Cummins/Onan 5.5 HGJAE Generator Set

⚠ Voltage/frequency-sensitive equipment may be damaged by power line frequency variations; disconnect them before adjustments.

Tools: Variable load bank up to 7 kW, Frequency meter (within 0.3%), Voltmeter (within 0.5%), AC ammeter

1. Warm up the genset for at least 5 minutes at 1/2 to 3/4 rated load with the choke fully open.
2. Adjust frequency close to the Table 8-3 value with the speed adjusting nut.
3. With the engine warm, remove all loads and adjust the idle stop screw to 51-53 Hz (60 Hz genset) or 41-43 Hz (50 Hz genset).
4. Let the throttle lever go and recheck/adjust No-Load frequency to Table 8-3; bump the governor arm to check stabilization.
5. Connect rated load; if droop is out of spec move the governor spring hook one or two notches and recheck.
6. Confirm the governor does not hunt under the loading sequence.

⚠ Voltage/frequency-sensitive equipment may be damaged; disconnect before adjusting

Tools: load bank, frequency meter, voltmeter

1. Warm up genset five minutes at 1/2 to 3/4 rated load.
2. Adjust frequency to Table 8-4 value with speed adjusting nut.
3. With engine warm and no loads, set idle stop screw to 51-53 Hz (60 Hz).
4. Recheck no-load frequency and bump governor arm for stability.
5. Connect rated load; move governor spring hook to correct droop.
6. Check for hunting under the specified load sequence.

Tools: Socket wrench, Feeler gauge, Torque wrench

1. Adjust when the engine is at room temperature.
2. Remove the spark plugs so the engine is easier to turn over.
3. Use a socket wrench on the generator pulley nut to turn the engine clockwise; remove the snap-in cover.
4. Remove the valve covers with rags in place to catch oil.
5. Turn engine until No. 2 intake valve is at max lift; adjust No. 1 intake valve lash.
6. Turn engine until No. 2 exhaust valve is at max lift; adjust No. 1 exhaust valve lash.
7. Turn engine until No. 1 intake valve is at max lift; adjust No. 2 intake valve lash.
8. Turn engine until No. 1 exhaust valve is at max lift; adjust No. 2 exhaust valve lash.
9. Secure valve covers using new gaskets and torque cover screws to 5.5 lb-ft (8 N-m).
10. Replace the spark plugs and pulley nut cover.

Tools: Battery terminal puller, Torque wrench

1. Loosen the governor shaft nut by turning it clockwise and remove the arm.
2. Use a battery terminal puller to break the taper fit of the shaft in the arm hub.
3. Reattach arm and hub making sure the pins and holes engage; thread the shaft nut on counterclockwise.
4. Check free rotation of the arm and let the governor spring take up all play; linkage must push throttle against the wide open throttle stop.
5. Torque the shaft nut to 8 lb-ft (11 N-m) counterclockwise.
6. Push the governor arm down and check for binding or interference.

Tools: Feeler gauge, Torque wrench

1. Bar the engine until the lands on the flywheel directly face the coils.
2. Place a 0.012 inch (0.03 mm) thick feeler gauge between the coil and the land.
3. Hold the coil tight against the feeler gauge and land and torque the two mounting bolts to 5 lb-ft (7 N-m).

Tools: feeler gauge, torque wrench

1. Bar the engine until the flywheel lands directly face the coils.
2. Place a 0.012 inch (0.3 mm) feeler gauge between coil and land.
3. Hold coil tight against gauge and land.
4. Torque the two mounting bolts to 5 lb-ft (7 N-m).

⚠ Hazardous voltage: touching uninsulated live parts can cause severe injury or death

Tools: AC voltmeter, frequency meter

1. Disconnect all generator loads and connect accurate AC volt and frequency meters.
2. Start genset; let voltage and frequency stabilize 5 to 10 seconds.
3. Rapidly press control switch to START 6 times within 1 minute of start.
4. Adjust up: press START and release quickly (voltage rises about 0.6 volt).
5. Adjust down: press START and release after about 2 seconds (voltage drops about 0.6 volt).

⚠ Gasoline is flammable and explosive

Tools: gallon container, fuel pressure gauge

1. Disconnect the fuel return line between genset and supply tank.
2. Be prepared to collect fuel in a gallon container.
3. Prime the genset for exactly one minute.
4. Verify flow is approximately 1 quart (0.9 liter) per minute and pressure about 45 psi.
5. Reconnect the fuel return line.

Tools: leak down tester, socket wrench

1. Warm engine ten minutes if it will start.
2. Disconnect negative battery cable and remove spark plug.
3. Rotate engine to top dead center on compression stroke.
4. Connect leak down tester to shop air and set calibration.
5. Screw air fitting into spark plug hole and attach tester.
6. Read percent leakdown; listen for leakage points if over 30 percent.

⚠ The high pressure spray from a hydraulic line can penetrate the skin, leading to possible blood poisoning.

Tools: Two wrenches

1. Provide enough slack in connected hoses to prevent strain due to pump movement.
2. Support, restrain and protect hydraulic hose to prevent chaffing.
3. Do not bend hose tighter than the hose manufacturer recommends.
4. Use wide-sweep 90-degree fittings.
5. Always use two wrenches when tightening hydraulic fittings.
6. Install an SAE Class 4 filter (10 micron) in the system.
7. Fill the reservoir and crank the engine with spark plug cables disconnected until oil reaches the pump.
8. Purge air by running the genset a few seconds at a time until metallic noise stops.

1. Repair any damage to and seal all holes in the vapor-tight, fire-resistive barrier between genset and coach interior.
2. Make sure all mounting bolts and brackets are secure.
3. Make sure all battery, AC output, control, exhaust and fuel connections are proper and in good repair.
4. Perform the service checklist before placing the genset in service.

⚠ Running the genset without oil in the hydraulic pump will destroy the pump.

⚠ The high pressure spray from a leak or fitting in a hydraulic line can penetrate the skin, leading to possible blood poisoning.

Tools: Torque wrench

1. Apply molybdenum disulfide paste or equivalent to the shaft spline.
2. Torque the two flange screws to 20 lb-ft (26 N-m).
3. Do not start the genset before the pump is connected and filled with oil.