Cummins/Onan G-Drive Generator Set

⚠ Do NOT tighten the inner jam nut excessively; the spring retainer will bend and the control rod will fail.

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

Tools: Socket and breaker bar

1. The fan belt must be installed and under fan idler arm spring tension.
2. Turn the adjusting screw until the end of the slot on the lower control rod end touches the spacer.
3. Note that one of the nuts has left-hand threads.
4. Hold the adjusting screw and tighten the two jam nuts.
5. For control rod with spring, turn the inner jam nut until spring retainer washers touch the cylinder.
6. Hold the inner jam nut and tighten the outer jam nut.

⚠ The adjusting screw must not turn when the lock nut is tightened.

Tools: Torque wrench, Torque wrench adapter ST669

1. Adjust crossheads before adjusting valves, on the cylinder with both valves closed.
2. Loosen the crosshead adjusting screw locknuts on intake and exhaust.
3. Turn the adjusting screw out at least one turn.
4. Hold the crosshead down against its guide.
5. Turn the adjusting screw in until it touches the valve stem top without raising the crosshead.
6. Hold the screw and tighten the locknut to the specified torque.
7. Torque value with adapter ST669: 45 N-m [35 ft-lb].
8. Torque value without adapter: 60 N-m [45 ft-lb].

⚠ Use the correct firing order for the engine being serviced or parts will be damaged.

Tools: Feeler gauge, Torque wrench, Inch pound torque wrench 3376592, Torque wrench adapter ST669

1. Steam clean engine to prevent dirt entering when covers are removed.
2. Remove the rocker lever covers and all related components.
3. Rotate engine clockwise until the damper mark aligns with the pointer.
4. Identify the cylinder with both valves closed and rocker levers loose.
5. Loosen the valve adjusting screw locknut.
6. Insert the correct feeler gauge: intake 0.43 mm, exhaust 0.80 mm.
7. Tighten locknut to 60 N-m [45 ft-lb] without adapter; recheck clearance.
8. Install the rocker lever cover with a new gasket; torque 7 N-m [62 in-lb].

⚠ Cleaning an air filter element with excessive compressed air pressure can damage the filter media.

1. Remove the wing nut securing the bottom cover to the housing.
2. Pull the element down from the center bolt.
3. Pull the cover and element straight out to avoid damage.
4. Remove the gasket from the outlet end of the housing.
5. Inspect the gasket; replace if necessary.
6. Install the new element and assemble the bottom cover.

⚠ Do not remove the radiator cap from a hot engine.

⚠ Do not allow oil to get in the filter; it will adversely affect the DCA.

1. Remove the water filters.
2. Clean the area around the filter head and the gasket surface.
3. Close the valve on the filter head to prevent water loss.
4. Lubricate the seal on the new filter with clean engine oil.
5. Install the new coolant filter until the seal touches the head.
6. Turn the filter an additional 1/2 to 3/4 of a turn after contact.
7. Open the valve on the filter head.

⚠ Do not use caustic cleaners; aluminum components will be damaged.

⚠ Wait until coolant temperature is below 50 C [120 F] before removing the pressure cap.

1. Drain the cooling system; do not allow it to dry out.
2. Add 3.8 liters [1 U.S. gal] Fleetguard RESTORE per 38 to 57 liters [10 to 15 U.S. gal] capacity.
3. Fill the system with plain water.
4. Operate the engine at least 85 C [185 F] for 1 to 1-1/2 hours.
5. Shut off the engine and drain the cooling system.
6. Fill with clean water and run at high idle five minutes above 85 C.
7. Drain again; repeat flushing until drained water is clean.
8. Refill with fully formulated coolant or 50/50 antifreeze mixture.

⚠ The engine does NOT contain oil. Do NOT operate the engine.

1. Operate the engine at high idle until coolant reaches 70 C [160 F]; turn off.
2. Disconnect the fuel lines to the engine fuel filter and the injector return line.
3. Put both fuel lines in a container of diesel fuel.
4. Start the engine; then transfer the supply line to preservative oil.
5. Run until preservative oil flows out of the injector return line; turn engine off.
6. Reconnect the fuel lines, then drain the oil pan sump, oil filters, and fuel filters.
7. Disconnect electrical wiring from the fuel pump solenoid.
8. Crank the engine slowly, spraying lubricating oil into the intake manifold.

⚠ Make sure the fuel filter is installed tightly but not overtightened.

Tools: Filter wrench Part No. 3375049

1. Clean the area around the fuel filter head and filter.
2. Remove the fuel filter with filter wrench, Part No. 3375049.
3. Clean the filter head gasket surface with a lint-free towel.
4. Apply a light film of clean engine oil to the filter gasket surface.
5. Fill the filter with clean fuel and lubricate the o-ring with 15W-40 oil.
6. Install the filter until the gasket contacts the filter head surface.
7. Tighten an additional one-half to three-fourths turn.
8. Vent the fuel system manually.

⚠ Avoid direct contact of hot oil with your skin. Used engine oil can be carcinogenic.

Tools: Oil filter wrench Part No. 3375049

1. Operate the engine until water temperature reaches 60 C [140 F]; shut off.
2. Remove the oil drain plug from the bottom of the oil pan.
3. Remove the oil filters with oil filter wrench Part No. 3375049.
4. Clean the filter head and gasket surfaces.
5. Coat new filter gaskets with clean 15W-40 oil; fill filters with clean oil.
6. Install filters until the gasket contacts the head, then tighten 3/4 turn.
7. Install and torque the oil drain plug to 60 N-m [45 ft-lb].
8. Fill with clean oil and run engine at idle; check for leaks.

⚠ Tilt the housing to prevent the thermostats from falling out.

Tools: Thermostat seal driver ST1225

1. Drain the cooling system.
2. Remove the thermostat housing.
3. Remove the thermostats and seals.
4. Clean all gasket surfaces and bores.
5. Inspect thermostat; discard if barrel is worn or fretted.
6. Install the thermostat by pushing on the outer rim.
7. Install seals with the seal lip positioned up.
8. Fill the cooling system and check for leaks at 70 C [160 F].

⚠ Do not hammer on the fuel pump while removing the coupling; hammering will cause damage and possible engine failure.

Tools: T-bolt puller

1. Install a protective cover over the discharge port and nozzle connector inlet.
2. Clean the debris from around the inline fuel injection pump.
3. Remove the cover.
4. Remove electrical connections and all fuel lines.
5. Remove all of the oil lines.
6. Move the timing lock pin to the locked position if the pump is to be reused.
7. Disconnect the coupling bolts and loosen the four bracket mounting bolts.
8. Remove the injection pump and bracket at an angle as one unit.

⚠ Wear protective clothing and eyewear when steam cleaning to prevent personal injury.

Tools: Injector bore brush, Inverted hold down clamp or puller Part No. 3825142

1. Use an injector bore brush to clean the injector nozzle bore.
2. Check the inside of the nozzle holder sleeve for dirt or debris.
3. Install new o-rings into the injector grooves; lubricate with clean engine oil.
4. Confirm the seal ring is fitted to the tip of the injector.
5. Inspect the bore in the cylinder head for debris.
6. Align the fuel inlet connection hole to the opening in the rocker housing.
7. Install the injector and the connector tube; hand tighten.
8. Install the hold down clamp; torque to 65 N-m [48 ft-lb].