Cummins N14 – Connecting Rod Assemblies – Cleaning
NOTE: The alpha characters or numbers on the connecting rod cap must be the same as the alpha characters or numbers on the rod.
Do not assemble a new cap to a used rod or a used cap to a new rod.
Remove the capscrews and the caps from the rods.
Warning: When using a steam cleaner, wear protective clothing and safety glasses or a face shield. Hot steam
can cause serious personal injury.
Use solvent or steam to clean the rods.
Use a soft bristle brush to clean the oil drilling.
Dry with compressed air.
Cummins N14 – Pistons – Inspection
Visually inspect the piston bowl, the pin bore, and the skirt for cracks or damage.
Use crack detection kit, Part No. 3375432, or equivalent to check for cracks on the top of the piston and in the
piston pin bore.
NOTE: Do not use pistons with dome cracks larger than one-half (1/2) the rim width or with cracks which extend over
the rim toward the ni-resist insert. Do not use pistons with dome cracks in the rim above the pin bore axis. Do not use
pistons with cracks in the piston pin bore. Do not use pistons with scuff marks, visually unacceptable scratches or cracks in the skirt. If pistons are unacceptable for reuse, do not use the mating piston pins. Cummins recommends replacing pistons and pins in sets.
Visually inspect the piston ring lands and ring grooves for wear. A worn groove will have a detectable step at the
back of the groove and a rolled edge at the surface of the piston or the ring groove outside diameter. Pistons ex-
hibiting this wear are not acceptable for reuse.
Refer to the Parts Reuse Guidelines, Bulletin No. 3810303.
Use piston ring groove wear gauges, Part No. 3823870, 3823869, and a 5-6 inch micrometer, to inspect the top
and second grooves (compression rings).
NOTE: The piston must be replaced if measured dimensions are less than those in the table below.
Measure each ring groove (diameter over pins) when the piston temperature is at 21°C [70°F] in two places 90
degrees apart as shown.
Measure the piston pin bore when the piston temperature is at 21°C [70°F] in two places 90 degrees apart.
NOTE: Add 0.013 mm [0.0005-inch] to the bore inside diameter per 5°C [10°F] temperature rise up to 32°C [90°F].
Visually inspect the piston pin for scratches, grooves, or other damage. Do not reuse if visually unacceptable.
Measure the piston pin outside diameter at both ends as shown in two places 90 degrees apart.
NOTE: Discard the piston pin if it is more than 0.03 mm [0.001-inch] out of round. If piston pin measurements exceed
those in the table, do not reuse. If the piston pin is unacceptable for reuse, do not use the matching piston. Cummins recommends replacing pistons and pins in sets.
Cummins N14 – Pistons – Cleaning
Warning: When using a steam cleaner, wear protective clothing and safety glasses or a face shield. Hot steam
can cause serious personal injury.
Caution: Do not use the glass bead blast method to clean the pistons. The piston will be damaged by the
blast material embedded in the aluminum.
Steam clean the carbon from the pistons.
Caution: The cleaning solvent must be approved for aluminum to prevent damage to the pistons.
Use a kerosene emulsion-based solvent that can be heated to 95°C [200°F] and a cleaning tank that will
constantly mix and filter the solvent.
NOTE: Do not use a solvent that has a pH higher than 9.5 or a solvent that contains chlorinated hydrocarbons with
cresols, phenols, or cresylic components.
Put the pistons into the solvent and allow them to soak for a minimum of 30 minutes.
NOTE: Soak the pistons several hours or overnight for best results.
Caution: Do not use a metal brush to clean the pistons. The ring grooves will be damaged.
Use a non-metallic brush to clean the piston ring grooves.
Repeat the soaking and scrubbing process until the piston is cleaned thoroughly, and dry with compressed air.
Cummins N14 – Cylinder Liners – Inspection
Visually inspect for pitting or erosion in the crevice seal groove.
Replace the liner if pitting or erosion is greater than one-half the width of the crevice seal groove.
Visually inspect the outside diameter for excessive corrosion or pitting. Pits must not be more than 1.60 mm
[0.063-inch] deep.
Replace the liner if the pits are too deep or if the corrosion can not be removed with a fine emery cloth.
Liners which have light pitting or erosion can be used again, but they must be installed with the pitting or ero-
sion positioned in line with the crankshaft.
Visually inspect for cracks on the inside and the outside of the liner.
Replace the liner if cracks are found.
Inspect for cracks under the flange.
NOTE: Cracks can also be detected by using either magnetic inspection or the dye method.
Replace the liner if cracks are found in the flange area.
Visually inspect the exterior of the liners. The presence of any coating can indicate an inadequate concentration
level of supplemental coolant additives (SCA). The proper concentration level of SCA will protect against the for-
mation of scale or oil coatings. SCA’s form a very hard film on the coolant side of the liner which resists damage
from the implosion of air bubbles.The microscopic protective coating of ferrous oxide is invisible and will not be
seen by the naked eye.
Inspect the inside diameters for vertical scratches deep enough to be felt with a fingernail.
NOTE: If a fingernail catches in the scratch, the liner must be replaced.
Visually inspect the inside diameter for scuffing or scoring.
Replace the liner(s) if excessive scuffing or scoring is present. Refer to Parts Reuse Guidelines, Bulletin No.
3810303, for further information.
Visually inspect the inside diameter for liner bore polishing.
A moderate polish produces a bright mirror finish in the worn area with traces of the original hone marks or an
indication of an etch pattern.
A heavy polish produces a bright mirror finish in the worn area with no traces of hone marks or an etch pattern.
Replace the liner if:
1. a heavy polish is present over 20 percent of the piston ring travel area.
2. thirty percent (30%) of the piston ring travel area has both moderate and heavy polish, and one-half (15
percent) is heavy polish.
Refer to Parts Reuse Guidelines, Bulletin No. 3810303, for further information.
Use a dial bore gauge to measure the liner inside diameter in four places 90 degrees apart at the top and the
bottom of the piston travel area.
Replace the liner if measured dimensions exceed limits given above in the table.
Measure the liner flange outside diameter.
Measure the lower press fit area.
Cummins N14 – Cylinder Liners – Cleaning
Remove the crevice seal. Remove the two o-rings.
Caution: Do not use a hone, deglazing, or prebrushing to clean the cylinder liners. Abrasives can damage the
finish and the pattern and can contaminate the liner.
Warning: Wear eye protection. Make sure the wire brush is rated for the RPM being used if the brush is motor
driven.
Use a high quality steel wire brush to clean the liner flange seating area.
Use a fine, fibrous abrasive pad such as Scotch-Briteா 7448, Part No. 3823258, or its equivalent to remove the
remaining carbon.
Warning: When using a steam cleaner, wear protective clothing and safety glasses or a face shield. Hot steam
can cause serious personal injury.
Use a non-metallic bristle brush, detergent soap, and warm water to clean the inside diameter.
Use a steam cleaner or a solvent tank to clean the liners.
Dry with compressed air.
Use clean 15W-40 oil to lubricate the inside diameter of the liners.
Allow the oil to soak in the liner for 5 to 10 minutes.
Continue to lubricate the inside of the liners and wipe clean until the paper towel shows no gray or black res-
idue.
NOTE: Use lint-free paper towels to wipe the oil from the inside of the liners.
Cummins N14 – Cam Bore Rear Cup Plug – Installation
Caution: Do not install cup plugs in the block until the cleaning, inspection, and necessary repair procedures
are completed. This will prevent dirt from being trapped in the engine.
Use cup plug sealant, Part No. 3375068, to seal the outside diameter of the cup plugs.
Use cup plug driver, Part No. 3376818, to install the cup plug.
A cup plug driver handle, Part No. 3376795, is required.
Caution: The cup plug must not be installed more than 2.03 mm [0.080-inch] below the surface of the cylinder
block. The cup plug will interfere with the camshaft if installed deeper than the specification. If a service tool
is not available, install the cup plug (1) flush to 2.03 mm [0.080-inch] (2) below the surface of the cylinder block.
Cummins N14 – Straight Thread Plug and Pipe Plug – Installation
Caution: Do not install straight thread plugs or pipe plugs in the block until cleaning, inspection, and nec-
essary repair procedures are completed. This will prevent dirt from being trapped in the engine.
Use pipe sealant, Part No. 3375066, to lubricate the pipe plug threads.
Install new o-rings on the straight thread plugs. The o-ring used by Cummins Engine Company, Inc., is the only one
recommended by Cummins Engine Company. Lubricate the o-ring with clean 15W-40 oil.
Install a 3/4 – 16 straight thread plug in the piston cooling oil passage. Tighten the straight thread plug.
Torque Value: 75 N•m [55 ft-lb]
Install a 3/8-inch pipe plug in the main oil passage. Tighten the pipe plug.
Torque Value: 27 N•m [20 ft-lb]
Install a 3/8-inch pipe plug in the piston cooling oil crossover passage at the front of the cylinder block. Tighten
the pipe plug.
Torque Value: 27 N•m [20 ft-lb]
Install a 3/4 – 16 straight thread plug in the piston cooling oil passage at the rear of the cylinder block. Tighten the
straight thread plug.
Torque Value: 75 N•m [55 ft-lb]
Install a 3/4 – 16 straight thread plug in the piston cooling oil passage. Tighten the straight thread plug.
Torque Value: 75 N•m [55 ft-lb]
Install a 3/8-inch pipe plug in the main oil passage. Tighten the pipe plug.
Torque Value: 27 N•m [20 ft-lb]
NOTE: These pipe plugs must be flush or below flush with the rear face of the cylinder block.
Install the copper washer and the 7/8 – 18 straight threaded plug in the main oil crossover passage in the front of the
cylinder block. Tighten the straight thread plug.
Torque Value: 88 N•m [65 ft-lb]
Install six pipe plugs and one straight thread plug from the main oil passage on the intake side of the cylinder block.
Install the straight threaded plug from the main oil transfer passage on the intake side of the cylinder block.
(1) Torque Value: 55 N•m [40 ft-lb]
(2) Torque Value: 7 N•m [5 ft-lb]
(3) Torque Value: 25 N•m [15 ft-lb]
(4 to 7) Torque Value: 15 N•m [10 ft-lb]
Cummins N14 – Dowel Pin – Installation
NOTE: Do not install the dowel pins in the block until the inspection and any necessary repair procedures are com-
pleted.
Caution: Do not use a hammer. Damage to the dowel pin will result.
Use a plastic mallet. Install the six cylinder head groove pins, two front cover dowel pins, one water pump dowel
pin, six cam follower housing dowel pins, and two fly wheel housing dowel pins.
Cummins N14 – Camshaft Bushings – Installation
Caution: Incorrect installation will block oil flow to the rocker levers and the cam followers resulting in severe
damage to the engine. Refer to the numbers stamped on the bushings to determine the correct cylinder block
cam bore locations in which the bushings are to be installed.
Install the camshaft bushings in the following order: No. 7, No. 6, No. 5, No. 4, No. 3, No. 2, and No. 1.
Bushing (No. 7) – Installation
An alignment pointer, Part No. 3823635, is used to align the cam bearing oil holes with the oil holes in the block.
To use, mount the bearing on the driver. Place the alignment pointer against the machined side of the block at the
cam follower holes with the end of the rod at the top of the bearing. Rotate the cam bearing until the seam of the
bearing is at the end of the rod. Press the cam bearing in as described.
Install the bushing marked No. 7 on the driver with the location notch to the rear of the engine and at the 6:00
o’clock position.
Push the bushing into the bore until the oil holes in the bushing are aligned with the drillings in the bore.
Use a 2.39 mm [0.094-inch] diameter rod or a 3/32-inch hexagon wrench to check the position and the location of
the oil hole in the bushing and the cylinder block.
The rod must pass through the oil holes in the bushing and into the oil supply drillings in the cylinder block.
Bushings (No. 6 through No. 2) – Installation
An alignment pointer, Part No. 3823635, is used to align the cam bearing oil holes with the oil holes in the block.
To use, mount the bearing on the driver. Place the alignment pointer against the machined side of the block at the
cam follower holes with the end of the rod at the top of the bearing. Rotate the cam bearing until the seam of the
bearing is at the end of the rod. Press the cam bearing in as described.
Use bushing driver (1), Part No. 3375861, to install bushings No. 1, No. 2, No. 4, and No. 6.
Use bushing driver (2), Part No. 3376412, to install bushings No. 3 and No. 5.
Install the tool assembly through the camshaft bore until the driver is in the cavity between the bores where the
bushing is to be installed.
Install the bushing guide into the camshaft bore next to the bore where the bushing is to be installed.
An alignment pointer, Part No. 3823635, is used to align the cam bearing oil holes with the oil holes in the block.
To use, mount the bearing on the driver. Place the alignment pointer against the machined side of the block at the
cam follower holes with the end of the rod at the top of the bearing. Rotate the cam bearing until the seam of the
bearing is at the end of the rod. Press the cam bearing in as described.
Use a 2.39 mm [0.094-inch] diameter rod or a 3/32-inch hexagon wrench to check the position and the location of
the oil hole in the bushing and the cylinder block.
The rod must pass through the oil holes in the bushing and into the oil supply drillings in the cylinder block.
Bushing (No. 1) – Installation
NOTE: Camshaft bushing guide, Part No. ST-1228-6, is not used to install the No. 1 bushing.
An alignment pointer, Part No. 3823635, is used to align the cam bearing oil holes with the oil holes in the block.
To use, mount the bearing on the driver. Place the alignment pointer against the machined side of the block at the
cam follower holes with the end of the rod at the top of the bearing. Rotate the cam bearing until the seam of the
bearing is at the end of the rod. Press the cam bearing in as described.
Use a 2.39 mm [0.094-inch] diameter rod or a 3/32-inch hexagon wrench to check the position and the location of
the oil holes in the bushing and the cylinder block.
The rod must pass through the oil holes in the bushing and into the oil supply drillings in the cylinder block.
Measure the inside diameter of the installed camshaft bushings.
NOTE: If any of the bushings is not within specification, the bushing must be replaced.
Cummins N14 – Cylinder Block Counterbore – Inspec- tion and Machining
Due to the complex nature of troubleshooting procedures required for diagnosis and repair of counterbores, this
information has been excluded from this manual. Complete counterbore repair guidelines can be found in the
NH/NT Counterbore Troubleshooting and Repair Manual, Bulletin No. 3810450, and the N14 Troubleshooting
and Repair Manual, Bulletin No. 3810456.
