Cummins/Onan g183g32 Engine

⚠ The fan belt idler is under tension; do not allow hands between idler and belt or fan hub.

Tools: Straightedge at least 48 inches (1219 mm), 8 mm hexagon wrench, 8-point socket and breaker bar or large wrench, Torque wrench

1. Use a long straightedge to align crankshaft pulley to fan drive pulley; fan pulley 0.25 inch toward engine.
2. Mark current and estimated new fan drive pulley location on shaft.
3. Remove two screws from fan pulley bushing; install one screw in threaded hole to separate bushing.
4. Move bushing to the new location mark.
5. Install the two screws into the bushing and tighten alternately to 67 ft-lbs (91 N•m) torque.
6. Recheck alignment and repeat procedure until alignment is achieved.
7. Install the drive belt using an 8-point socket and breaker bar to hold idler against spring tension.

Tools: Straightedge at least 48 inches (1219 mm) long

1. Use a long straightedge to align the crankshaft pulley to the fan drive pulley.
2. Check for no visible gaps between straightedge and pulley surfaces.
3. Mark current and estimated new fan drive pulley location on shaft.
4. Remove three fan pulley bushing screws; install two into threaded holes to separate bushing.
5. Move bushing to the new location mark.
6. Install the 3 screws through bushing into pulley and tighten sequentially to 29 ft-lbs (39 N·m).
7. Recheck alignment and repeat procedure until achieved.
8. Loosen pillow block bearing mounting bolts; add shims between bearing housing and pedestal.
9. Tighten bearing mounting bolts to 85 ft-lbs (116 N·m), then lockcollars to 38 ft-lbs (52 N·m).
10. Rotate fan by hand; ensure minimum 1/8 inch (3 mm) fan blade tip to shroud clearance.
11. Adjust fan shroud using slotted holes if clearance is insufficient.

⚠ The fan belt idler is under tension. Do not allow hands between the idler and the belt or the fan hub.

Tools: Straightedge at least 48 inches (1219 mm) long, 8-point socket and breaker bar

1. Use a long straightedge to align the crankshaft pulley to the fan drive pulley.
2. Fan drive pulley should be 0.25 inch nominal toward engine from straightedge.
3. Mark current and estimated new fan pulley location on shaft.
4. Remove two fan pulley bushing screws; install one into threaded hole to separate bushing.
5. Move bushing to the new location mark.
6. Install the two screws into the bushing and tighten alternately to 67 ft-lbs (91 N·m).
7. Recheck alignment and repeat until achieved.
8. Install drive belt using 8-point socket and breaker bar to relieve idler spring tension.

Tools: Dial indicator holding device, Magnetic base or clamp

1. Perform only when an objectionable vibration is present.
2. Fasten dial indicator holding device to skid base, engine block, or generator shell so the sensor rests on the generator shaft hub.
3. Bar the engine over clockwise through a couple of rotations and record readings in eight equally spaced points around the shaft diameter.
4. To correct out-of-tolerance T.I.R., remove the capscrews connecting drive discs and flywheel; mark drive discs and flywheel.
5. Rotate engine or generator so drive disc holes are repositioned 180 degrees from original location; retorque capscrews.
6. Re-check shaft alignment; if unchanged, rotate discs 30, 60, or 90 degrees from original location.
7. If T.I.R. still does not improve, inspect flywheel pilot and drive disc runouts.

Tools: Calibrated voltmeter

1. Display the Bus Voltage Calibration submenu.
2. With all gensets OFF, attach a calibrated voltmeter to TB1-A (L1) and TB1-B (L2) of the bus PT module.
3. Start another genset, allow it to reach normal speed and voltage, and connect operating genset to the bus.
4. Calibrate the Bus Volts L1 reading so the display matches the calibrated meter.
5. Shut the generator set OFF.
6. Repeat steps 2 through 5 for Bus Volts L2 and L3.
7. Exit menu to save changes.

⚠ Disconnect negative battery cable(s) before beginning; accidental starting presents hazard of severe personal injury or death.

Tools: Dial indicator, Shims

1. Disconnect the negative (–) battery cable(s) before beginning.
2. Fasten a dial indicator to the generator shaft or cooling fan with the sensing point on the capscrew head or flat of the drive disc at bolt circle diameter.
3. Bar the engine over clockwise (viewed from engine flywheel); do not allow it to roll back on compression.
4. Record T.I.R. as the sum of the maximum positive and negative readings over one revolution.
5. To correct, remove or add equal shims under the four generator mounting feet.
6. Approximate shim change: multiply (step 1 to step 2 distance ratio) by one half the T.I.R.

Tools: Calibrated ammeter

1. Display the Current Calibration submenu.
2. With the genset OFF, attach a calibrated ammeter to L1.
3. Start the genset and allow it to reach normal operating speed.
4. Load the genset to maximum rated kVA at rated voltage.
5. Calibrate the L1 current reading so the display agrees with the calibrated ammeter.
6. Repeat steps 2 through 5 for L2 and L3.
7. Exit menu to save changes.

⚠ Contacting high voltage components can cause electrocution; calibration must be performed by technically qualified personnel only.

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

1. Display the Voltage Calibration submenu.
2. With the genset OFF, attach a calibrated voltmeter to the AC output from L1 to L2.
3. Start the genset and allow it to reach normal operating speed.
4. Calibrate voltage reading for L1 so the display agrees with the calibrated voltmeter.
5. Shut the generator set OFF.
6. Repeat steps 2 through 5 for L2 and L3.
7. Exit menu to save changes.

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

Tools: Jumper leads, 12 volt battery, Voltmeter

1. Throw line circuit breaker OFF and shut down the set.
2. Remove electronics box cover; remove connector 10 from regulator output module.
3. Prepare to measure output voltage across generator terminals while set is running.
4. Bring jumpers from a 12 volt battery to X (Field +, red wire 10-6) and XX (Field –, brown wire 10-3) pins of plug P10.
5. Check polarity again; polarity must be correct or test is inconclusive.
6. Start the set and connect the jumper from battery negative terminal to the XX lead.
7. If rated voltage or higher and phases balanced, generator circuitry is probably okay; otherwise troubleshoot.
8. If voltages unbalanced, troubleshoot main stator first; if uniformly low, troubleshoot exciter and field circuits first.

⚠ Hazardous voltage. After DC test voltage applied, reconnect Grounding Cluster to remove static charge after each test.

Tools: Megger

1. Perform the Generator Set Grounding Procedure.
2. Disconnect connector 10 from voltage regulator output stage and AC control leads 5,6,7,8.
3. If RTD option installed, ground all six RTD temperature leads (18 leads total).
4. Main Stator: remove and separate neutral leads from terminal 'N'.
5. Connect megger between one stator phase and ground, grounding other two phases; test.
6. Repeat stator test for the other two phases.
7. Main Rotor: disconnect rotor and voltage suppressor leads from F1+ and F2-.
8. Connect megger between one rotor lead and ground and conduct the test.

⚠ Layers of dust can cause diodes to overheat and fail. Brush dust off regularly.

Tools: Ohmmeter

1. Disconnect the diode pigtails from the terminal posts.
2. Using an ohmmeter, measure resistance between each diode pigtail and the plate on which it is mounted.
3. Reverse meter test probes and repeat; resistance should be high in one direction and low in the other.
4. If resistance is high or low in both directions, replace the diode.

Tools: Wheatstone bridge, Megger

1. Disconnect the six rotor winding leads from the terminal posts on the rectifier assembly.
2. With a Wheatstone bridge, measure resistance across each pair of windings: U-V, V-W, W-U.
3. Replace the whole rotor shaft assembly if resistance of any winding is not as specified in Tables 4-2/4-3.
4. Disconnect all six exciter rotor leads from diode terminals CR1 through CR6 and isolate from ground.
5. Connect the megger between one lead and ground and conduct the test per Table 4-1.