Northern Lights NL673 Generator Set

Tools: thumb

1. Check tension and wear daily.
2. Press thumb at midpoint between fan pulley and alternator pulley.
3. Correct tension: belt depresses about 3/16 in. (5 mm).
4. Loosen alternator tensioning arm bolt and mounting bolt.
5. Pivot alternator toward engine left or right as required.
6. Tighten mounting bolt and adjusting bolt.
7. Recheck tension after tightening.
8. Recheck after running five minutes at low idle.

1. Press on the belt at the midpoint between fan pulley and alternator pulley with your thumb.
2. Tension is correct if the belt can be depressed about 3/16 in. (5 mm).
3. Loosen the alternator tensioning arm bolt and the alternator mounting bolt.
4. Pivot the alternator at the mounting bolt toward the engine left or right side as required.
5. Tighten the mounting bolt and the adjusting bolt.
6. Recheck belt tension after tightening and again after running 5 minutes at low idle.

Tools: adjustment screw, wrench

1. Adjust every 1000 hours or as needed.
2. Do after cylinder head bolts re-tightened; engine cold and not running.
3. Turn engine by hand until inlet opens and exhaust closes.
4. Turn crankshaft one more full turn.
5. Loosen lock nut and adjust clearance between rocker arm and valve guide.
6. Clearance both intake and exhaust: 0.008 in. (0.2 mm).
7. Repeat for each cylinder individually.
8. Replace rocker arm cover; tighten cover nuts to 5 - 8 ft/lbs (0.8 - 2.3 kg/m).

⚠ Valve adjustments should be done after the cylinder head bolts have been re-tightened.

1. Adjust valve clearance every 1000 hours, or as needed; engine cold and NOT running.
2. Turn the engine over by hand until the inlet valve starts to open and exhaust starts to close (valves rocking).
3. Turn the crankshaft one more full turn and adjust the clearance on both valves for this cylinder.
4. Loosen the lock nut and adjust clearance with the adjustment screw.
5. Clearance on both intake and exhaust valves is 0.008 in. (0.2 mm).
6. Repeat for each cylinder; each set of valves must be adjusted individually.
7. Replace the rocker arm cover; tighten cover nuts to 5 - 8 ft/lbs (0.8 - 2.3 kg/m).

⚠ Escaping diesel fuel under pressure can penetrate skin causing serious personal injury.

Tools: cardboard

1. System is self-bleeding but needs manual bleeding after filter change, running out of fuel, or component removal.
2. Loosen bleed screw A on top of filter.
3. Pump hand primer B until pure fuel escapes from screw A, then tighten A.
4. Loosen bleed screw C; pump hand primer B until pure fuel escapes.
5. If engine does not start, loosen a fuel line at injector.
6. Crank engine until pure fuel escapes; tighten connection.
7. Do each line one at a time.
8. After starting, check for leaks using cardboard.

⚠ Escaping diesel fuel under pressure can penetrate skin causing serious personal injury; relieve all pressure before disconnecting lines.

⚠ Never use hands to search for suspected leaks.

Tools: Cardboard or wood for leak checking

1. Loosen bleed screw A on top of the filter.
2. Pump hand primer B on the fuel lift pump until pure fuel (no bubbles) escapes; tighten bleed screw A.
3. Loosen bleed screw C; pump hand primer B until pure fuel escapes.
4. If engine will not start, loosen a fuel line at the injector, crank until pure fuel escapes, then tighten.
5. After the engine has started, check for fuel leaks using a piece of cardboard.

1. Operate the engine under various conditions, particularly heavy loads with minimal idling.
2. Constantly check engine temperature and oil pressure.
3. Change engine oil and filter at 50 hours.
4. Change oil and filter again at 100 hours.

⚠ Overtightening can damage filter housing.

Tools: filter wrench

1. Change lube oil filter every 250 hours.
2. Use filter wrench to remove old filter.
3. Ensure old gasket removed and clean mount face.
4. Apply thin film of engine oil to new filter gasket.
5. Screw on until gasket meets sealing surface.
6. Tighten one-half turn farther by hand only.
7. Fill engine with recommended oil.
8. Start engine, check for leakage, stop, wait 3 minutes, check oil level.

⚠ Overtightening can do damage to filter housing.

Tools: Filter wrench

1. Use a filter wrench to remove the old filter and dispose of it in an approved manner.
2. Make sure the old gasket is removed and discarded; clean the mount face.
3. Spread a thin film of engine oil on the new filter's rubber gasket.
4. Screw the filter onto the nipple until the gasket meets the sealing surface.
5. Tighten one-half turn farther by hand only; do not use a wrench.
6. Fill engine with recommended oil, start engine and check for leakage.
7. Stop engine, wait 3 minutes, and check oil level; add oil if necessary.

⚠ Cooling water reaches extremely high temperatures.

⚠ Allow engine to cool before working on cooling system.

1. Flush every 2500 hours or every 12 months, whichever comes first.
2. Remove radiator cap and open drain cocks on radiator and engine block.
3. Pour clean water into radiator until water from radiator is clear.
4. Close radiator drain and continue flushing until water from engine drain is clear.
5. Open all drain cocks and drain completely.
6. Close drain cock and refill with recommended coolant mixture.
7. Use 50% water / 50% ethylene glycol antifreeze mix.
8. Check hoses and connections and repair any leakage.

⚠ Allow the engine to cool before working on the cooling system; open the filler cap carefully using protective clothing.

1. Flush the cooling system every 2500 hours or every 12 months, whichever comes first.
2. Remove radiator cap and open drain cocks on radiator and engine block.
3. Pour clean water into radiator until water coming from radiator is clear of discoloration.
4. Close the radiator drain and continue flushing until water from the engine drain is clear.
5. Open all drain cocks and drain completely.
6. Close drain cock and refill with 50% water / 50% ethylene glycol antifreeze mixture.
7. Check hoses and connections and repair any leakage.

⚠ Never use a flushing oil.

⚠ Dispose of waste oil in an approved manner.

1. Change oil and filter after 50 hours.
2. Use Service CC 30 weight oil during first 100 hours.
3. Change oil and filter again at 100 hours.
4. After this, change every 250 hours.
5. In cold weather, change every 100 hours or six weeks.
6. Change oil when engine is warm.
7. Drain via oil change tube; replace cap and tube.
8. Refill; capacity with new oil filter is 3.3 quarts (3.1 liters).