Cummins ISX11.9 CM2250 – Service Manual 001-005   Bearings, Connecting Rod

The connecting rod for the ISX11.9 CM2250 uses a fractured split connection between the rod cap and the rod. Connecting rods with a fracture split surface must be treated with caution. The two pieces of the connecting rod can not be rubbed together. This will damage the mating surfaces. Use care to not drop either piece of the connecting rod. Fracture split connecting rods must only be handled if the two pieces of the connecting rod are tightened to the correct specification, or completely separated.

WARNING  To reduce the possibility of personal injury, avoid direct contact of hot oil with your skin.

WARNING  Some state and federal agencies have determined that used engine oil can be carcinogenic and cause reproductive toxicity. Avoid inhalation of vapors, ingestion, and prolonged contact with used engine oil. If not reused, dispose of in accordance with local environmental regulations.

CAUTION  Rotating the engine with the connecting rod caps loose or removed can cause damage to the piston cooling nozzles. Always remove the piston cooling nozzles prior to removing the connecting rod and piston assembly.

• Drain the lubricating oil. Refer to Procedure 007-037 in Section 7.
• Remove the lubricating oil pan. Refer to Procedure 007-025 in Section 7.
• Remove the oil transfer connection. Refer to Procedure 007-061 in Section 7.
• Remove the lubricating oil suction tube. Refer to Procedure 007-035 in Section 7.
• Remove the block stiffener plate. Refer to Procedure 001-089 in Section 1.
• Remove the piston cooling nozzles. Refer to Procedure 001-046 in Section 1.

Rotate the crankshaft so that two of the connecting rods are at bottom dead center.

CAUTION  Do not damage the fractured split surface on the connecting rod or connecting rod cap while the connecting rod caps are removed. If the fractured split surface is damaged, the connecting rod and connecting rod cap must be replaced to reduce the possibility of engine damage. Incorrect assembly can damage the rod.

CAUTION  Make sure the piston cooling nozzles have been removed before removing the connecting rod cap. Damage to the nozzles can occur if they are not removed.

Do not remove the capscrews at this time.

Loosen the connecting rod capscrews.

Hit the connecting rod capscrews with a rubber hammer to loosen the rod caps.

Remove the capscrews and the rod cap. Note the corresponding rod and rod cap as well as the orientation of the rod cap.

Be careful not to damage the fractured split connection.

DO NOT set the rod cap down on its fractured split face.

NOTE: Both the rod cap and the connecting rod are serialized on one face to make sure of proper orientation.

NOTE: Minimize the number of joint interactions between the connecting rod and rod cap. There is only a finite number of times a connecting rod and rod cap can be assembled and removed before the joint loses its proper interaction.

Remove the bearing shell from the rod cap and mark the cylinder number and the letter “L” on the flat surface of the bearing tangs.

Install two of the capscrews back into the rod finger tight.

Use a T-handle piston pusher to push the rod up far enough to allow the upper bearing shell to be removed.

Do NOT push against the fractured split face of the rod.

Use caution to avoid scratching or other damage to the journal with the rod, capscrew or piston pusher

Remove the bearing shell and mark the cylinder number and the letter “U” on the flat surface of the bearing tangs.

WARNING  When using a steam cleaner, wear safety glasses or a face shield, as well as protective clothing. Hot steam can cause serious personal injury.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

Steam clean the parts and dry with compressed air.

Inspect the rod caps, connecting rod bearing saddles, and capscrews for nicks, cracks, burrs, scratches, and fretting.

Inspect the fracture surface for damage and signs of polishing.

Polished spots on either the connecting rod or connecting rod cap mating surfaces indicate fretting and indicate that the rod must be replaced.

Dark areas on the face indicate carbonized oil deposits. Connecting rods with dark areas are reusable, if fretting is not present.

Polishing may be observed on the thrust face of the connecting rod  or rod cap, which is normal. Use the following procedure for inspection criteria. Refer to Procedure 001-007 in Section 1.

Inspect the connecting rod journal of the crankshaft for scratches or nicks.

Use a fine grit crocus cloth to remove the nicks and scratches.

Clean off any dust or debris released while using the crocus cloth.

Inspect the bearings for damage.

Replace any bearings with the following damage:

• Pitting
• Flaking
• Corrosion
• Lock tang damage
• Scratches (deep enough to be felt with a fingernail).

Normal bearing wear produces a smooth finish that will wear into the lining. Refer to the Parts Reuse Guidelines, Bulletin 3810303.

For more detailed information of bearing damage, refer to Analysis and Prevention of Bearing Failures, Bulletin 3810387.

Inspect the bearing seating surface for nicks or burrs.

If nicks or burrs can not be removed with a fine crocus cloth, the bearings must be replaced.

Clean off any dust or debris released while using the crocus cloth.

Crankshafts that are ground undersize in the connecting rod or the main bearing journals are marked on the front counterweight. If the crankshaft is marked, check the bearing shell part number to make sure the correct bearing size is used.

CAUTION  The connecting rod and bearing shell mating surfaces must be clean and dry when the bearing shells are installed. Used bearings must be installed in their original location or engine damage can occur.

Use clean Lubriplate™ 105 multi-purpose lubricant, or its equivalent, to lubricate the crankshaft journal mating surface of the upper bearing shell.

Install the upper bearing shell into the connecting rod with the tang of the bearing in the slot of the rod.

Install the bearing shell into the connecting rod cap with the tang (2) of the bearing in the slot (1) of the cap.

Use clean Lubriplate™ 105 multi-purpose lubricant, or its equivalent, to lubricate the bearing shell to the crankshaft journal mating surface.

CAUTION  Do not damage the fractured split surface on the connecting rod or connecting rod cap while the connecting rod caps are removed. If the fractured split surface is damaged, the connecting rod and connecting rod cap must be replaced to reduce the possibility of engine damage. Incorrect assembly can damage the rod.

NOTE: Make sure that the rod cap is installed only on the connecting rod from which it was removed and that the rod cap is properly oriented during installation.

NOTE: Both the rod cap and the connecting rod are serialized on one face to make sure of proper orientation

Install the cap onto the connecting rod.

NOTE: Minimize the number of joint interactions between the connecting rod and rod cap. There is only a finite number of times a connecting rod and rod cap can be assembled and removed before the joint loses its proper interaction.

Lubricate the threads and underside of the head of the connecting rod capscrews with clean engine oil.

Thread the capscrews into the connecting rod and hand tighten.

Tighten the capscrews in numerical sequence. Refer to Procedure 001-054 in Section 1.

Measure the connecting rod side clearance.

Connecting Rod Side Clearance

The connecting rod must move freely from side to side on the crankshaft journal. If the rod does not move freely, remove the rod cap and make sure the bearing shells are the correct size. Check for dirt or damage on the crankshaft and the bearing shells.

Repeat the above steps to install the remaining bearing shells and connecting rod caps.

CAUTION  The lubricating oil system must be primed before operating the engine after any internal engine repairs to reduce the possibility of internal component damage.

• Install the piston cooling nozzles. Refer to Procedure 001-046 in Section 1.
• Install the block stiffener plate. Refer to Procedure 001-089 in Section 1.
• Install the lubricating oil suction tube. Refer to Procedure 007-035 in Section 7.
• Install the oil transfer connection. Refer to Procedure 007-061 in Section 7.
• Install the lubricating oil pan. Refer to Procedure 007-025 in Section 7.
• Prime the lubricating oil system. Refer to Procedure 007-037 in Section 7.
• Operate the engine until it reaches normal operating temperature and check for leaks.