Northern Lights L753 Engine

Tools: Adjustment screw, Lock nut wrench

1. Adjust valve clearance after first 50 hours and every 1000 hours thereafter.
2. Perform after cylinder head bolts have been re-tightened; engine cold and not running.
3. Bring No. 1 cylinder to top dead center on compression stroke by aligning crank pulley top mark with timing gear case mark.
4. Remove rocker arm cover; if No. 1 inlet and exhaust valves do not move, it is at TDC; if they move, turn crankshaft one full turn and realign marks.
5. Loosen lock nut and adjust clearance between rocker arm and valve guide for intake and exhaust valves.
6. Set both intake and exhaust valve clearance to 0.008 in. (0.2 mm).
7. Repeat for each cylinder; adjust each set of valves individually.
8. Replace rocker arm cover; tighten cover nuts to 5 - 8 ft/lbs (0.8 - 2.3 kg/m).

⚠ Do not run engine with air cleaner removed.

1. Inspect air cleaner every 250 hours; check more often in dusty conditions.
2. If dirty, wash element in soapy water, rinse and dry thoroughly.
3. Replace if necessary.
4. Ensure no impurities enter engine while changing element.

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

⚠ Electrolyte is sulfuric acid and can burn or stain.

Tools: Hydrometer

1. Check electrolyte level daily; add distilled water to manufacturer's recommended level.
2. Check and clean batteries, cables, and terminals every 100 hours.
3. Clean corrosion with water and baking soda solution; flush with clean water.
4. Tighten terminals and grease them to inhibit corrosion.
5. Check battery condition with hydrometer every 250 hours.

⚠ Escaping diesel fuel under pressure can penetrate skin; relieve pressure before disconnecting lines.

⚠ Use cardboard or wood, not hands, to search for leaks.

Tools: Hand primer

1. Fuel system is self-bleeding; manual bleeding may be needed after new filter, running out of fuel, or fuel system service.
2. Loosen bleed bolt A on top of filter.
3. Pump hand primer B on fuel lift pump until pure fuel with no bubbles escapes; tighten bleed screw A.
4. Loosen bleed screw C; pump hand primer B until pure fuel escapes; tighten bleed screw C.
5. If engine does not start, loosen one fuel line at an injector while cranking until pure fuel escapes; tighten. Do each line one at a time.
6. After start, use cardboard to check for fuel leaks.

⚠ Overtightening can damage filter housing.

Tools: Filter wrench

1. Change lube oil filter every 250 hours.
2. Use a filter wrench to remove old filter; dispose in approved manner.
3. Remove and discard old gasket; clean mount face.
4. Spread thin film of engine oil on new filter rubber gasket; screw on until gasket meets sealing surface.
5. Tighten one-half turn farther by hand only; do not overtighten.
6. Fill engine with recommended oil; start and check for leakage.
7. Stop engine, wait 3 minutes, and check oil level; add if necessary.

⚠ Close sea-cock before working on cooling system.

⚠ Cooling water is extremely hot; allow engine to cool before working.

1. Flush cooling system every 2500 hours or every 12 months, whichever comes first.
2. Remove expansion tank cap and drain engine block.
3. Open block drain cock; remove plug in lower left side of heat exchanger tank.
4. Pour clean water into expansion tank until water from drains is free of discoloration and sediment.
5. Let water drain completely; close drains and refill with recommended mixture.
6. Check hoses and connections and repair leakage.

⚠ Do not overtighten.

Tools: Filter wrench

1. Primary fuel filter should be installed; Racor fuel filter-water separator recommended.
2. Check primary fuel filter daily; empty collection bowl as necessary.
3. Change primary filter element every 500 hours or as necessary; if bowl fills with water, change primary and secondary elements immediately.
4. Change secondary fuel filter every 500 hours or as necessary.
5. Remove spin-on filter counterclockwise with filter wrench; fill new cartridge with fuel; oil gasket surface.
6. Screw on until gasket contacts sealing surface, then tighten two-thirds turn by hand; do not overtighten.

Tools: Metal rod

1. Clean heat exchanger core once a year or after 2500 hours.
2. Drain expansion tank and heat exchanger.
3. Remove heat exchanger end covers and remove core.
4. Clean inside of core tubes with a metal rod; flush, inspect, and clean again if necessary.
5. Reassemble; fill cooling system, start engine, and check for leaks.

⚠ Never use flushing oil.

⚠ Dispose of waste oil in approved manner.

1. The set is delivered with special break-in oil; change engine oil and filter after 50 hours.
2. Use Service CC 30 weight oil during the first 100 hours.
3. Change oil and filter again at 100 hours using oil in Figure 8; then every 250 hours.
4. During intermittent cold weather, change oil every 100 hours or six weeks, whichever comes first.
5. Change oil at seasonal temperature changes when new viscosity is required; change when engine is warm.
6. Loosen clamp on oil change tube, remove cap, drain oil, replace cap and tube.
7. Refill with recommended oil.

⚠ Place protection under screwdrivers to avoid damaging pump housing.

⚠ Keep extra impeller and cover gasket on board.

Tools: Needle-nose pliers, Screwdrivers

1. Change seawater pump impeller every 1000 hours or as needed.
2. Remove pump end cover.
3. Pry out impeller using needle-nose pliers or two screwdrivers; remove all pieces of failed impeller.
4. Clean inside of housing.
5. Press in new impeller and place sealing washers in outer end of impeller center if not already done.
6. Replace cover using a new gasket.

1. Check tension and wear daily.
2. Press belt with thumb at midpoint between crankshaft and alternator pulleys.
3. Correct tension allows about 3/16 in. (5 mm) deflection.

1. Drain fresh water and seawater cooling systems completely; 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. Fill fuel tank or add biocide per manufacturer's instructions.
5. Seal air cleaner inlet, exhaust opening, crankcase breather pipe, and fuel tank vent with plastic bags and tape.
6. Store set in dry, protected place; cover if stored outside.
7. Change crankcase oil and filter.
8. Loosen alternator belt.
9. Disconnect and clean battery; remove to warm storage if possible.
10. Clean outside of unit; paint scratched or chipped surfaces; apply corrosion preventative to exposed metal.