Cummins/Onan B3.9 Generator Set

Tools: Feeler gauge, Engine Barring Tool, Part Number 3824591, Screwdriver or Allen wrench

1. Remove the rocker lever covers.
2. Locate top dead center (TDC) for cylinder number 1.
3. Rotate the engine clockwise until cylinder 4 (4-cylinder) or cylinder 6 (6-cylinder) intake rocker arm starts to open the intake valve.
4. Adjust only the valves indicated, holding the locknut steady with a wrench and turning the screwdriver or Allen wrench.
5. Tighten the locknut and measure the valve lash again.
6. Mark the vibration damper and rotate the crankshaft 360 degrees.
7. Adjust the remaining valves as indicated.
8. Check the rocker lever covers for cracks and install them.

⚠ To avoid engine or timing pin damage, disengage the timing pin after locating top dead center.

Tools: 1/2-inch drive, Engine Barring Tool, Part No. 3824591, Feeler Gauge, 14-mm Wrench, Flat-Blade Screwdriver or 5-mm Allen Wrench, 15 mm wrench

1. Remove the valve cover.
2. Locate top dead center (TDC) for cylinder No. 1 by barring the crankshaft while pressing on the timing pin.
3. When the timing pin engages the hole in the camshaft gear, cylinder No. 1 is at TDC on the compression stroke.
4. Set only valves indicated by the arrows (E = exhaust, I = intake).
5. Holding the locknut steady with the wrench, adjust the valve clearance with the screwdriver or Allen wrench.
6. Tighten the locknut to 24 N*m [18 ft-lb], and measure the valve lash again.
7. Mark the vibration damper, and rotate the crankshaft 360 degrees.
8. Adjust the remaining valves as indicated; tighten locknuts to 24 N*m [18 ft-lb].
9. Install the rocker lever covers and tighten the capscrews to 24 N*m [18 ft-lb].

⚠ Secure safety chains on the test plugs to any convenient capscrew on the radiator assembly; this test must not be performed without securely fastened safety chains.

Tools: Pressure gauge and regulated shop air supply, Spray bottle with soapy water, Stopwatch

1. Remove the inlet and outlet hoses from the cooler.
2. Install a plug or cap over the outlet side of the cooler.
3. Install a pressure gauge and a regulated shop air supply line with a shutoff valve to the inlet side.
4. Apply air pressure until the pressure gauge reads a steady 207 kPa [30 psi].
5. Shut off the airflow and start a stopwatch; record the leakage at 15 seconds.
6. If the pressure drop is 34 kPa [5 psi] or less in 15 seconds, the cooler is operational.
7. If greater, check all connections with soapy water and repair or replace as necessary.

1. Visually inspect the wastegate actuator hose for cracks or holes. Replace if damaged.
2. Visually inspect the wastegate mounting bracket, actuator rod, and lever for damage.
3. A bent bracket, rod, or lever must be replaced. Refer to Procedure 3-05.

Tools: dial indicator, pressure gauge, regulated air pressure source

1. Attach a dial indicator so its shaft is in line with the wastegate actuator rod.
2. Set the indicator to zero, with no air pressure applied to the wastegate capsule.
3. Connect clean regulated air pressure and a pressure gauge to the capsule.
4. Apply 200 kPa [29 psi]. The rod should move approximately 5 mm [0.200 in] without sticking or air leakage.
5. No air should be heard to leak through a functional wastegate capsule.

⚠ Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50 C [122 F].

⚠ Coolant is toxic. Keep away from children and pets.

⚠ Never use water alone for coolant.

Tools: Drain pan with capacity of 19 liters [5 gal]

1. Drain the cooling system by opening the drain valve on the radiator and removing the plug in the bottom of the water inlet.
2. Check for damaged hoses and loose or damaged hose clamps; replace as required.
3. Fill the system with a mixture of sodium carbonate and water (0.5 kg [1.0 lb] sodium carbonate per 23 liters [6.0 gal] of water).
4. Operate the engine for 5 minutes with the coolant reaching above 80 C [176 F].
5. Shut the engine off and drain the cooling system.
6. Fill the cooling system with clean water; operate engine 5 minutes above 80 C [176 F]; drain again until water is clean.
7. Fill with a mixture of 50-percent water and 50-percent ethylene glycol antifreeze.

⚠ Do not remove the pressure cap from a hot engine; wait until coolant temperature is below 50°C [120°F].

⚠ Coolant is toxic; keep away from children and pets and dispose of in accordance with local environmental regulations.

⚠ Never use water alone for coolant.

Tools: Drain pan with a capacity of 19 liters [5 gal]

1. Open the drain valve on the radiator and remove the plug in the bottom of the water inlet.
2. Check for damaged hoses and loose or damaged hose clamps; replace as required.
3. Fill the system with a mixture of sodium carbonate and water and operate the engine 5 minutes above 80°C [176°F].
4. Shut the engine off and drain the cooling system.
5. Fill the cooling system with clean water and operate the engine 5 minutes above 80°C [176°F].
6. Shut the engine off and drain; repeat until the drained water is clean.
7. Fill with a 50-percent water and 50-percent ethylene glycol or propylene glycol antifreeze mixture.
8. Install the pressure cap.
9. Operate the engine until it reaches 80°C [180°F] and check for coolant leaks.

⚠ Avoid direct contact of hot oil with your skin.

Tools: 17 mm wrench, Container able to hold at least 20 liters [15 qt]

1. Operate the engine until the water temperature reaches 60 C [140 F]. Shut the engine off.
2. Remove the oil drain plug and drain the oil into a suitable container.
3. Clean the sealing surface, check the oil drain plug threads, and install the drain plug.
4. Torque drain plug: steel pan 80 N*m [59 ft-lb]; aluminum pan 60 N*m [44 ft-lb].

⚠ Drain the fuel-water separator into a container and dispose of contents in accordance with local environmental regulations.

Tools: Crescent wrench (if lid can not be removed by hand)

1. Lift up on the filter drain lever to drain fuel for approximately 5 seconds.
2. Clean all debris from around the canister lid.
3. Remove the filter lid and filter element.
4. Install the new element in the canister lid and replace the o-ring.
5. Lubricate the o-ring with clean engine oil.
6. Place the lid back in the canister by twisting clockwise and hand-tighten the lid.
7. Open the bleed screw and operate the hand lever until fuel is free of air, then tighten the bleed screw.

⚠ Mechanical overtightening will distort threads, filter element seal, or filter can.

1. Use the filter drain valve to drain fuel out of the filter for approximately 5 seconds.
2. Clean the area around the fuel filter head.
3. Remove the fuel filter.
4. Lubricate the o-ring seal with clean lubricating oil.
5. Install the filter as specified by the filter manufacturer.
6. Open the bleed screw and operate the hand lever until fuel is free of air, then tighten the bleed screw.

Tools: 8 mm wrench

1. Open the vent screw.
2. Operate the priming button on the lift pump until the fuel flowing from the fitting is air free.
3. Tighten the bleed screw to 9 N*m [80 in-lb].

⚠ While testing the injectors, keep hands and body parts away from the injector nozzle.

⚠ Do not bleed the fuel system on a hot engine.

Tools: 17 mm wrench, 19 mm wrench

1. Loosen one or more fittings at the injectors.
2. Crank the engine to allow entrapped air to bleed from the lines.
3. Start the engine and vent one line at a time until the engine runs smoothly.
4. Tighten the line fittings to 30 N*m [22 ft-lb].