Northern Lights OM673 Generator Set

Tools: feeler gauge, wrench

1. Engine cold and not running; turn engine by hand.
2. Turn until #1 inlet starts opening and exhaust starts closing.
3. Turn crankshaft one more full turn; adjust both valves.
4. Loosen lock nut; set clearance with adjustment screw.
5. Set intake and exhaust clearance to 0.008 in. (0.2 mm).
6. Repeat for each cylinder individually.
7. Replace rocker cover; tighten nuts to 7.2 - 8.7 ft/lbs.

⚠ Fuel under pressure can penetrate skin

Tools: cardboard or wood for leak check

1. Loosen bleed screw A on top of filter.
2. Pump hand primer B until pure fuel without bubbles escapes.
3. Tighten bleed screw A.
4. Loosen bleed screw C; pump until pure fuel escapes.
5. If engine does not start, loosen one injector fuel line.
6. Crank until fuel escapes; tighten line; repeat each line.
7. After start, check for fuel leaks.

⚠ Hand tight only; overtightening damages housing

Tools: filter wrench

1. Remove old filter with filter wrench; discard.
2. Remove old gasket; clean mount face.
3. Apply thin film of engine oil to new gasket.
4. Screw filter on until gasket meets sealing surface.
5. Tighten one-half turn by hand; do not overtighten.
6. Start engine, check leaks, stop, wait 3 minutes, check oil.

⚠ Open sea cock before running engine

1. Marine: remove expansion tank cap and drain engine block.
2. Leave drains open; pour clean water into expansion tank.
3. Flush until drain water is free of discoloration and sediment.
4. Drain completely; close drains.
5. Refill with 50% water / 50% ethylene glycol antifreeze.
6. Check hoses and connections; repair leaks.

⚠ Never use flushing oil

1. Run engine until warm; stop engine.
2. Loosen clamp on oil change tube, remove cap, drain oil.
3. Replace cap and tube.
4. Refill with recommended oil.
5. Check oil level after 3 minutes; add if needed.

⚠ Protect pump housing under screwdrivers

Tools: needle-nose pliers, two screwdrivers

1. Remove pump end cover.
2. Pry out impeller with needle-nose pliers or two screwdrivers.
3. Remove all pieces of failed impeller.
4. Clean inside of housing.
5. Press in new impeller; place sealing washers.
6. Replace cover using new gasket or O-ring.

⚠ Shut off seacocks before opening drain cocks if vessel is in water

1. Drain fresh water and seawater cooling systems completely.
2. Drain water supply lines and wet exhaust line.
3. Loosen seawater pump cover and drain pump.
4. Change crankcase oil and filter.
5. Loosen alternator belt.
6. Disconnect and clean battery; remove to warm storage if possible.
7. Clean outside; paint scratches; apply corrosion preventative.
8. Fill fuel tank or add biocide.

⚠ Excessive cranking can fill water-lift muffler and damage engine

1. Hold Shutdown Bypass-Preheat switch ON 10 to 20 seconds for cold engine.
2. While holding preheat, move Engine Control switch to START.
3. Release both switches as soon as engine starts.
4. Do not crank starter more than 20 seconds consecutively.
5. If no start after three 20-second cranks, remove raw water pump impeller.
6. Reinstall impeller after engine starts, then check exhaust water flow.

1. Remove electrical load from generator set.
2. Run engine 3 to 5 minutes for cool down.
3. Move Engine Control switch to STOP momentarily.
4. Marine sets: shut off seacock, fuel valve, and battery switch.

⚠ Do not use hands to check for leaks

Tools: torque wrench, paper or cardboard

1. Install new copper sealing washer in each injector hole.
2. Screw in injector; tighten to 43 - 51 ft/lbs.
3. Install return line with new copper seals; tighten to 22 - 30 ft/lbs.
4. Install delivery lines loose at injectors for bleeding.
5. Crank engine to fill lines; tighten lines at injectors.
6. Start engine; check for leaks with paper or cardboard.

⚠ Use new copper sealing washers

Tools: wrench

1. Clean dirt around injectors and fuel lines.
2. Relieve pressure by loosening delivery line flare nuts.
3. Remove delivery lines as an assembly; cover openings.
4. Remove return line retaining bolts and return line.
5. Unscrew and remove injectors; do not use pry bars.
6. Discard copper sealing washers; cover holes.

Tools: screwdriver

1. Shut down generator; remove four screws and end cover.
2. Locate brush assembly at ten o'clock; remove two screws.
3. Unplug leads from brush assembly.
4. Attach leads to new brush assembly.
5. Install with plastic ears toward front of generator.
6. Connect wire J to terminal J and wire K to terminal K.