Cummins/Onan MDGDC Generator Set

1. Push both selector switches (S1, S2) on the controller to their OFF positions.
2. Set the pots initially: Gain 20%, I 20%, D 30%, Droop 0%.
3. If a remote speed pot is used, set it at its midpoint.
4. Start the set and adjust the Speed pot to obtain the required output frequency: 60 Hertz (1800 RPM) or 50 Hertz (1500 RPM).
5. Warm up the set under load until it is up to normal operating temperature.
6. Disconnect the load and turn the GAIN pot to 100 percent or until operation becomes unstable, then turn it counterclockwise until stable.
7. Adjust D as in the GAIN step.
8. Adjust I as in the GAIN step.
9. Readjust Speed if necessary.
10. Push the throttle to minimum speed position and hold until minimum speed; release and observe overshoot (2 to 5 Hertz may be acceptable).
11. If overshoot is unacceptable, turn the I pot clockwise slightly to reduce overshoot.
12. If the set hunts during steady state, turn the I pot counterclockwise slightly until stable.

1. Turn the Start Fuel Limit pot fully clockwise; it requires no further adjustment.
2. Set the pots initially: Gain mid-position, Stability mid-position, Rated Speed fully counterclockwise.
3. If a remote speed pot is used, set to fully counterclockwise position.
4. Start the set and adjust the Rated Speed pot to obtain the required output frequency: 60 Hertz (1800 RPM) or 50 Hertz (1500 RPM).
5. Warm up the set under load until it is up to normal operating temperature.
6. Disconnect the load and turn the Gain pot fully clockwise or until unstable, then turn counterclockwise until stable.
7. Adjust Stability as in the Gain step.
8. Readjust Rated Speed if necessary.
9. Push the throttle to minimum speed and hold until minimum speed; release and observe overshoot (2 to 5 Hertz may be acceptable).
10. If overshoot is unacceptable, turn the Gain pot clockwise slightly to reduce overshoot.
11. If the set oscillates during steady state, turn the Stability pot counterclockwise slightly until stable.

1. Turn the governor idle and speed adjusting screws while the engine runs at normal operating temperature under full load.
2. Adjust droop to within five percent of nominal frequency (3 Hertz for 60 Hertz sets and 2.5 Hertz for 50 Hertz sets).
3. Check operation under various loads and increase droop if the governor hunts.
4. Readjust full-load frequency if droop is adjusted.

⚠ Do not make adjustments in the control panel or on engine with unit running.

1. Adjust the output voltage plus or minus five percent of nominal voltage using the adjustment screw on the back of the power supply outlet box.
2. Call your distributor if the required voltage cannot be obtained by this adjustment.

⚠ Diesel fuel is highly combustible. Do not smoke near fuel tanks and fuel lines.

1. Loosen the fuel line fitting at the filter head.
2. Pump the priming lever on the fuel lift pump until fuel starts flowing from the fitting and is free of air.

⚠ Battery gases are explosive and can cause severe personal injury if ignited.

⚠ Wear protective goggles, rubber gloves and an apron.

1. Add distilled water as necessary and check the specific gravity.
2. Recharge the batteries if the specific gravity is less than 1.260.
3. Clean and tighten the battery terminals and cable connectors and coat with Vaseline to retard corrosion.

Tools: Hose clamp

1. Loosen the hose clamp to remove the smaller filter and the three retaining springs for the larger filter.
2. Cover the inlet openings to prevent the entrance of dirt or debris.
3. Run low pressure water, warm or cold, from inside to outside (opposite the normal airflow direction).
4. Detergent can be used as long as the filter is thoroughly rinsed with clean water.
5. Always allow the air filter to dry before use; do not use compressed air to dry a wet filter.

⚠ Used engine oils have been identified as causing cancer or reproductive toxicity

Tools: Filter wrench

1. Run the engine until it is up to operating temperature and shut it off.
2. Open the oil drain valve and drain the oil into a suitable container.
3. Remove the oil filter with a filter wrench.
4. Fill the new filter with oil and apply a film of oil to the gasket.
5. Screw the filter on by hand until the gasket just touches the filter head; tighten another 3/4 turn.
6. Close the oil drain valve and fill with oil to the high mark (H) on the dipstick.
7. Start the engine and check for leaks.
8. Shut off the engine and wait for 10 minutes; refill to the high mark (H) if necessary.

⚠ To prevent severe scalding, always let the engine cool down before removing the coolant pressure cap.

⚠ The sea water pump has a neoprene impeller that can disintegrate in seconds if pump prime has been lost.

1. If heat exchanger cooled, prime the sea water pump by disconnecting the pump outlet hose and pouring water into the pump outlet, then reconnect the hose and open the sea cock.
2. Fill coolant until the expansion tank is approximately half full; bleed air from any air vents while filling.
3. Run the engine while watching the coolant level in the expansion tank; add coolant so the tank is full at normal operating temperature and secure the pressure cap.