Cummins/Onan 500 DM Generator Set

1. Close main line circuit breaker and apply approximately 1/4 of rated load.
2. Make sure engine speed is constant.
3. Turn GAIN potentiometer clockwise slowly until engine speed is not constant.
4. Turn potentiometer counterclockwise until a constant speed is achieved.
5. Turn counterclockwise an additional 1/2 division.
6. Use SPEED ADJUST potentiometer for fine speed adjustments of less than ±100 RPM.

1. Turn idle speed potentiometer counterclockwise to its stop, then clockwise 10 turns.
2. Turn run speed potentiometer counterclockwise to its stop, then clockwise 10 turns.
3. Turn gain potentiometer fully counterclockwise.
4. Turn droop potentiometer fully counterclockwise for isochronous operation.
5. Turn droop screw to approximately 40 for 3 percent droop.
6. Turn droop screw to approximately 80 for 5 percent droop.

⚠ Filters should be handled with care to prevent damage.

Tools: compressed air

1. Loosen the eight attaching bolts and lift off the air cleaner head.
2. Remove the air filter element from the filter housing.
3. Blow low pressure compressed air (30 psi/207 kPa) through element from the clean side.
4. Hold nozzle at least 1 inch (25 mm) away to avoid damaging the element.

Tools: compressed air

1. Unsnap four latches holding head, lift off head and remove filter element.
2. Remove and discard precleaner cartridge.
3. Blow low pressure compressed air through pleated paper cartridge from the inside.
4. Hold nozzle at least 1 inch (25 mm) away to avoid damaging the element.
5. Replace pleated paper cartridge at every fourth cleaning.

⚠ Do not use antifreeze with an anti-leak formula; the stop leak element can prevent or retard coolant flow through the filter.

1. Close the shutoff valve.
2. Unscrew the coolant filter and discard.
3. Apply a light coat of lubricating oil to the gasket surface.
4. Install new filter and tighten by hand until seal just touches filter head.
5. Tighten an additional one-half to three-fourths turn.
6. Open the shutoff valve.

⚠ Failure to remove AC power presents a shock hazard and can cause serious personal injury or death.

⚠ Contact with hot coolant can result in severe burns.

1. Remove AC power from coolant heater.
2. Allow heater to cool before proceeding.
3. Remove the head and valve assembly.
4. Clean any scale deposits out of the tank.
5. Remove heating element and scrape off any accumulated scale.
6. Restore AC power to heater after system has been filled with coolant.

⚠ Excessive air pressure while starting the water flow could split the radiator core. Apply air pressure gradually.

Tools: flushing gun, compressed air

1. Open upper and lower radiator hose connections and install the radiator cap.
2. Attach flushing gun nozzle to lower radiator hose connection and fill radiator with water.
3. Gradually apply air pressure to avoid damaging the core.
4. Shut off air and allow radiator to refill; repeat until water runs clean.
5. Remove thermostat to flush block; attach flushing gun to upper radiator hose.
6. Restrict lower hose opening until block fills; apply air pressure and force water out.
7. Replace thermostat and all hoses and refill cooling system.

Tools: compressed air

1. Remove wing nut, flat washer and rubber washer; lift cover away from filter assembly.
2. Lift out breather element, vapor element and gasket.
3. Clean all parts with approved solvent; dry with compressed air (30 psi maximum OSHA).
4. Inspect all parts, replace if necessary.
5. Reassemble filter assembly, replace cover and secure.

⚠ Crankcase pressure can blow out hot oil and cause serious burns. Do NOT check oil while the generator set is operating.

Tools: drain pan, torque wrench

1. Bring engine up to operating temperature and then shut it off.
2. Remove oil drain plug or open drain valve and collect oil in a pan.
3. Replace drain plug or close drain valve; torque to 60-70 ft.lb (81-95 N·m).
4. Fill crankcase to full mark on dipstick; allow for oil filters when drained.
5. Start engine and check for oil leaks.
6. Shut off engine, wait 15 minutes, check oil level, add oil if required.

⚠ Do not permit any flame, cigarette, or other ignition source near the fuel system.

1. Remove both spin-off type fuel filters and discard.
2. Fill new filters with diesel fuel and coat sealing gasket lightly with fuel.
3. Install and tighten by hand until gasket just touches the filter head.
4. Tighten an additional one-half to three-fourths of a turn.

⚠ Always allow 15 minutes after engine shutdown before checking oil level.

1. Unscrew and discard filters (DFW, DFY; DFZ see Figure 6).
2. Fill filters with lubricating oil and lightly coat gasket sealing surface.
3. Position filter on adapter and hand tighten until seal contacts filter head.
4. Advance one-half to three-quarters turn; do not overtighten.
5. Fill crankcase to H mark, run engine to verify no leaks, add oil as necessary.

1. Move Run-Stop-Remote switch on the DC panel to the RUN position.
2. Starter begins cranking; engine should start after a few seconds.
3. Starter disconnects when engine reaches 450 to 570 r/min.
4. If engine does not start, control indicates an overcrank fault after up to 75 seconds.
5. To clear overcrank fault, place switch in STOP and momentarily depress Reset.
6. Wait two minutes for starter motor to cool, then repeat starting procedure.