Cummins/Onan V12 Series Generator Set

⚠ Injectors must always be adjusted before valves.

⚠ Be careful not to bruise injector tip.

Tools: Inch-pound torque wrench (Snap-On Model TQ12B or equivalent), Screwdriver adapter, Feeler gauge, Wire gauge

1. If used, pull compression release lever back and block open.
2. Bar engine in direction of rotation until No. 1 VS mark appears.
3. Adjust injector plunger, then crossheads and valves of first cylinder.
4. Turn crankshaft to next VS mark per firing order; adjust that cylinder.
5. Continue until all injectors and valves are adjusted.
6. Injector plungers adjusted with inch-pound torque wrench to torque setting.
7. Warm engine to 140°F oil temperature and reset injectors to warm setting.
8. Always make final valve adjustment after injectors and with engine at operating temperature.

⚠ Never roll or tighten a belt over the pulley and never pry it on with a tool such as a screwdriver.

⚠ When two or more belts are used, they must be replaced as a set.

⚠ Do not tighten belt beyond figures given to eliminate belt squeak.

1. Shorten distance between pulley centers so belt can be installed without force.
2. Tighten belts so pressure of the index finger will depress belt to specified deflection.
3. All new belts will loosen after running an hour or more and must be retensioned.
4. If belt can be pushed down 1/8 inch more than recommended, retension.
5. To clean a belt, wipe with approved belt lubricant or hydraulic brake fluid.

Tools: Vacuum gauge or water manometer, Mechanical restriction gauge

1. On naturally aspirated engines attach vacuum gauge or water manometer in middle of intake manifold.
2. On turbocharged/supercharged engines attach checking fixture one pipe diameter upstream of supercharger/turbocharger.
3. Idle engine until normal operating temperature is reached.
4. Operate engine at rated speed, full load and take reading.
5. If air restriction exceeds 25 inches of water or 1.8 inches of mercury, clean or replace element, replace damaged piping, remove excessive bends.

⚠ If end clearance exceeds limits, remove turbocharger from engine and replace with new or rebuilt unit.

Tools: Dial indicator, Feeler gauge

1. Remove exhaust and intake piping from turbocharger to expose ends of rotor assembly.
2. Remove one capscrew from front plate and install a long capscrew; attach indicator.
3. Register indicator point on flat of rotor shaft; push shaft side to side and note total reading.
4. Move indicator point to end of shaft and check end-play.
5. Check radial clearance on compressor wheel only.

⚠ Corrosion resistor must never be used as a main coolant supply line.

1. Select location so resistor will be grounded and inlet line less than 18 inches in length.
2. Secure resistor to engine or mounting bracket with capscrews.
3. Attach inlet and outlet lines.
4. If new hoses installed, cut to length from 5/8 inch I.D. heater hose.
5. Open shut-off valves; start engine and check for leaks.
6. After a few minutes check resistor cover temperature; if cold, disconnect outlet line to bleed air.

⚠ Never use soluble oil in cooling system when a corrosion resistor is installed.

1. Close shut-off valves on inlet and drain lines; unscrew drain plug at bottom of housing.
2. Remove cover capscrews and cover.
3. Remove plate securing element(s); lift element(s) from housing and discard; remove plate below element.
4. Lift spring from housing.
5. Polish plates; if less than half of metal plates can be exposed by polishing, install new plates.
6. Replace spring and lower plate.
7. Remove transparent bag from new element(s); install element(s) in housing.
8. Replace upper plate, gasket and cover.
9. Replace drain plug and open shut-off valves in inlet and drain lines.

⚠ Do not remove case.

⚠ Do not attempt to wash and re-use filter bag.

⚠ Make certain cover capscrews are drawn down evenly to assure a good seal between cover and case.

1. Drain full-flow filter by removing drain plugs (all except V8-350 & VT8-430).
2. For V8-350/VT8-430 remove upper socket head pipe plug and attach drain hose.
3. Loosen filter cover capscrews carefully; element spring forces cover up.
4. Drain oil from case and withdraw element.
5. Turn used bag inside out and inspect for bearing metal, grit.
6. Clean all parts except bag, gaskets and O-rings.
7. Install a new filter bag.
8. Insert element, spring end down; position case to cover with new O-ring(s).
9. Tighten capscrews evenly to assure good seal.
10. Add approximately one gallon clean lubricating oil to fill filter case.
11. Check engine oil level and bring to 'H' mark.

⚠ Mechanical tightening will distort or crack filter head.

1. Unscrew combination case and element; discard.
2. Install new O-ring if element has no integral seal.
3. Fill element with fuel.
4. Install new case and element; tighten by hand until seal touches filter head.
5. Tighten an additional one-half turn.

1. Maintain oil level between marks on dipstick gauge.
2. Change oil in governor at each E check.
3. Use the same grade oil as used in the engine.
4. When temperatures are extremely low, dilute lubricating oil with fuel oil to insure free flow.

⚠ Do not attempt to use substitute elements; element threads and filter paper are of special design.

⚠ Make sure oil supply line to filter is connected at opening marked 'IN'. Reversing connections will lead to turbocharger failure.

1. Unscrew element and discard.
2. Clean filter head with solvent not harmful to aluminum.
3. Inspect head for cracks and distorted threads; discard if damaged.
4. Coat gasket atop new element with clean lubricating oil and fill element.
5. Install element to head; tighten until gasket contacts head.
6. Rotate element an additional one-half turn to seal gasket.
7. Reconnect oil supply and discharge lines.

⚠ Never use emery cloth.

Tools: No. 00 sandpaper

1. Clean dirty commutators with No. 00 sandpaper; never with emery cloth.
2. Replace worn brushes.
3. If brushes wear rapidly, check for incorrect brush spring tension or high mica on commutator.
4. Check output and action of an ammeter indicator after brush replacement.
5. Take unit to electric service station for shorts and incorrect polarization.

⚠ Holes in the element of a dry-type air cleaner render cleaner inoperative; do not use damaged cleaner element.

⚠ Do not concentrate air pressure in one spot.

Tools: Compressed air

1. Wipe dirt from cover and upper portion of air cleaner before disassembly.
2. Loosen clamps and remove cover.
3. Unscrew wing bolt holding inner cover and element; remove element carefully.
4. Remove dust cup and clean.
5. Tap side or bottom ring of element with palm or soft hammer.
6. Blow out element from clean air side with compressed air.
7. Wash element with non-sudsing household detergent and warm water (120-140°F); dry with compressed air (40 psi).
8. Remove retainer clamp; separate upper and lower bodies; remove O-ring.
9. Hold element to light and inspect tubes for dust; remove dust with stiff fiber brush.
10. Inspect gaskets and O-rings; discard if worn or mutilated.
11. Inspect element for holes.
12. Position upper body with gasket on lower body; secure with retainer clamp.
13. Install element and inner cover.
14. Be sure gasket washer is under wingnut; install cover and dust cup.