Cummins/Onan 15HQ-4R30 Generator Set

⚠ Never change factory settings of the regulator springs or contact fingers.

Tools: dc voltmeter, screwdriver

1. Snap toggle switch to RHEOSTAT ON position.
2. Adjust manual rheostat for 70 volts exciter voltage across dc brushes A1 and A2.
3. Shift brush rig to position giving the highest voltage (neutral).
4. Adjust manual rheostat to obtain rated AC voltage.
5. Snap toggle switch to REGULATOR ON position.
6. Set regulator rheostat at approximately middle of rotation.
7. Set adjustable resistor to obtain rated AC voltage; retighten clip.

⚠ A soap bubble over the regulator outlet will not accurately test for regulator closing.

Tools: manometer

1. Connect a manometer reading up to 14 inches water column to the regulator test hole near the inlet; turn gas on.
2. Turn closing adjusting screw (G) inward just until manometer reading remains constant when outlet is repeatedly covered and uncovered.
3. Close gas supply valve, remove manometer, bleed air from line, install test-hole plug, open valve.
4. Secure hose between regulator nipple and carburetor inlet with clamps.
5. Operate engine to assure quick starting.

⚠ Be sure all load is removed when adjusting the bumper screw.

Tools: tachometer or frequency meter

1. With engine stopped and tension on governor spring, adjust linkage so carburetor stop lever clears stop boss by not less than 1/64 in.
2. Start plant and allow it to reach operating temperature.
3. With no load, adjust speed screw to proper no-load speed.
4. Apply full rated load at 0.8 power factor and recheck speed.
5. If hunting under load, slightly increase distance between governor main shaft and sensitivity screw.
6. If hunting at no load, screw in bumper spring screw until hunt stops.
7. Tighten all lock nuts.

⚠ Keep spark advanced as far as possible without causing a ping.

Tools: series type timing light

1. Crank engine until number 1 piston is coming up on compression stroke.
2. Continue until flywheel mark IGN is centered in inspection hole above starter.
3. Install magneto and adapter to cylinder head with drive shaft properly engaged.
4. Loosen magneto adjusting clamp screw and turn body counterclockwise to close points.
5. Slowly turn magneto clockwise until ignition points just separate; timing is then correct.
6. Advance or retard by turning magneto body slightly clockwise or counterclockwise.

⚠ This is the only adjustment permitted on the regulator plug-in unit.

Tools: screwdriver

1. Remove the louvered cover from the regulator box.
2. Remove the clamping bar from the metal cover of the plug-in unit.
3. Remove the cover held by two screws at the top.
4. Turn the slotted screw at the center until the hunting just stops.

⚠ Tappets set too tight may cause burned or warped valves and camshaft wear.

Tools: three wrenches, hand crank, feeler gauge

1. Remove the valve chamber cover.
2. Adjust with engine hot and each piston at top dead center on compression stroke.
3. Set tappets in firing order sequence 1-3-4-2, turning hand crank 1/2 revolution per piston.
4. Adjust to 0.014 in. clearance for both intake and exhaust valves.
5. Tighten each tappet lock nut securely.
6. After about 10 hours operation, recheck tappets.

Tools: wrenches, clean cloth, wood plug

1. Shut off fuel supply at tank and run unit until it stops.
2. Fill fuel tank nearly full to lessen condensation.
3. Drain oil while warm; replace drain plug and attach warning tag.
4. Drain entire cooling system if no antifreeze/rust inhibitor is present.
5. Pour two tablespoonfuls of rust inhibitor oil (SAE 50) into each cylinder and crank slowly by hand.
6. Clean generator brushes, holders, commutator and collector rings with a clean cloth.
7. Remove, clean and replace air cleaner; coat exposed parts with grease; plug exhaust outlet.
8. Remove batteries or disconnect cables; provide a cover for the unit.

⚠ Always connect the ground cable lastly.

Tools: wrenches

1. Remove protective grease coatings and wipe the unit clean.
2. Inspect unit for damage and service as needed.
3. Remove the plug from the exhaust outlet.
4. Remove, clean and adjust spark plugs; crank engine by hand to distribute oil.
5. Examine all fuel, oil and water lines and connections; service as needed.
6. Refill cooling system; refill crankcase and air cleaner with correct oil.
7. Check for leaks and correct before starting.
8. Connect battery cables, grounding cable last; start in the regular manner.

⚠ Failure to start promptly usually indicates fuel or ignition system trouble.

1. Set ignition toggle switch to ELECT. START position.
2. Press START switch to crank engine; crank in 5-second periods with 5-second intervals.
3. Hold START switch in contact until plant picks up running speed.
4. If restarting while hot, momentarily pull up automatic choke arm while cranking.

⚠ Keep ignition switch at ELECT. START except while starting manually or making tests.

Tools: hand crank

1. Throw ignition switch to HAND START position.
2. Engage hand crank and use a quick upward pull; do not spin the crank.
3. Block or hold up choke arm for preliminary crankings.
4. If gas fuel, press priming button on Ensign regulator for an instant; do not over prime.
5. After plant reaches running speed, throw ignition switch to ELECT. START.

⚠ Pressing STOP has no effect if the ignition switch is at HAND START position.

1. If practicable, disconnect the electrical load.
2. Press and hold the STOP switch firmly until the plant completely stops.
3. Ensure ignition switch is at ELECT. START position.

Tools: screwdriver, puller, press, plug

1. Remove the four screws mounting the water pump assembly to the engine.
2. Remove the screws holding the end plate on the back of the assembly.
3. Use a suitable puller to remove the pulley from the impeller shaft.
4. Remove the lock ring retaining the bearing at the pulley end.
5. Press the impeller shaft out of the body casting from the rear.
6. Tap the shaft seal out from the front of the casting using a plug; tap gently.
7. Reverse steps to assemble; impeller fins must face the water pump seal.