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MTU 12V/16V 4000 Gx3 Engine

The MTU 12V/16V 4000 Gx3 is a exhaust turbocharging (etc) and charge air cooling (cac) engine. It powers generator sets from MTU, including the 12 V 4000 G23, 12 V 4000 G63, 12 V 4000 Gx3 and 12V4000 G23.

Also known as: MTU 12V/16V 4000 Gx3

Part of the MTU 12V engine family — 3 variants share parts & fitment.

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

Engine specifications

Aspiration	Exhaust turbocharging (ETC) and charge air cooling (CAC)

Generator sets powered by this engine

MTU 12 V 4000 G23 MTU 12 V 4000 G63 MTU 12 V 4000 Gx3 MTU 12V4000 G23

How to read your MTU engine serial & model number →

Common problems

LO P-Fuel (Common Rail pressure < reference value; DBR fuel limitation, start of injection readjusted towards late; suction restrictor of HP fuel block jamming or HP fuel control block wiring faulty. 083
Fix: Contact Service.
HI P-Fuel (Common Rail pressure > reference value; DBR fuel limitation, start of injection readjusted towards late; suction restrictor of HP fuel block jamming or HP fuel control block wiring faulty. 082
Fix: Contact Service.
HI P-Diff. Lube Oil 025
Fix: Replace oil filter.
Wiring TO 3 SD alarm configuration; short circuit or wire break on transistor output 3 (TO 3) 373 AL
Wiring TO 2 SD alarm configuration; short circuit or wire break on recirculation transistor output 2 (TO 2). 372 AL
Fix: 1. Check turbocharger valve/cabling, repair as necessary. 2. Replace ECU.
Wiring TO 1 SD alarm configuration; short circuit or wire break on turbocharger transistor output 1 (TO 1). 371 AL
Fix: 1. Check turbocharger valve/cabling, repair as necessary. 2. Replace ECU.
Violation of second limit for external temperature channel 2 point, which is read via CAN bus 072
Violation of second limit for external temperature channel 1 point, which is read via CAN bus 070
Violation of second limit for external pressure channel 2 point, which is read via CAN bus 076
Violation of second limit for external pressure channel 1 point, which is read via CAN bus 074
Violation of first limit for external temperature channel 2 | (Depending on the corresponding measuring point, which is read via CAN bus) 071
Violation of first limit for external temperature channel 1 point, which is read via CAN bus 069
Violation of first limit for external pressure channel 2 point, which is read via CAN bus 075
Violation of first limit for external pressure channel 1 point, which is read via CAN bus 073
Stop Power Stage SD alarm configuration; internal electronic fault (electronics possibly faulty: start ITS). If the ITS diagnosis result is “electronics OK 363 AL
Fix: 1. Check cabling. 2. Attempt to restart engine.

Compiled from service & troubleshooting documentation across every generator set that uses the MTU 12V/16V 4000 Gx3.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	MTU 12V4000 Gx3 - 04		12V4000Gx3-04	500 hr	Amazon eBay
Fuel filter	MTU 12V4000 Gx3 - 03		12V4000Gx3-03	500 hr	Amazon eBay
Oil filter	MTU 12V4000 Gx3 - 02		12V4000Gx3-02	500 hr	Amazon eBay
Battery	MTU 12V4000 Gx3 - 07		12V4000Gx3-07	500 hr	Amazon eBay
Belt	MTU 12V4000 Gx3 - 06		12V4000Gx3-06	500 hr	Amazon eBay
Coolant	MTU 12V4000 Gx3 - 05	6.0 L	12V4000Gx3-05	500 hr	Amazon eBay
Coolant filter			—
Oil	S4 ACEA C3 or equivalent	6.0 L	12V4000Gx3-01	500 hr	Amazon eBay
Spark plug	MTU 12V4000 Gx3 - 08		12V4000Gx3-08	500 hr	Amazon eBay

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
Engine coolant	Change		12 mo	If engine is out of service for more than one year, change engine coolant and charge-air coolant
Valve gear	Lubricate		6 mo	Lubricate valve gear every 6 months (out-of-service >3 months procedure)

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	Centrifugal oil filter maximum layer thickness of oil residues	45	mm	if exceeded, shorten maintenance interval
Clearance	Valve clearance adjustment trigger deviation	0.1	mm	if deviation from reference value exceeds this
Clearance	Valve clearance deviation from reference value (adjustment threshold)	0.1	mm
Other	Cold start capability air temperature (w/o start aid, w/o preheating, case A)	10	°C
Other	Compressed-air tank condensate drain pressure drop	must not exceed 1	bar
Other	Coolant preheating temperature (min.)	32	°C
Other	Engine coolant pump relief bore - permissible coolant discharge	up to 10	drops per hour
Other	Engine coolant pump relief bore - permissible oil discharge	up to 5	drops/hour
Other	Permissible coolant discharge (coolant pump relief bore)	up to 10	drops/hour
Other	Permissible oil discharge (coolant pump relief bore)	up to 5	drops/hour
Pressure	Final compression pressure	24 to 28	bar	at 120 rpm
Pressure	Fuel prefilter differential pressure (flush filter element threshold)	0.3	bar	engine running at full load or rated power
Pressure	Fuel prefilter differential pressure flush limit	≥ 0.3	bar	engine at full load / rated power
Pressure	Fuel pressure at engine supply connection, max. (starting)	1.5	bar	when engine is starting
Pressure	Fuel pressure at engine supply connection, min. (starting)	-0.1	bar	when engine is starting
Pressure	Lube oil operating pressure before engine (12V 4000 Gx3, continuous 3B)	5.0 to 6.0	bar
Pressure	Lube oil operating pressure before engine (16V 4000 Gx3, standby 3D)	4.2 to 6.5	bar
Pressure	Lube oil operating pressure before engine, from/to	5.0 to 7.0	bar	12V engines
Speed	Firing speed	80 to 120	rpm
Speed	Firing speed, from/to	80 to 120	rpm
Temperature	Coolant preheating, preheating temperature (min.)	32	°C
Temperature	Coolant temperature after engine, alarm	102	°C
Temperature	Coolant temperature after engine, shutdown	104	°C
Temperature	Coolant temperature at engine connection (outlet to cooling equipment)	100	°C
Torque	Battery-charging generator drive belt screw (2)	60 to 65	Nm
Torque	Battery-charging generator drive belt tension screw (1)	42	Nm
Torque	Belt drive screw (1)	42	Nm
Torque	Belt drive screw (2)	60 to 65	Nm
Torque	Centrifugal oil filter clamp	8 to 10	Nm
Torque	Centrifugal oil filter cover nut	5 to 7	Nm
Torque	Centrifugal oil filter rotor cover nut	35 to 45	Nm
Torque	Crankcase breather cover screws	10 ±2	Nm	oil separator / diaphragm cover
Torque	Crankcase breather oil separator cover screws	10 Nm -2	Nm
Torque	Cylinder head cover screws	42	Nm
Torque	Engine oil drain plugs (2) and (3)	100 Nm +10	Nm
Torque	HP fuel line - injector side	20 Nm +5	Nm
Torque	HP fuel line - rail side	30 Nm +5	Nm
Torque	HP fuel line, injector side	30 ±5	Nm
Torque	HP fuel line, rail side	30 ±5	Nm
Torque	Injector adapter	100 ±10	Nm
Torque	Injector adapter (pretighten)	5 to 10	Nm
Torque	Injector hold-down clamp screw (pretighten)	5 to 10	Nm
Torque	Injector hold-down screw and adapter	100 Nm +10	Nm
Torque	Oil drain plugs (2) and (3)	100 ±10	Nm	equipment carrier
Torque	Valve clearance locknut	90 +9	Nm	holding adjusting screw firm
Torque	Valve clearance locknut	90 ±9	Nm	holding adjusting screw firm
Valve clearance	Exhaust valve clearance (short rocker arm)	0.5	mm	cold engine
Valve clearance	Exhaust valves (short rocker arm)	0.5	mm	cold engine
Valve clearance	Inlet valve clearance (long rocker arm)	0.2	mm	cold engine
Valve clearance	Inlet valves (long rocker arm)	0.2	mm	cold engine

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	Capacity	Notes
Coolant		MTU Fluids and Lubricants Specification A001061	160.0 liters	Engine coolant capacity, engine side (without cooling equipment): 12V = 160 liters, 16V = 260 liters. Coolant antifreeze content max. 50%.
Engine oil		MTU Fluids and Lubricants Specification A001061	260.0 liters	12V engines: total engine oil capacity at initial filling 260 liters (standard oil system); 16V engines: 300 liters
Fuel	Diesel fuel			Only fuels of the specified quality required to achieve emission limits must be used
Grease	Kluthe Hakuform 30-10 / Emulgier			Grease for injector O-rings; part X00029933
Other	Cleaner Hakutex 60			Cleaner for centrifugal oil filter rotor parts
Other	Isopropyl alcohol			Cleaning agent for connectors / contacts; part 461 81
Other	Optimoly Paste White T			Assembly paste for injector sealing ring / nozzle retaining nut; part 40477

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

Fault codes

Code	Name	Meaning	Severity	Action
003	HI T-Fuel	Preliminary warning: fuel temperature too high.	Warning	Contact Service.
004	SS T-Fuel	Main warning: fuel temperature too high; engine stop.	Shutdown	Contact Service.
005	HI T-Charge Air	Preliminary warning: charge-air temperature too high.	Warning	Reduce power. Check intercooler.
006	SS T-Charge Air	Main warning: charge-air temperature too high; engine stop.	Shutdown	Reduce power. Check intercooler.
009	AL L1 T-Coolant Intercooler	Preliminary warning: coolant temperature in intercooler too low.	Warning	Reduce power.
010	AL L2 T-Coolant Intercooler	Main warning: charge-air coolant temperature too high; engine stop.	Shutdown	Reduce power.
015	LO P-Lube Oil	Preliminary warning: lube oil pressure too low.	Warning	Check oil level, top up as necessary (Page 146).
016	SS P-Lube Oil	Main warning: lube oil pressure too low; engine will be shut down.	Shutdown	Check oil level; attempt to restart engine (Page 57).
019	HI T-Exhaust A	Preliminary warning: exhaust gas temperature (A-side) too high.	Warning	Check cabling (Page 171); Contact Service.
020	SS T-Exhaust A	Main warning: exhaust gas temperature (A-side) too high. Engine stop.	Shutdown	Check cabling; Contact Service.
021	HI T-Exhaust B	Preliminary warning: exhaust gas temperature (B-side) too high.	Warning	Check cabling; Contact Service.
022	SS T-Exhaust B	Main warning: exhaust gas temperature (B-side) too high. Engine stop.	Shutdown	Check cabling; Contact Service.
023	LO Coolant Level	Coolant level too low	Warning	Check coolant level in expansion tank (Page 153).
024	SS Coolant Level	Coolant level too low	Shutdown	Check coolant level in expansion tank (Page 153).
025	HI P-Diff. Lube Oil	Preliminary warning: oil filter differential pressure too high.	Warning	Replace oil filter (Page 150).
026	HI P-Diff. Lube Oil	Preliminary warning: Oil filter differential pressure too high	Warning	Replace oil filter
027	HI Leak Fuel Level	Preliminary warning: leak-off fuel level too high.	Warning	Check fuel system; Contact Service.
029	HI ETC 2 idle speed	Idle speed of ETC 2 too high	Warning	Contact Service
030	SS Engine Speed	Engine overspeed; reduced fuel injection	Shutdown	Acknowledge alarm; attempt to restart engine.
031	HI ETC 1 overspeed	Preliminary warning: speed of primary turbocharger too high	Warning	Contact Service
032	SS ETC 1 overspeed	Speed of primary turbocharger too high	Shutdown	1. Automatic power reduction by engine control system. 2. Check air filters.
036	HI ETC 2 overspeed	Preliminary warning: speed of secondary turbocharger too high	Warning	1. Reduce power. 2. Contact Service.
037	SS ETC 2 overspeed	Main warning: speed of secondary turbocharger too high; Fuel limitation to a fixed value	Shutdown	1. Reduce power. 2. Contact Service.
038	AL ETC Synchro Fault	Synchronization error between ETCs 1 and 2	Warning	1. Reduce power. 2. Contact Service.
039	AL ETC 2 cut-in failure	ETC2 failed to cut in	Warning	1. Reduce power. 2. Contact Service.
044	L1 Coolant Level Intercooler	Intercooler coolant level too low.	Warning	Check coolant level (Page 161).
051	HI T-Lube Oil	Preliminary warning: lube oil temperature too high.	Warning	Reduce power.
052	SS T-Lube Oil	Main warning: lube oil temperature too high; engine stop.	Shutdown	Reduce power; check engine oil level (Page 146).
057	LO P-Coolant	Preliminary warning: coolant pressure too low.	Warning	Check coolant circuit.
058	SS P-Coolant	Main warning: coolant pressure too low; engine stop or reduced injection quantity.	Shutdown	Automatic engine shutdown; check coolant level.
063	HI P-Crankcase	Preliminary warning: crankcase pressure too high.	Warning	Reduce power; replace oil separator element (Page 114).
064	SS P-Crankcase	Main warning: crankcase pressure too high; engine stop.	Shutdown	Replace oil separator element; Contact Service.
065	LO P-Fuel	Preliminary warning: fuel supply pressure too low.	Warning	Check fuel lines for leaks; clean/flush fuel prefilter; replace filter element; replace fuel filter.
066	SS P-Fuel	Main warning: fuel supply pressure too low; engine stop.	Shutdown	Check fuel lines; clean/flush/replace fuel prefilter element; replace fuel filter.
067	HI T-Coolant	Preliminary warning: coolant temperature too high.	Warning	Reduce power.
068	SS T-Coolant	Main warning: coolant temperature too high; engine stop.	Shutdown	Allow engine to cool down; check coolant cooler; restart engine; Contact Service.
081	AL Rail Leakage	Pressure gradient in rail too low during starting or too high during stopping; HP system leaky, air in system	Warning	Contact Service
082	HI P-Fuel (Common Rail)	Rail pressure > reference value; DBR fuel limitation, start of injection readjusted towards late	Warning	Contact Service
083	LO P-Fuel (Common Rail)	Rail pressure < reference value; DBR fuel limitation; suction restrictor faulty or leakage in HP fuel system	Warning	Contact Service
085	HI T-Recirculation	Preliminary warning: Recirculation temperature too high	Warning	Reduce power.
086	HI T-Recirculation	Main warning: Recirculation temperature too high	Warning	Reduce power.
089	AL Stalling Engine	Engine speed too low	Warning	Check for additional messages.
090	SS No Idling Speed	Idling speed was not attained	Shutdown	Contact Service.
091	SS No Runup Speed	Runup speed was not attained	Shutdown	Contact Service.
092	SS No Starter Speed	Starter speed was not attained; termination of starting sequence; starter rotates too slowly or not at all.	Shutdown	Contact Service.
093	SS T-Preheat	Main warning: preheating temperature too low; coolant temperature too low for engine start; engine start interlock active.	Shutdown	Check preheater.
094	LO T-Preheat	Preheating temperature too low; coolant temperature too low for engine start	Warning	Check preheater.
095	AL Prelubrication Fault	Oil priming failure	Warning	Check oil priming system.
102	AL Consumption Meter Faulty	Consumption meter faulty	Warning	Contact Service
104	AL Eng Hours Counter Defect	Hourmeter faulty	Warning	Contact Service
118	LO ECU Supply Voltage	Preliminary warning: supply voltage too low.	Warning	Check ECU supply voltage; Contact Service.
119	LOLO ECU Supply Voltage	Main warning: supply voltage too low.	Shutdown	Check ECU supply voltage; Contact Service.
120	HI ECU Supply Voltage	Preliminary warning: supply voltage too high.	Warning	Check ECU supply voltage; Contact Service.
121	HIHI ECU Supply Voltage	Main warning: supply voltage too high.	Shutdown	Check ECU supply voltage; Contact Service.
122	HI T-ECU	Preliminary warning: temperature in ECU too high.	Warning	Reduce power; improve engine room ventilation.
134	15V POS ECU DEFECT	Internal voltage (-15 VDC) faulty; automatic engine shutdown	Shutdown	Replace ECU.
136	15V NEG ECU DEFECT	Internal voltage (-15 VDC) missing; automatic engine shutdown	Shutdown	Contact Service.
139	L1 TE BUFFER TEST	Supply voltage of temperature sensors faulty	Warning	1. Check sensors. 2. Replace ECU. 3. Contact Service.
140	TE BUF. ECU DEFECT	Supply voltage of temperature sensors faulty	Shutdown	1. Check sensors. 2. Replace ECU. 3. Contact Service.
142	BANK1 ECU DEFECT	Power output stage for control of the solenoid valves on bank 1 is faulty; Engine does not start	Shutdown	Replace ECU.
144	BANK2 ECU DEFECT	Power output stage for control of the solenoid valves on bank 2 is faulty; Engine does not start	Shutdown	Replace ECU.
145	15V_GOOD ECU DEFECT	Power supply faulty; automatic engine shutdown	Shutdown	Replace ECU.
146	L1 AD-TEST1 SUPPLY	Supply voltage A/D converter too low	Warning	Replace ECU.
147	AD-TEST1 ECU DEFECT	Electronic fault; automatic engine shutdown	Shutdown	Replace ECU.
148	L1 AD-TEST2 SUPPLY	Supply voltage A/D converter too low	Warning	Replace ECU.
149	AD-TEST2 ECU DEFECT	Internal electronic fault; automatic engine shutdown	Shutdown	Replace ECU.
150	L1 AD-TEST3 SUPPLY	Internal electronic fault; automatic engine shutdown	Warning	Replace ECU.
151	AD-TEST3 ECU DEFECT	Internal electronic fault; automatic engine shutdown	Shutdown	Replace ECU.
173	MODULE WRITE LIMIT REACHED	EEPROM write limit reached.	Info	Contact Service.
176	AL LifeData Not Avail	No (appropriate) LifeData backup system available, ECU reset after expiration of time-out period	Warning	Contact Service.
177	AL LifeData restore incomplete	CRC faulty during a data upload to ADEC	Warning	Contact Service.
180	AL CAN1 Node Lost	Connection to one node on CAN bus 1 failed.	Warning	Contact Service.
181	AL CAN2 Node Lost	Connection to one node on CAN bus 2 failed.	Warning	Contact Service.
182	AL CAN Wrong Parameters	Incorrect parameter values entered in data record	Warning	Contact Service.
183	AL CAN No PU-Data	CAN mode selected requiring communication with PU data module; required PU data module not available or not valid	Warning	Contact Service.
184	AL CAN PU-Data Flash Error	Programming error when copying a received PU data module into the Flash module	Warning	Contact Service.
186	CAN1 BUS OFF	Severe fault on Default CAN bus; automatic change-over to Redundant CAN bus.	Warning	Contact Service.
187	AL CAN1 Error Passive	CAN controller 1 has signalled a warning	Warning	1. Inspect CAN bus for short circuit and rectify. 2. Check shielding. 3. Contact Service.
188	AL CAN2 Bus Off	CAN controller 2 is in Bus-Off status; automatic changeover to CAN 1; short circuit, massive interference or Baud rate incompatibility	Warning	1. Inspect CAN bus for short circuit and rectify. 2. Check shielding. 3. Contact Service.
189	AL CAN2 Error Passive	CAN controller 2 has signalled a warning	Warning	1. Inspect CAN bus for short circuit and rectify. 2. Check shielding. 3. Contact Service.

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

Procedures

Valve clearance - Check and adjustment adjustment

Tools: Feeler gauge Y20010128, Torque wrench 60-320 Nm F30047446, Ring socket, 24 mm F30039526

Remove cylinder head cover
Install barring tool
Rotate crankshaft until marking OT-A1 and pointer are aligned
Check TDC position of piston in cylinder A1
Check valve clearance with cold engine: inlet 0.2 mm, exhaust 0.5 mm
Check all valve clearances at two crankshaft positions
Use feeler gauge to determine distance between valve bridge and rocker arm
If deviation exceeds 0.1 mm, adjust valve clearance
Release locknut and set adjusting screw with Allen key
Tighten locknut to 90 +9 Nm holding adjusting screw firm

Cylinder liner - Endoscopic examination diagnostic

Tools: Rigid endoscope Y20097353

Remove cylinder-head cover
Remove injector
Turn crankshaft until crankpin of cylinder to be tested has reached BDC
Insert endoscope into cylinder liner through injector seat
Compile endoscopy report using the table
Depending on findings: no action, further examination, or contact Service (liner replacement)
Install injector
Install cylinder-head cover

Air filter - Removal and installation maintenance

Loosen clamp.
Remove air filter and clamp from flange of intake housing.
Verify that there are no objects in the flange of the intake housing and clean it.
Place new air filter with clamp onto intake housing.
Tighten clamp.
Reset signal ring of service indicator.

Air filter removal and installation maintenance

Loosen clamp
Remove air filter and clamp from flange of intake housing
Verify no objects in flange and clean it
Place new air filter with clamp onto intake housing
Tighten clamp
Reset signal ring of service indicator

Battery-charging generator drive - Drive belt replacement maintenance

⚠ Spring/circlip/tensioning roller preload. Risk of injury!

Remove guard cover
Slacken screws (1) and (2) by half a turn
Place socket adapter or box wrench on screw (3) and press belt tensioner as far as it will go
Tighten screw (2), remove used drive belt and fit new drive belt
Slacken screw (2) by half a turn so tensioner tensions the belt
Tighten screw (1) to 42 Nm and screw (2) to 60-65 Nm
Install guard cover
Readjust belt tension after 30 minutes and after 8 hours engine runtime

Centrifugal oil filter - Cleaning and filter-sleeve replacement maintenance

⚠ Hot oil. Oil can contain combustion residues which are harmful to health.

⚠ Compressed air. Risk of injury!

Tools: Torque wrench 6-50 Nm F30027336

Remove clamp, release Tommy nut and take off cover
Lift rotor, allow oil to drain and remove from housing
Release rotor cover nut and take off rotor cover
Remove filter sleeve and measure thickness of oil residues
If maximum layer thickness exceeds 45 mm, shorten maintenance interval
Disassemble rotor tube, conical disk and rotor base, wash with cleaner and blow out with compressed air
Check sealing ring, fit new one if necessary
Insert new filter sleeve with smooth paper surface facing the wall
Mount rotor cover with sealing ring and tighten rotor cover nut to 35-45 Nm
Fit cover, tighten Tommy nut by hand, fit clamp and tighten 8-10 Nm, tighten cover nut 5-7 Nm

Crankcase breather - Oil separator replacement, diaphragm check and replacement maintenance

⚠ Hot oil. Oil can contain combustion residues which are harmful to health.

Tools: Torque wrench 6-50 Nm F30027336

Remove cover with O-ring
Remove filter element from housing
Insert new filter element in housing
Fit cover with new O-ring
Tighten screws of cover to 10 Nm -2 Nm
Checking diaphragm: remove cover, take off spring, seal and diaphragm
Check diaphragm for damage, fit new if damaged
Mount diaphragm on housing
Install new seal and spring with cover and tighten screws to 10 Nm -2 Nm

ECU - Checking plug-in connections maintenance

Verify that all plug-in connections are securely seated
Secure loose connectors and latch

Engine - Barring manually maintenance

⚠ Unguarded rotating and moving engine components. Risk of serious injury - danger to life!

Tools: Barring tool F6555766, Ratchet F30006212

Remove guard plate
Engage barring tool with ring gear and mount on flywheel housing
Set ratchet onto barring tool
Rotate crankshaft in engine direction of rotation
No abnormal resistance apart from normal compression resistance
For removal follow reverse sequence

Engine - Barring with starting system maintenance

⚠ Unguarded rotating and moving engine components. Risk of serious injury - danger to life!

Release latch of connector X4
Disconnect connector from ECU
Bar engine in unloaded condition: press START button
Let crankshaft rotate until oil pressure is indicated
If starting period expires, re-start after approx. 20 seconds
Connect connector X4 to ECU and latch in position

Engine coolant - Filling maintenance

⚠ Coolant is hot and under pressure. Risk of injury and scalding!

⚠ Cold coolant in hot engine can cause thermal stress.

Turn breather valve of filler neck counterclockwise to first stop and allow pressure to escape
Continue to turn breather valve counterclockwise and remove
Filling with pump: connect pump with hose to drain valve, open it and pump coolant in at 0.5 bar minimum
Fill expansion tank until overflow edge is reached
Close drain valve and fit breather valve
Start engine, run unloaded 10 seconds, stop engine
Check coolant level and top up if required
Alternatively fill coolant through filler neck until level at top edge of filler neck remains constant

Engine oil - Change maintenance

⚠ Hot oil. Oil can contain combustion residues which are harmful to health.

Tools: Torque wrench F30027337, Ratchet adapter F30027341

Provide container to collect oil
Remove drain plug(s) and drain oil
Install drain plug(s) with new sealing ring
Extract all oil from oil pan using hand pump (if used)
Remove drain plug and drain approx. 7 liters from oil heat exchanger and oil filter
Remove drain plugs (2) and (3): approx. 12 liters and approx. 5 liters
Replace engine oil filter
Tighten drain plugs (2) and (3) to 100 Nm +10 Nm
Fill with new oil at filler neck up to max. mark
Bar engine with starting system after oil change and filter replacement

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

Parts cataloged across the MTU 12V family

Part #	Description	Category
W1005	Air filter	Air filter
12V4000Gx3-07	Battery	Battery
12V4000Gx3-06	Belt	Belt
W1241	Drive belts	Belt drive
W1009	Centrifugal oil filter (if fitted)	Centrifugal oil filter
W1011	Combustion chambers	Combustion chambers
W2000	Before starting maintenance work, drain the coolant and flush the cooling systems.	Component maintenance
W2001	Inspect rocker arms and valve bridge for wear. Insert an endoscope through the pushrod bore to visually inspect swing followers and camshaft running surfaces.	Component maintenance
W2002	Clean air ducting.	Component maintenance
W2003	Clean intercoolers and inspect for leakage.	Component maintenance
W2004	Fit new high-pressure sensor in fuel system.	Component maintenance
W2006	Check charge air coolant thermostat and replace thermal actuator (→Workshop Manual)	Component maintenance
W2007	Check centrifugal oil filter for wear (if fitted) (→Workshop Manual)	Component maintenance
W2009	Inspect centrifugal oil filter for wear (if fitted).	Component maintenance
W2010	Overhaul starter.	Component maintenance
W2011	Inspect vibration damper.	Component maintenance
W2062	Crankcase breather: Replace oil separator (→Workshop Manual)	Component maintenance
W2070	Overhaul charge air coolant pump.	Component maintenance
W2110	Overhaul engine coolant pump	Component maintenance
W1063	Overhaul cylinder heads. Visually inspect piston crowns and wear pattern on cylinder liner running surfaces.	Conrod bearing
W1046	Crankcase breathers	Crankcase breathers
W3000	Completely disassemble the engine. Inspect engine components as per Maintenance Manual instructions and repair or fit new components as required.	Extended component maintenance
W3001	Exchange all elastomeric parts and seals for new ones.	Extended component maintenance
W3002	Fit new piston rings.	Extended component maintenance
W3003	Fit new conrod bearings.	Extended component maintenance
W3004	Fit new crankshaft bearings.	Extended component maintenance
W3005	Fit new cylinder liners.	Extended component maintenance
W3006	Fit new antifriction bearings for auxiliary PTOs.	Extended component maintenance
W3007	Fit new high-pressure fuel pump.	Extended component maintenance
W3010	Overhaul battery-charging generator.	Extended component maintenance
07500211a	Screw, Adapter (3)	Fastener
08300126a	Easy-change filter	Filter
12V4000Gx3-02	Engine oil filter	Filter
12V4000Gx3-03	Fuel filter	Filter
12V4000Gx3-04	Air filter	Filter
12V4000Gx3-01	Engine oil	Fluid
12V4000Gx3-05	Coolant	Fluid
W1001	Fuel filter or new fuel filter insert	Fuel filter
W1006	Fuel injectors	Fuel injectors
08300029b	Gasket	Gasket
04000115a	O-ring	O ring
W1008	Engine oil filter	Oil filter
00000705a	Coolant system	Service part / kit
08000139a	Vent plug	Service part / kit
F30006212	Ratchet	Service part / kit
F30047446	Torque wrench, 60-320 Nm	Service part / kit
F30510423	Torque wrench, 10-60 Nm	Service part / kit
F6555766	Barring tool	Service part / kit
1250007	Rubber sleeve	Rubber sleeve
W1250	Rubber sleeves	Rubber sleeves
01200211a	Sealing ring	Seal
075001552	Sealing ring	Seal
07500158a	Sealing ring	Seal
07500159	Sealing ring	Seal
01200209a	Adjustable pointer	Sensor
12V4000Gx3-08	Spark plug	Spark plug
5605892099/00	MTU test kit	Special tools
F30025896	Socket wrench, 17 mm	Special tools
F30025897	Socket wrench, 19 mm	Special tools
F30027336	Torque wrench 6-50 Nm	Special tools
F30027341	Ratchet adapter	Special tools
F30039526	Ring socket, 24 mm	Special tools
F6789889	Installation/removal tool for injector	Special tools
W1041	Turbochargers	Turbochargers

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Common questions

Which generators use the MTU 12V/16V 4000 Gx3 engine?

The MTU 12V/16V 4000 Gx3 powers 4 generator set(s), including MTU 12 V 4000 G23, MTU 12 V 4000 G63, MTU 12 V 4000 Gx3, MTU 12V4000 G23.

How often should you change the oil in the MTU 12V/16V 4000 Gx3?

The MTU 12V/16V 4000 Gx3 oil change interval is every 500 hours.

What is a common problem with the MTU 12V/16V 4000 Gx3 engine?

A commonly reported issue on generators using the MTU 12V/16V 4000 Gx3 is: LO P-Fuel (Common Rail pressure < reference value; DBR fuel limitation, start of injection readjusted towards late; suction restrictor of HP fuel block jamming or HP fuel control block wiring faulty.. Fix: Contact Service..