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Mitsubishi PS6 Engine

The Mitsubishi PS6 is a 24.5 L 6-cylinder turbocharged - with aftercooler engine. It powers generator sets from Mitsubishi, including the S6R S6R2.

Also known as: Mitsubishi PS6

Part of the Mitsubishi PS6 engine family — 2 variants share parts & fitment.

24.5 L

Displacement

Cylinders

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

Engine specifications

Displacement	24.5 L
Cylinders	6
Aspiration	turbocharged - with aftercooler

Generator sets powered by this engine

Mitsubishi S6R S6R2

How to read your Mitsubishi engine serial & model number →

Common problems

Engine lacks power
Cause: Oil viscosity incorrect
Fix: Change oil.
White or blue exhaust smoke
Cause: Too much oil in engine
Fix: Maintain correct oil level.
Black exhaust smoke
Cause: Bad quality fuel
Fix: Change fuel.
Low oil pressure
Cause: Not enough oil in engine
Fix: Refill up to specified level.
High fuel consumption
Cause: Fuel feed pump defective
Fix: Consult your Mitsubishi dealer.
High oil consumption
Cause: Too much oil in engine
Fix: Maintain correct oil level.
Engine overheats
Cause: Radiator and/or heat exchanger dirty
Fix: Clean or consult your Mitsubishi dealer.
Engine will not run (direct air type)
Cause: Air pressure low
Fix: Run air compressor to increase air pressure.
Air motor will not crank engine
Cause: Air pressure low
Fix: Run air compressor to increase air pressure.
Starter will not crank engine (electric start) — low oil pressure indicator ON
Cause: Battery-starter circuit open or shorted
Fix: Repair or replace.
Starter will not crank engine (electric start) — fuse blown
Cause: Fuse blown
Fix: Replace.
Starter will not crank engine (electric start) — battery discharged (electrolyte specific gravity low)
Cause: Battery discharged (electrolyte specific gravity low)
Fix: Recharge.
Starter will not crank engine (electric start) — battery dead
Cause: Battery "dead"
Fix: Check alternator drive belt.
Starter will crank engine, but engine will not start — water and sediment
Cause: Water and sediment
Fix: Drain.
Starter will crank engine, but engine will not start — muffler or exhaust pipe restricted
Cause: Muffler or exhaust pipe restricted
Fix: Consult your Mitsubishi dealer.

Compiled from service & troubleshooting documentation across every generator set that uses the Mitsubishi PS6.

Service intervals

Item	Action	Hours	Months	Notes
air filter	Drain	50 hr		General duty - every 50 service hours or monthly - drain water
air tank	Drain	50 hr	1 mo	General duty - every 50 service hours or monthly
bolts and nuts	Check	50 hr		First service — Every 50 service hours or monthly - the first 50 service hours of new or reconditioned engine (generator set prime power)
fuel tank water and sediment	Drain	50 hr		First service — Generator set prime power
V-belt	Adjust	250 hr	12 mo	General duty - every 250 service hours or 1 year
air tank safety valve	Check	250 hr	12 mo	General duty - every 250 service hours or 1 year
engine oil	Change	250 hr	24 mo	First service — Oil analysis is recommended
full-flow filter and bypass filter	Change	250 hr	24 mo	First service — The filters must also be changed when oil filter indicator light comes ON
radiator fins	Clean	250 hr	48 mo	General duty - every 250 service hours or 1 year
valve clearance	Adjust	2000 hr	12 mo	First service — The first 250 service hours of new or reconditioned engine; check valve mechanism
air filter	Clean	1000 hr	24 mo	General duty - every 1000 service hours or 2 years - wash
zinc rods	Change	1000 hr	24 mo	General duty - every 1000 service hours or 2 years
V-belts	Change	2000 hr
bolts and nuts	Other	2000 hr	36 mo	General duty - retighten; refer to SERVICE MANUAL for tightening torques
fuel control link ball joints	Check	2000 hr		Change if necessary
fuel filter (cartridge type)	Change	2000 hr	36 mo	General duty - every 2000 service hours or 3 years
fuel injection pump (governor) rack movement	Check	2000 hr		During operation
injection nozzle tips	Change	2000 hr		Adjust injection pressure after replacement
air cooler	Clean	4000 hr	60 mo	General duty - every 4000 service hours or 5 years
heat exchanger	Clean	4000 hr	60 mo	General duty - every 4000 service hours or 5 years - wash
top overhaul	Other	4000 hr		Every 4000 to 6000 service hours; remove cylinder heads, check valves and seats, piston tops, cylinder liners, change water pump seals
vibration damper	Check	4000 hr	60 mo	General duty - every 4000 service hours or 5 years
major overhaul	Other	8000 hr		Every 8000 to 12000 service hours; disassemble engine, wash, check and change major parts
LLC concentration in coolant	Check		6 mo	Every 6 months
V-belts	Adjust	1000 hr	12 mo	Every 1 year - check
air cleaner element	Change		48 mo	Every 4 years
air cleaner element	Clean		12 mo	Every 1 year - check
air compressor	Other		24 mo	Every 2 years - overhaul
alternator	Check		12 mo	Every 1 year
battery electrolyte level	Check		1 mo	Standby duty - monthly
bypass oil filter	Change	250 hr	24 mo	Every 2 years
coolant	Change		24 mo	Every 2 years
coolant tank inside	Clean		6 mo	Every 6 months - wash
fuel control link	Check		1 mo	Standby duty - monthly
fuel control link ball joints	Change		24 mo	Every 2 years
fuel filter (wire element type)	Clean		1 mo	Turn handle one or two times
fuel injection nozzle tips	Change		96 mo	Every 8 years
fuel or water in oil	Check		1 mo	Standby duty - monthly
hydraulic governor oil filter	Change	250 hr	48 mo	Every 4 years
injection nozzle discharge pattern and injection pressure	Adjust		12 mo	Every 1 year

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	Battery electrolyte level above plates	10 to 15	mm
Clearance	Clearance between valve bridge and valve rotator	1.5	mm	minimum
Clearance	Fuel control link ball joint play	0.1	mm	change ball joints if more than this
Gap	V-belt deflection	10 to 15	mm	apply approximately 98 to 147 N (10 to 15 kgf) force midway between pulleys
Pressure	Air cleaner dust indicator differential pressure	635	mmH2O	element clogged when greater - clean element
Pressure	Air cleaner element cleaning maximum air pressure	0.69	MPa
Pressure	Air tank pressure (air motor type)	0.97	MPa	before starting
Pressure	Air tank pressure (direct air type)	2.94	MPa	before starting
Pressure	Air tank safety valve opening pressure (air motor type)	0.97	MPa
Pressure	Air tank safety valve opening pressure (direct air type)	3.14	MPa
Pressure	Engine oil pressure	0.20 to 0.29	MPa	after warm-up run
Pressure	Engine oil pressure	0.39 to 0.64	MPa	after warm-up, when SAE 30 engine oil is used
Pressure	Engine oil pressure (minimum at rated speed)	0.29	MPa	at rated speed - stop engine if lower
Pressure	Fuel injection start pressure	34.32	MPa	standard value
Pressure	Low oil pressure indicator light set point	0.15 ± 0.02	MPa	entire speed range
Pressure	Low oil pressure indicator light set point	0.29	MPa	engine speed higher than 1500 rpm
Pressure	Oil filter indicator differential pressure	0.15	MPa	replace oil filter when light comes ON
Temperature	Coolant temperature gauge normal reading	65 to 85	°C	ambient temperature 20°C to 30°C
Temperature	High coolant temperature indicator light set point	95 ± 2	°C	at radiator inlet
Temperature	Viscous damper surface temperature	100	°C	standby-duty engine, max after one hour operation
Temperature	Viscous damper surface temperature	90	°C	generator set prime power, max after one hour operation
Temperature	Viscous-rubber damper surface temperature	80	°C	generator set prime power, max after one hour operation
Temperature	Viscous-rubber damper surface temperature	90	°C	standby-duty engine, max after one hour operation
Torque	Fuel injection nozzle retaining nut	186 ± 10	N-m	apply oil to the nut
Torque	Nozzle cap nut	74 ± 5	N-m
Torque	Nozzle gland nut	98 ± 5	N-m
Torque	Nozzle inlet connector	69 ± 5	N-m
Torque	Nozzle set screw	39 ± 5	N-m
Valve clearance	Exhaust valve clearance	0.8	mm	cold
Valve clearance	Inlet valve clearance	0.6	mm	cold
Voltage	Battery electrolyte specific gravity	1.26 - 1.28		at 20°C, fully charged
Voltage	Battery electrolyte specific gravity	below 1.22		at 20°C, discharged - recharge

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	LLC (all-season, non-amine type LLC)		above -45°C		Recommended concentrations: 30% at -10°C, 40% at -20°C, 50% at -30°C, 60% at -45°C; proper concentration 30% to 60%; change every 2 years; coolant capacity 50 L (S6R basic block) / 55 L (S6R2 basic block); recommended brands: Mitsubishi Oil Diamond Diesel Coolant, Mitsubishi Motors Fuso Diesel Long Life Coolant
Engine oil	SAE 15W-40 (Mitsubishi recommends all-season type); also SAE 30, SAE 40, SAE 10W-30, SAE 5W-20	Engine Service Classification CF		82.0 L	Oil pan 82 L, whole engine 92 L; do not use Class CF-4 when using heavy oil; avoid mixing oils of different brands
Fuel	Diesel fuel or heavy oil	JIS K 2204, 2205			Limiting Requirements for Diesel Fuel Oils: cetane number 45 min, sulfur 0.2% max (new limit) / 1.0% max (conventional); pour point should be at least 6°C below lowest atmospheric temperature
Other	Turbine oil ISO VG32				For the oiler of air-motor type; maintain oil level to FULL mark

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

Procedures

Adjust fuel injection timing adjustment

⚠ Do not confuse No. 1 cylinder with No. 6

Tools: Wrench

Make sure the timing mark on the caution plate is aligned with the pointer with the piston at TDC on compression.
Loosen two bolts for the fuel injection pump coupling.
Turn the coupling flywheel until its timing mark aligns with the pointer on the fuel injection pump.
Tighten one coupling bolt; turn the engine to tighten the other bolt and the opposite side nut.
Turn the engine two turns to recheck the injection timing.

Adjust the alternator drive belt adjustment

⚠ Change the belts if cracked, frayed or cut

⚠ Never adjust the V-belts while the engine is running

Remove the belt cover of the alternator.
Loosen the alternator mounting bolts.
Turn the adjusting rod to move the alternator to obtain the required belt deflection.
Tighten the alternator mounting bolts.

Check and adjust valve clearance adjustment

⚠ Adjust when the engine is cold

⚠ If bridge-to-rotator clearance is less than 1.5 mm after adjustment, consult your Mitsubishi dealer

Tools: Feeler gauge, Wrench

Turn engine in normal direction to align timing mark 1.6 on damper with the pointer.
Remove the rocker cover and confirm inlet and exhaust valves have clearance.
Loosen the lock nut of the valve bridge adjusting screw and back it off.
Push down on the bridge and turn in the adjusting screw until it touches the valve stem.
Turn in the screw about 10 degrees more and tighten the lock nut.
Check clearance with a feeler gauge between rocker arm and bridge cap.
Loosen the rocker arm adjusting screw lock nut and set the clearance.
Tighten the lock nut of the adjusting screw.
Repeat in firing order 1-5-3-6-2-4, turning the engine 120° between cylinders.

Check the fuel injection start pressure diagnostic

⚠ Do not allow injected fuel to contact skin or body - it has extremely high pressure and can penetrate skin

Tools: Nozzle tester, Wrench

Attach the fuel injection nozzle to the nozzle tester.
While watching the pressure gauge, push the handle down slowly.
The pressure indicated when the gauge needle suddenly decreases is the injection start pressure.
If out of standard, turn the adjusting screw to the standard value.
Tighten the screw to increase pressure and loosen it to decrease pressure.
Secure the cap nut and the set screw to their specified torques.

Change coolant maintenance

⚠ Do not allow hot coolant to contact skin

⚠ Dispose of drained coolant according to local regulation

Start the engine and operate it until coolant temperature is 70°C to 80°C; stop the engine.
Remove the radiator filler cap after the cap is cool enough to remove.
Loosen engine and water pump drain plugs and remove radiator drain plug; drain coolant.
Remove drain plugs of the air cooler pipes and drain.
Flush the cooling system with cleaning solution and clean water.
Fill the radiator with LLC and soft water at the specified concentration.
Operate the engine until coolant temperature is 70°C to 80°C; stop and check level.

Change fuel filter (cartridge type) maintenance

⚠ Do not use the filter wrench to tighten - it may damage the cartridge

Tools: Filter wrench

Clean the area to keep dirt out of the filter base.
Allow the fuel to drain in a container.
Using a filter wrench, remove the used filter.
Clean the gasket of a new filter and coat it with clean diesel fuel.
Clean the filter base and install the new filter by hand.
When the gasket contacts the base, tighten 3/4 to 1 turn more by hand.
Prime the fuel filter.
Start the engine, run at low idle several minutes and check the filter base for leaks.

Change hydraulic governor oil filter maintenance

Place a container under the governor oil filter.
Loosen the air vent plug and remove the case from the bracket; remove the used element.
Remove the oil pipe from the center bolt and remove the center bolt.
Put a new element in the case and install the case to the bracket; tighten the center bolt.
Install the oil pipe to the center bolt and install the drain plug.
Remove the air vent plug and fill up the filter with engine oil; install the air vent plug.

Clean air cleaner element maintenance

⚠ Never service the air cleaner when the engine is running

⚠ Do not clean the element by bumping or tapping

⚠ Wear protective face shield, clothing and shoes

Tools: Pressure air

Direct pressure air inside the element along the length of pleats.
Insert a light inside the clean, dry element and inspect.
Discard the element if rips or tears are found.
If the indicator still shows RED shortly after installation, change the element.

Engine storage preparation maintenance

⚠ It is not necessary to drain the coolant if it contains LLC in 30% to 60% concentration

Drain the oil and fill with rust preservative (JIS K2246 NP-10 or equivalent).
Fill the fuel tank with a mixture of rust preservative (JIS K2246 NP-9) and fuel.
Start and operate the engine at low idle for 5 to 10 minutes (800 to 1000 rpm).
Stop the engine and spray volatile rust preservative in the silencer.
Drain the rust preservative-fuel mixture.
Apply a coat of rust preservative to exposed machined surfaces.
Cover the air inlet and exhaust openings and the breather with taping.
Loosen the fan drive belt.
Tape the starter and alternator terminals and cover with polyethylene sheet with desiccant.
Remove, charge, clean and grease the batteries; store in a dry, cool place.
Cover the engine for weather protection.

Fill the oil pan maintenance

⚠ Hot oil and components can cause personal injury

Tools: Filter wrench

Remove the crankcase filler cap and fill with recommended oil.
Remove the rocker cover and lubricate the valve mechanism and fill the camshaft oil bath.
Check the oil level with a dipstick; keep between MAXIMUM and MINIMUM marks.
Check the oil pan and related parts for oil leaks.
Crank the engine with fuel supply shut off to confirm oil pressure rises.
Start the engine, run about 10 minutes, stop and add oil.

Fill the radiator maintenance

⚠ Crank the engine with the fuel supply shut off

⚠ Check coolant level only after engine has stopped and cap is cool enough to touch

Close engine and water pump drain cocks and tighten the radiator drain plug.
Remove the filler cap and pour pure, undiluted LLC into the radiator.
Add soft water slowly to avoid air pockets; loosen the air vent on top of the thermostat.
Install the filler cap, then crank the engine several times for 10 seconds at about 1-minute intervals.
Check coolant level and add coolant; fill the reserve tank to the FULL mark.
Run under light load until thermostat valve opening temperature is reached to mix LLC with water.
Stop the engine and check the coolant level; add coolant if low.
Check hose joints for coolant leaks.

Prime the fuel system maintenance

⚠ Lock the priming pump cap securely; looseness may cause wear, cap to be shaken off and fuel leakage - a fire hazard

Tools: Wrench

Loosen the air vent plug on the fuel filter about 1.5 turns.
Turn the priming pump cap to the left to unlock and move it up and down.
After fuel showing no visible bubbles comes out, tighten the air vent plug.
Loosen the air vent cap on the fuel injection pump about 1.5 turns.
Move the priming pump cap up and down.
After bubble-free fuel comes out, tighten the air vent plug.
Lock the priming pump cap securely before tightening all air vent plugs.

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

What is the displacement of the Mitsubishi PS6?

The Mitsubishi PS6 has a displacement of 24.5 liters with 6 cylinders.

Which generators use the Mitsubishi PS6 engine?

The Mitsubishi PS6 powers 1 generator set(s), including Mitsubishi S6R S6R2.

What is a common problem with the Mitsubishi PS6 engine?

A commonly reported issue on generators using the Mitsubishi PS6 is: Engine lacks power. Cause: Oil viscosity incorrect. Fix: Change oil..