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MTU QST30G3 Engine

Name: MTU QST30G3 Engine
Brand: MTU

The MTU QST30G3 is a 30 L turbocharged engine rated at 1800 rpm. It powers generator sets from Everdigm, including the EDG-900C. It holds 1007 L (266.0 gal) of oil and 4266 L (1127.0 gal) of coolant.

Also known as: MTU QST30G3

30.0 L

Displacement

1800 rpm

Rated speed

1007.0 L

Oil capacity

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

Engine specifications

Oil capacity	1007.0 L
Coolant capacity	4266.0 L
Displacement	30.0 L
Aspiration	Turbocharged
Rated speed	1800 rpm

Generator sets powered by this engine

Everdigm EDG-900C

How to read your MTU engine serial & model number →

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Fuel rack position range	0 - 21	mm
Clearance	Left/right actuator fault threshold (more than this from commanded position)	1.5	mm
Other	Engine torque adjustment range	0% to +1%	duty cycle units	approximately 0% to +2% engine horsepower
Other	Generator insulation resistance (frame HC6)	5.0 - 1.0	MEG	500 VDC megger setting
Other	Generator insulation resistance (frame P7)	10.0 - 1.0	MEG	500 VDC megger setting
Other	Rack position test voltage (disconnect fuel pump)	1.3 ±.25 to 4.5 ±.25	VDC	racks moved to 0mm
Pressure	Engine oil pressure - idle mode shutdown limit	10	psi	idle mode
Pressure	Engine oil pressure - idle mode warning limit	15	psi	idle mode
Pressure	Engine oil pressure - normal	45-65	psi	QST30 engine
Pressure	Engine oil pressure - run mode shutdown limit	35	psi	run mode
Pressure	Engine oil pressure - run mode warning limit	40	psi	run mode
Resistance	Coolant temperature sender resistance	500 to 2k	ohms
Resistance	Exciter rotor winding resistance (frames 6G, 6H, 6J, 6K)	0.158	ohms	at 68 F (20 C) +10%
Resistance	Exciter rotor winding resistance (frames P7B, P7C)	0.048	ohms	at 68 F (20 C) +10%
Resistance	Exciter stator winding resistance (frames 6G, 6H, 6J, 6K)	17	ohms	at 68 F (20 C) +10%
Resistance	Exciter stator winding resistance (frames P7B, P7C)	17.5	ohms	at 68 F (20 C) +10%
Resistance	Main rotor winding resistance (frame 6G)	1.44	ohms	at 68 F (20 C) +10%
Resistance	Main rotor winding resistance (frame 6H)	1.54	ohms	at 68 F (20 C) +10%
Resistance	Main rotor winding resistance (frame 6J)	1.73	ohms	at 68 F (20 C) +10%
Resistance	Main rotor winding resistance (frame 6K)	1.95	ohms	at 68 F (20 C) +10%
Resistance	Main rotor winding resistance (frame P7B)	1.67	ohms	at 68 F (20 C) +10%
Resistance	Main rotor winding resistance (frame P7C)	1.85	ohms	at 68 F (20 C) +10%
Resistance	PMG winding resistance	2.6 ±10%	ohms
Resistance	PT primary resistance	1K-2.5K	ohms
Resistance	PT secondary resistance	140-225	ohms
Resistance	Thermistor relay trip resistance	3000 ±500	ohms
Speed	Backup start disconnect	850	RPM	sensed PMG voltage greater than 105 volts RMS
Speed	Idle speed	800 ±100	RPM	idle mode
Speed	Overspeed shutdown	115% ±1%	% of nominal
Torque	Bearing cartridge fasteners	4.5	ft-lbs
Torque	Control housing capscrews	20	ft-lbs
Torque	Diode pigtail terminals	24	in-lbs
Torque	Drive disc cap screws	607	ft-lbs
Torque	Engine adaptor endbracket to flywheel housing capscrews	95-105	ft-lbs
Torque	Exciter stator fasteners	4.5	ft-lbs
Torque	Main rotor terminals	23	in-lbs
Torque	Rotating rectifier diodes	36 to 42	in-lbs
Torque	Rotor drive disc to engine flywheel capscrews	150-180	ft-lbs
Torque	Surge suppresser terminals	24	in-lbs
Voltage	Multiplexer control line voltage A32-J3-23	3.0 ±0.25	VDC	measured from digital board connector J3 with A32-J3 disconnected
Voltage	Multiplexer control line voltage A32-J3-24	2.4 ±0.25	VDC	measured from digital board connector J3 with A32-J3 disconnected
Voltage	Multiplexer control line voltage A32-J3-27	1.4 ±0.25	VDC	measured from digital board connector J3 with A32-J3 disconnected
Voltage	PMG voltage (50 Hz sets)	at least 150	VAC	across J10-1 & J10-4, J10-4 & J10-5, J10-5 & J10-1
Voltage	PMG voltage (60 Hz sets)	at least 180	VAC	across J10-1 & J10-4, J10-4 & J10-5, J10-5 & J10-1

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
Grease	Lithium based grease, Mobilux No. 2 or Shell Alvania R3		-30°C to 120°C	81.0 ml	End bearing grease; quantity 2.74 oz (81 ml), divided equally between the bearing, bearing cap cavity and bearing cartridge cavity

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
101	IDLE MODE	Indicates the engine is operating in idle mode. Grounding the engine idle input causes generator build-up to be inhibited and the engine to be governed at 800 RPM.	Warning	When ground is removed from the input, the genset returns to normal speed and voltage.
102	EMERGENCY STOP	Indicates local or remote Emergency Stop.	Shutdown	Pull the button out (or turn clockwise to allow it to pop out). Move the Run/Off/Auto switch to Off. Press the Reset switch. Select Run or Auto, as required.
200	LOW OIL PRESSURE	Indicates engine oil pressure has dropped to an unacceptable level.	Warning	If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow the 201-SHUTDOWN procedure. To check oil pressure, access the Oil Pressure menu prior to clearing the fault.
201	LOW OIL PRESSURE	Indicates engine oil pressure has dropped below the shutdown trip point.	Shutdown	Check oil level, lines and filters. If oil system is OK but oil level is low, replenish. Reset control and restart. Oil pressure limits are listed in Table 4-3.
204	OIL PRES SENDER	Indicates that the control has sensed that the engine oil pressure sender is out of its working range.	Warning	Check that the engine oil pressure sender is properly connected.
210	LOW COOLANT TEMP	Warning occurs when engine coolant temperature is 70 F (21 C) or lower. May be indicated even though coolant heaters are operating when ambient temperature falls below 40 F (4 C).	Warning	Check for coolant heater not connected to power supply (blown fuse or disconnected cord); check for low coolant level and replenish; check for open heater element (check current draw).
211	HIGH COOLANT TEMP	Indicates the engine coolant temperature is getting close to the recommended maximum temperature limit: 215 F (102 C) standby or 207 F (97 C) prime.	Warning	Reduce load if possible by turning off non-critical loads. Check air inlets and outlets and remove any obstructions to airflow.
212	HIGH COOLANT TEMP	Indicates engine has overheated (coolant temperature above the shutdown trip point: 223 F (106 C) standby or 215 F (102 C) prime).	Shutdown	Allow engine to cool completely. Check for obstructions to cooling airflow; check fan belt; check coolant mixture; check blower fan and circulation pumps on remote radiator installations; reset control and restart.
213	COOLANT SENDER	Indicates that the resistance of the coolant temperature sender is out of range.	Warning	Check the resistance of the sender. Resistance should be 500 to 2k ohms.
214	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Warning	Allow engine to cool completely. Check coolant level in both radiator and coolant recovery bottle and replenish if low; look for possible leakage points and repair. Reset control and restart.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point. LOW COOLANT LVL Shutdown will not occur if genset is in Idle mode (low coolant warning only).	Shutdown	Allow engine to cool completely. Check coolant level in radiator and coolant recovery bottle and replenish if low; repair leaks. Reset control and restart.
220	MAG PICKUP	Indicates mag pickup speed indication is not being sensed or does not match generator set output frequency.	Shutdown	Restart and check RPM on the digital display.
221	FAIL TO CRANK	Indicates possible fault with control or starting system. Engine will not crank.	Shutdown	Check fuse F3 on the Engine Interface board. Clean the battery cable terminals and tighten all connections. Recharge or replace the battery.
222	OVERCRANK	Indicates possible fuel system problem. Engine stops cranking.	Shutdown	Check for empty fuel tank, fuel leaks, or plugged fuel lines. Check for dirty fuel filter and replace if necessary. Check for dirty or plugged air filter and replace if necessary. Reset the control and restart.
223	OVERSPEED	Indicates engine has exceeded normal operating speed (115% ±1% of nominal). Engine runs and then shuts down.	Shutdown	Inspect the mechanical fuel linkage and repair or replace. Check the EFC for binding or damage. Replace governor output module (A38) or digital board (A32) as determined by monitoring the duty cycle.
224	FAIL TO SYNCHRONIZE	The generator set has not synchronized to the system bus within the allowable time frame.		Check the governor system stability and adjust governing and synchronizer parameters as required. Check for fuel system problems which can cause engine instability. Synchronizing time can be improved by widening the synchronizing window and reducing the acceptance time delay.
226	FAIL TO CLOSE	Indicates that the paralleling breaker has been given a signal to close, but has not closed properly.		Verify that the charging mechanism of the paralleling breaker is functioning properly. Check the close signal to the breaker. Verify that the auxiliary contact signals from the breaker to the PowerCommand control are operational.
230	LOW DC VOLTAGE	Indicates battery voltage is below 10 VDC.	Warning	Recharge or replace the battery. Check the battery charger fuse. Clean and tighten or replace the battery cable terminals and cables. Check the engine DC alternator; replace if normal charging voltage is not obtained.
231	HIGH DC VOLTAGE	Indicates battery voltage exceeds 32 VDC.	Warning	Check the voltage float level on the battery charger (lower float level). Check the engine DC alternator; replace if normal charging voltage is not obtained.
232	WEAK BATTERY	Indicates battery voltage drops below 60% of nominal for two seconds during starting.	Warning	Discharged or defective battery. See Warning message 230, LOW DC VOLTAGE.
240	LOW FUEL-DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.
241	LOW FUEL	Indicates fuel supply is running low.	Warning	Check fuel supply and replenish as required.
250	EEPROM ERROR	Indicates PCC memory error. Data corruption of critical operating parameters.	Shutdown	Perform the initial start setup procedure. If the set shuts down on the same EEPROM ERROR message, replace the digital board (A32).
251	EEPROM ERROR	Indicates PCC memory error. Data corruption of noncritical operating parameters.	Warning	Perform the adjustment procedures, save the adjustments and reset the control. If the error persists perform the calibration procedures. If the error still persists replace the digital board (A32).
252	EEPROM ERROR	Indicates PCC memory error. Data corruption of noncritical operating parameters.	Warning	Verify the values or choices selected and repeat the save operation. If the error persists replace the digital board (A32).
260	RACK POSITION	Indicates that one or both of the fuel racks is not at the commanded position.		Check fuel pump connections. Check left and right actuator fuses (A38-F1 & F2) on the governor output module.
261	GROUND FAULT	Customer defined input closed to ground. The nature of the fault is an optional customer selection; fault functions can be programmed to initiate a shutdown or a warning.		Isolate the source of the false signal. Disconnect the signal lead near the control and reset the control. Replace A34 or A32 as determined.
262	DAY TANK	Customer defined input closed to ground. The nature of the fault is an optional customer selection; fault functions can be programmed to initiate a shutdown or a warning.		Isolate the source of the false signal. Disconnect the signal lead near the control and reset the control. Replace A34 or A32 as determined.
263	HIGH GEN TEMP	Customer defined input closed to ground. The nature of the fault is an optional customer selection; fault functions can be programmed to initiate a shutdown or a warning.		Isolate the source of the false signal. Disconnect the signal lead near the control and reset the control. Replace A34 or A32 as determined.
270	PHASE ROTATION	The phase relationship between the generator set and the system bus is not matched.	Shutdown	Using a phase rotation checker, verify that the generator set phase rotation matches the phase orientation of the system bus. Verify that control wiring to the bus PT module on the PowerCommand control is properly connected.
272	FIRST START	The PowerCommand control is not receiving a proper signal from the system master first start sensor. The control reverts to a fallback mode in which breaker closure is automatically allowed if bus is de-energized.	Warning	Verify that the Master First Start Sensor is properly functioning (pulsing voltage present on the terminal). Verify the voltage pulse is present at the PowerCommand Control (terminal TB1-50) and repair interconnection wiring.
301	HIGH AC VOLTAGE	Indicates that one or more of the phase voltages has exceeded 130% of nominal, or has exceeded 110% of nominal for 10 seconds.	Shutdown	Determine if the output voltage the control sees is low or high. Isolate to the alternator/control, regulator module (A37)/A31/A32, PT/CT module (A36), customer interface board (A34), analog board (A33) or the generator per Table 4-30.
303	LOW AC VOLTAGE	Indicates that one or more of the phase voltages has dropped below 85% of nominal for 10 seconds.	Shutdown	Check PMG or field wiring, rotating rectifier assembly diodes, the load and connectors. Isolate to A32/A33, A37/A31, or A36/A33/A34 per Table 4-31.
313	UNDER FREQUENCY	Indicates that engine speed has dropped below 90% of nominal for 10 seconds. Five seconds before shutdown, a Load Dump signal is initiated.	Shutdown	Check fuel supply, intake air supply and load. Check Initial Setup (set size). Isolate to governor output module (A38), digital board (A32) or engine interface board (A31) per Table 4-32.
320	OVERCURRENT	Indicates that generator output current has exceeded 110% of rated for 60 seconds.	Warning	Check load and load lead connections.
321	OVERCURRENT	Indicates that generator output current has exceeded 110% of rated, and that a PCC time/current calculation has initiated an overcurrent shutdown.	Shutdown	Check load and load lead connections.
322	SHORT CIRCUIT	Indicates that generator output current has exceeded 175% of rated.	Shutdown	Check load and load lead connections.
330	OVERLOAD	Indicates that three-phase power output exceeds 105% of standby (or 115% of prime) rating. After five seconds the Load Dump output is activated; after 60 seconds the OVERLOAD warning is activated.	Warning	Check load and load lead connections.
335	REVERSE POWER	Indicates that power is flowing into the generator set rather than out from the unit. Can be caused by engine failure, inability to carry load, or control or interconnection problems.	Shutdown	Verify proper CT orientation, wiring and connections; verify proper connection of load sharing lines; verify the generator set is operating at the correct frequency and voltage per Table 4-34.
337	LOSS OF EXCITATION	Indicates that the alternator excitation system is improperly adjusted or has failed. May also be caused by operation of filters and power factor correction capacitors presenting a leading power factor load.	Shutdown	Start the generator set in RUN mode and check/calibrate output voltage. Check load sharing lines for proper interconnections. See Section 6 Servicing the Generator, Exciter Rectifier and Exciter Rotor.
401	INVALID SETUP	Indicates the digital board is not properly calibrated for the generator set model (the model number corresponding to the cut resistor and the initial setup are not compatible). No initial setup data is saved.		Refer to Digital Board (A32) Calibration in Section 5.
402	INVALID CAL	Indicates that the control senses that more than one calibration resistor has been cut. No initial setup data is saved.		Refer to Digital Board (A32) Calibration in Section 5.
blank	LOAD DEMAND	The PowerCommand control has received a signal to shut down from a remote device. This is a normal operation mode typically used in automatic control systems to minimize generator set operation hours and system fuel consumption.		When the load demand signal is removed, the generator set will automatically start, synchronize, and close to the system bus.

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

Procedures

Angular Alignment Procedure adjustment

⚠ Accidental starting of the generator set during this procedure presents the hazard of severe personal injury or death. Disconnect the negative (-) battery cable(s) before beginning.

Tools: Dial indicator

Fasten a dial indicator to the generator shaft or cooling fan with the sensing point on the capscrew head or drive disc flat surface.
Bar the engine over in a clockwise rotation and record the total indicator reading (T.I.R.).
Measure the distance from generator shaft center to the indicator point and from the flex discs to the generator mounting bolt center.
Compare the distances and multiply the ratio times one half the T.I.R. to determine the shim change.
Add or remove shims from under the generator mounting feet as required.

Engine Torque Adjustment adjustment

Select >> from the Main Menu and proceed to the Torque Adjust %DC menu.
Start the generator set and allow it to reach normal operating speed.
Load the generator set to maximum rated kVA at rated voltage.
Adjust the torque limit up or down to achieve the proper generator set frequency under maximum load.

Generator/PCC Control Isolation Procedure diagnostic

⚠ This test involves unregulated excitation of the generator.

⚠ HAZARDOUS VOLTAGE. Touching uninsulated high voltage parts can result in severe personal injury or death.

Tools: Calibrated meter, 12 volt battery with jumpers

Throw the line circuit breaker OFF and shut down the set.
Remove the accessory box housing cover and remove plug P10 from connector J10 of the voltage regulator output module (A37).
Prepare to measure output voltage across the generator terminals while the set is running.
Bring two jumpers from a 12 volt battery to the X (Field +) and XX (Field -) pins of P10 (X = red wire P10-6, XX = brown wire P10-3).
Check polarity; polarity must be correct or this test will be inconclusive.
Start the set and connect the jumper from the battery negative terminal to the XX lead.
If rated output voltage or higher and balanced voltages are obtained, the generator circuitry is probably okay; refer to Section 4 to troubleshoot the PCC control.
If voltages are unbalanced, troubleshoot the main stator first; if uniformly low, troubleshoot the exciter and field circuits first.

Load Sharing Controls Troubleshoot Procedure diagnostic

Tools: True RMS digital meter

Measure bus voltage and frequency and generator set voltage and frequency with a true RMS digital meter; calibrate sensing circuits and match bus conditions.
Check that the load sharing control wiring is properly connected.
Check that each generator set in the system can carry its rated load.
Fine adjust KW BALANCE and KVAR BALANCE settings under the paralleling setup menu.
If sets share load approximately equally but load oscillates between them, reduce the governor gain.
Consult factory for any other load sharing problems.

Rack Position Fault/Test Procedure diagnostic

Tools: Calibrated RMS multimeter (Fluke 87 or 8060A)

Move the Run/Off/Auto switch to the Off position.
At the engine interface board (A31), place a jumper wire from A31-TP1 to A31-TP2.
Select RACK TEST from the Setup Menu to initiate the fuel rack test.
Verify A38 DS1 (RUN) and A38 DS2 (VCC) LEDs are on; if not, remove jumpers, restart set and troubleshoot.
Check whether fuses A38 F1 and F2 are blown; replace blown fuse and restart set.
Move both racks from 0mm to 19mm from the POS MM menu and read DC volts from J11-B and J11-C to J11-A.
Verify these voltages correspond to the display (± .25 VDC).
Check if both left and right voltages are out of tolerance.
Move the racks to 0mm and monitor the position voltage of the incorrect side.
Disconnect the fuel pump connector; check if voltage rises from approximately 1.3 ±.25 VDC to 4.5 ±.25 VDC.

Testing the Float Switch Assembly diagnostic

Tools: Ohmmeter, Feeler gauge

Remove the fuel pump control cover, disconnect the wiring jack and unscrew the assembly from the top of the day tank.
With an ohmmeter test for electrical continuity between each pair of colored leads while holding the assembly vertical.
Lift each float in turn to 1/8 inch (3 mm) below the C-clip stop and test for continuity.
Replace the assembly if any switch is open or any switch does not open.
Use pipe thread sealant when replacing the assembly.

Testing the PMG diagnostic

⚠ HAZARDOUS VOLTAGE. Touching uninsulated high voltage parts inside the control box can result in severe personal injury or death.

Tools: Wheatstone bridge or digital ohmmeter, Voltmeter

Disconnect plug J10 from the voltage regulator output stage module.
Start the engine and let the speed stabilize.
Measure voltage across lead pairs J10-1 & J10-4, J10-4 & J10-5, and J10-5 & J10-1.
Stop the set and measure electrical resistance across the same lead pairs with a Wheatstone bridge or digital ohmmeter.

Convert Day Tank Controller from 240 VAC to 120 VAC installation

Remove the two jumpers between terminals TB1-6 and TB1-7 and connect one between TB1-5 and TB1-6 and the other between TB1-7 and TB1-8.
Move selector switch S103 on the control PCB to the up position for 120V.
If equipped with a transformer, remove the two jumpers between H2 and H3 and connect one between H1 and H3 and the other between H2 and H4.

Current Transformer (CT) Installation installation

⚠ Improper installation of CT's will cause a 335 Reverse Power shutdown error.

Ensure the CT dot faces toward the generator (conventional current flowing into the dot); dot also indicates pin 1.
CT21 - U load leads (A phase); CT22 - V load leads (B phase); CT23 - W load leads (C phase).
Route the appropriate leads through each CT: 6 lead sets use generator output leads; 12 lead sets use load wires.
For 12 lead sets connect CT secondary wire 1 to pin 1 and wire 2/3 to pin 2 (high voltage) or pin 3 (low voltage).
For 6 lead sets connect CT terminal #1 to metering circuitry and terminal #2/3 to ground.

Magnetic Speed Pickup Unit (MPU) Installation installation

⚠ Do not use fan blade to bar over engine. That can damage blades and cause property damage and personal injury.

Bar the engine until a gear tooth on the flywheel lines up in the center of the mounting hole.
Thread the sensor in gently by hand until it just touches the gear tooth.
Back it out one quarter turn and set the locknut.

Insulation Resistance Testing maintenance

Tools: 500 VAC megger

Disconnect plug J10 from the voltage regulator output stage module.
Disconnect the AC control input leads (marked 5, 6, 7 and 8) from the generator output terminals.
If the RTD option is installed, ground all six RTD temperature leads (18 leads total).
Apply test potential between the winding and ground (winding laminations).
Compare readings with Table 6-1; investigate and correct low readings before returning to service.

Emergency Stop Reset operation

Pull the button out or turn the switch clockwise (button with arrow) and allow it to pop out.
Move the Run/Off/Auto switch to Off.
Press the front panel Reset switch.
Select Run or Auto, as required.

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 oil capacity of the MTU QST30G3?

The MTU QST30G3 engine has an oil capacity of 1007.0 liters.

What is the displacement of the MTU QST30G3?

The MTU QST30G3 has a displacement of 30.0 liters.

Which generators use the MTU QST30G3 engine?

The MTU QST30G3 powers 1 generator set(s), including Everdigm EDG-900C.