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If you are unsure if your engine is an N14, be sure to check the data plate. This will have N14 followed by the horsepower and any identifiers, such as 'N14330'.


General Information and Specifications

Listed here are general specifications for the Cummins N14.
• Bore and stoke: 5.5x6 inches.
• Engine weight, automotive / industrial (dry): 2805 lb / 2901 lb.
• Wet engine weight, automotive / industrial: 2925 lb / 3022 lb.
• Minimum oil pressure, idle: 10 psi.
• Minimum oil pressure, at 1200 RPM: 25 psi.
• Oil pan capacity: 8 to 9.5 gallons.
• Oil change capacity: 8.7 to 10 gallons.
• Cooling system capacity: 20-21 quarts.
• Maximum coolant pressure at cylinder block: 24 psi at 1700 RPM, 46 psi at 2300 RPM.
• Maximum top tank temperature: 205 to 220 degrees F.
• Minimum exhaust pipe size: 5 inches.
• Valve protrusion: Minimum of -0.0025 inches to 0.0 inches.
• Cylinder head thickness: Minimum of 4.360 inches, maximum of 4.387 inches.
• Flatness maximum (total overall length): 0.003 inches or 0.08mm.
• Camshaft end clearance: Maximum of 0.013 inches.


Troubleshooting and Recommendations

Listed here are some general recommendations for troubleshooting. As a reminder, be sure to always use an experienced Diesel mechanic if you have to perform any major procedure.

Engine Vibration (general)
If your engine is experiencing excessive vibration, follow these steps as a guide to identify the problem.
• If possible, check the engines software for a high amount of inactive codes first to make sure it is not an electronic problem.
• Check that the battery is fully charged and replace.
• Check the oil level to make sure it is not too high.
• Inspect ground and surrounding areas for signs of fuel leaks.
• Check that the engine idle is not set too high or low.
• Look for frothy oil, or other signs of air being in the oil.
• Ensure the fuel lines allow for fuel to be transferred (no obstructions.)
• Make sure no components are touching the frame, including the exhaust system, clamps, air intake, etc.
• If it is a marine engine, check that the isolators are in good condition and the gear ratio to make sure it is matched correctly.

Engine vibrates when stationary (below 1050 RPM)
This should be followed after checking everything under part one of the vibration troubleshooting.
• Disconnect anything that can cause excessive load, such as PTOs.
• Check the belts by removing them and running the engine. If the vibration stops then purchase new belts and replace.
• Check the front engine mount capscrews. This can be done by loosening only the isolator capscrews for the front engine mount. If the vibration goes away then check the engine mount isolators for damage and that they are properly aligned.

Engine vibrates when engine is not stationary (above 1050 RPM)
This is when your N14 Cummins vibrates when it is moving (or not at idle.) Be sure to check the general section before advancing to this section.
• If the vibration increases as the engine speed increases, then it is probably due to a component that is not balanced.
• Check the engine mount isolators for any damage or wear.
• Remove the belts and run the engine. Replace the belts if vibration goes away.
• Check the vibration damper. If it has any dents, raised surfaces or cracks then replace it. Measure the vibration at eight different spots, four along the inside and four along the outer part. If any part measures more than 0.010 inches thicker than any other part, it must be replaced.
• Check the air compressor timing.
• Isolate any gear driven components to make sure they are not causing any problems.
• Check the flywheel and housing for any signs of warping or damage.

Large amount of white smoke seen
The following are possible causes of white smoke in the Cummins N14 exhaust.
• Check or replace the block heater if it is equipped and not heating the engine.
• Improper type or poor quality fuel.
• Raw fuel in the intake manifold.
• Injectors are damaged.
• Coolant is leaking into the combustion chamber.
• Piston rings need to be replaced.

Large amounts of black smoke seen
The following conditions can cause excessive black smoke to be emitted from the Cummins N14 engine.
• Restrictions, obstructions or damage to the air intake, fuel drain line or exhaust system.
• Fuel pump is broken or not calibrated correctly.
• Wrong fuel type.
• Injectors are not calibrated.
• Turbocharger has a wheel clearance that is not proper.

Smoke seen when trying to start engine
The following can cause the N14 Cummins engine to smoke and either difficult to start or unable to start at all.
• Wrong fuel grade in motor.
• Fuel system has air in it.
• Fuel plugs in cylinder head.
• Damaged o-rings or injectors.
• Valve protrusion is not correct.

Engine overheating
Check the following if your Cummins N14 is overheating.
• Coolant level is correct.
• Damage to the fan or radiator fins.
• Cold weather cover is closed.
• Loose or broken fan drive belt.
• All hoses going to or from the cooling system.
• Problem with intake manifold temperature gauge, coolant temperature gauge or thermostat.
• Combustion gasses, fuel or air in cooling system.
• Radiator core is obstructed or has a malfunctioning j-valve.
• Radiator shutters not opening completely.

Coolant loss or coolant is leaking
When trying to isolate the source of the coolant loss, these areas should also be checked.
• Check the aftercooler and its connections (if equipped).
• Check the radiator cap. For the Cummins N14, the minimum pressure rating for the cap is 7psi.
• Coolant fill lines and cooling hoses.
• Air compressor cylinder head, including its gasket.
• Rocker lever housing.
• Cylinder head and its gaskets.

Alternator suspected to not be charging
The following can cause the Cummins N14 to not charge the battery like it should.
• A loose pulley on either the main shaft or water pump shaft.
• Corroded battery cables.
• The voltage regulator is not working.
• A fuse (or wire) may be blown or loose.
• Battery is too hot.

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