Northern Lights M643K Generator Set

Tools: torque wrench

1. Retighten head bolts after first 50 hours when engine is cold.
2. Loosen nuts and remove rocker arm cover.
3. Tighten bolts with torque wrench in sequence shown.
4. Tighten evenly in 2 or 3 passes, ending at specified torque.

1. Adjust after cylinder head bolts are retightened; engine cold and not running.
2. Turn engine by hand until #1 cylinder inlet valve starts to open and exhaust starts to close.
3. Turn crankshaft one more full turn and adjust both valves for this cylinder.
4. Loosen lock nut and adjust clearance between rocker arm and valve guide.
5. Set clearance to 0.008 in. (0.2 mm) for both intake and exhaust.
6. Repeat for each cylinder individually.
7. Replace rocker arm cover and tighten cover nuts to 7.2 - 8.7 ft/lbs.

⚠ Escaping diesel fuel under pressure can penetrate skin.

Tools: cardboard or wood

1. Loosen bleed screw A on top of filter.
2. Pump hand primer B on fuel lift pump until pure fuel escapes from bleed screw A.
3. Tighten bleed screw A.
4. Loosen bleed screw C and pump until pure fuel escapes.
5. If engine does not start, loosen a fuel line at injector, pump until pure fuel escapes, and tighten.
6. After starting, use cardboard to check for fuel leaks.

⚠ Overtightening can damage filter housing.

Tools: filter wrench

1. Remove old filter with filter wrench and discard.
2. Make sure old gasket is removed and clean mount face.
3. Spread thin film of engine oil on new filter gasket.
4. Screw filter on until gasket meets sealing surface.
5. Tighten one-half turn farther by hand only.
6. Fill engine, start, check for leakage, stop, wait 3 minutes, and check oil level.

⚠ Open sea cock before running engine on marine sets.

1. Flush every 600 hours or every 12 months, whichever comes first.
2. Marine sets: remove expansion tank cap and drain engine block.
3. Open block drain cock and pour clean water into expansion tank until drains run clear.
4. Let water drain completely, close drains, and refill with recommended mixture.
5. Industrial sets: remove radiator cap and open drain cocks on radiator and engine block.
6. Flush until water from radiator and engine drain is clear.
7. Close drain cock and refill with recommended coolant mixture.
8. Clean fins on radiator.

⚠ Never use a flushing oil.

1. Change oil when engine is warm.
2. Loosen clamp on oil change tube, remove cap, and drain oil.
3. Replace cap and tube.
4. Refill engine with recommended oil.
5. Capacity with new oil filter is 3.2 quarts (3.0 liters) for 643K and 673K.

⚠ Place protection under screwdrivers to avoid damaging pump housing.

Tools: needle-nose pliers or two screwdrivers

1. Change seawater pump impeller every 600 hours or as needed.
2. Remove pump end cover.
3. Pry out impeller using needle-nose pliers or two screwdrivers.
4. Remove all pieces of failed impeller.
5. Clean inside of housing.
6. Press in new impeller and place sealing washers in outer end of impeller center.
7. Replace cover using new gasket.

1. Marine sets: drain fresh water and seawater cooling systems; shut off seacocks before opening drain cocks.
2. Drain water supply lines and wet exhaust line.
3. Loosen seawater pump cover and drain pump.
4. Industrial sets: drain and flush radiator and cooling system.
5. Fill fuel tank or add biocide.
6. Seal air cleaner inlet, exhaust opening, crankcase breather pipe, and fuel tank vent.
7. Store set in dry protected place.
8. Change crankcase oil and filter.
9. Loosen alternator belt.
10. Disconnect and clean battery.
11. Clean outside of unit and apply corrosion preventative.

⚠ Use protective clothing and open filler cap carefully when engine is warm.

1. Check water level about 1 in. (2.5 cm) below filler cap sealing surface when cold.
2. Check crankcase oil level with dipstick; oil must be in waffled area.
3. Check fuel tank level and open any fuel valves.
4. Marine sets: close sea-cock, check and clean sea strainer, reopen sea-cock.
5. Marine sets: place battery switch in ON position.

⚠ Battery gas can explode; keep flames and sparks away.

1. Check battery electrolyte level and add distilled water if necessary.
2. Booster and main batteries must have the same voltage rating.
3. Connect positive terminal of booster battery to positive terminal of main battery.
4. Connect negative terminal of booster battery to ground on engine block.
5. Remove booster battery after starting engine.

⚠ Holding preheat ON too long can burn out glow plugs.

⚠ Excessive cranking on marine sets with water lift muffler can cause engine damage.

1. Hold Shutdown Bypass-Preheat switch ON for 10 to 20 seconds before starting a cold engine.
2. While holding preheat ON, push Engine Control switch to START.
3. As soon as engine starts, release both switches.
4. Do not crank starter for more than 20 seconds consecutively.
5. If engine does not start after three 20-second cranks, remove raw water pump impeller.

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