting surface.
Coat rubber packing with lube oil.
Screw in until packing contacts, tighten about 3/4 turn.
Run engine and check for oil leakage.

Thermostat testing maintenance

Tools: Thermometer

Put thermostat in breaker with fresh water.
Heat on electric stove.
Check starts to open between 69.5~72.5°C.
Check opens 8 mm or more at 85°C.
Replace if not functioning normally.

Cylinder head assembly repair

Tools: Torque wrench

Clean bolt holes and cylinder head surface.
Coat head bolt threads and nut seats with lube oil.
Install head gasket with positioning pins.
Mount cylinder head.
Tighten bolts in specified order.
First 118 N·m, second 177 N·m, final 216~236 N·m.

Fuel injection pump disassembly repair

Tools: Box spanner, Screwdriver

Wash outside of pump.
Remove governor weight assembly.
Remove fuel feed pump.
Remove camshaft woodruff key.
Remove bearing holder bolts.
Pull out camshaft bearing holder.
Remove camshaft.
Remove roller guide parts.
Remove control rack.
Remove delivery valve holder.
Remove delivery valve assembly.
Remove plunger barrel.

Governor disassembly repair

Tools: Needle-nosed pliers, Box spanner, Wooden hammer

Remove governor case cover.
Remove angleich spring assembly.
Remove governor case bolts.
Remove connecting spring.
Pull out link pin of fuel control rack.
Remove governor lever shaft.
Remove governor weight assembly.

Sea water pump disassembly repair

Tools: Pliers

Remove rubber hose and pump assembly.
Remove cover and take out O-ring, impeller, wear plate.
Remove mechanical seal side stop ring.
Remove bearing stop ring.
Tap out pump shaft, bearings, drive gear.
Remove oil seal and mechanical seal.

Turbocharger disassembly repair

⚠ Shaft end nut has left-hand thread

Tools: Box wrench 14 mm, TORX screwdriver, Copper bar, Stop ring pliers

Mark match marks on housings.
Disconnect boost hose.
Remove blower wheel chamber.
Remove shaft end nut (left-hand thread) and blower wheel.
Remove turbine housing.
Remove turbine shaft.
Remove seal plate.
Remove thrust bearing and thrust bush.
Remove floating metal.
Remove seal rings.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

Which generators use the Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP engine?

The Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP powers 1 generator set(s), including Yanmar 6LY2-STE.

How often should you change the oil in the Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP?

The Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP oil change interval is every 250 hours.

What is a common problem with the Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP engine?

A commonly reported issue on generators using the Yanmar 6LY2-STE/6LY2A-STP/6LYA-STP is: Whitish exhaust gas. Cause: 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.. Fix: 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..