This procedure covers the removal, inspection, and replacement of connecting rod bearings on the 6.7L Cummins diesel engine, requiring complete engine disassembly including removal from the vehicle.

Warnings

Tools required

Parts

• Connecting rod bearing set (standard or oversized as measured) × 1 — Measure journals before ordering
• Connecting rod bolts (replace required) × 12 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Front cover gasket × 1 — Use OEM specification
• Rear main seal × 1 — Use OEM specification
• Valve cover gaskets × 1 — Use OEM specification
• Oil filter × 1 — Use OEM specification
• Coolant hoses and clamps as needed × 1 — Inspect during removal
• Exhaust manifold gaskets × 1 — Use OEM specification
• Intake manifold gaskets × 1 — Use OEM specification

Fluids

• Mopar 5W-20 Synthetic Blend — 13 qt
• Mopar OAT Coolant (Purple) — 18 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect both batteries (negative terminals first)
3. Drain engine oil and coolant into appropriate containers
4. Remove hood and set aside safely
5. Relieve fuel system pressure at fuel rail
6. Document all electrical connections and hose routing with photos
7. Label all fasteners and small parts by location during disassembly
8. Prepare clean workspace for engine disassembly on engine stand

Procedure

1. 1

   Remove engine from vehicle
   Remove intake air system, intercooler piping, and air filter housing. Disconnect all electrical connectors from engine including alternator, sensors, and injector harnesses. Disconnect fuel supply and return lines. Remove radiator, fan shroud, and cooling fan assembly. Disconnect exhaust system at turbocharger outlet. Remove transmission bellhousing bolts and separate transmission from engine (support transmission with jack). Attach engine hoist with chains to factory lift points. Remove engine mounting bolts and carefully lift engine from vehicle. Transfer engine to engine stand and secure properly.
2. 2

   Remove external components and accessories
   Remove turbocharger assembly and exhaust manifold. Remove intake manifold and fuel rail assembly. Remove valve cover. Disconnect and remove oil cooler lines. Remove alternator, A/C compressor, and power steering pump (leave hoses attached and secure aside). Remove water pump and thermostat housing. Remove harmonic balancer using puller tool. Remove front timing cover, being careful not to damage sealing surfaces.
   Torque spec

   Cover Bolts22 Nm (16 lb-ft)
3. 3

   Remove oil pan and oil pump
   With engine inverted on stand, remove oil pan bolts and carefully separate oil pan from block. Remove oil pump pickup tube and oil pump assembly. Clean all gasket surfaces thoroughly. Inspect oil pump screen for debris which may indicate bearing damage.
   Torque spec

   Gasket Bolts27 Nm (20 lb-ft)
4. 4

   Mark and remove connecting rod caps
   Rotate crankshaft to position cylinder 1 at bottom dead center. Using permanent marker or stamps, mark each connecting rod and cap with cylinder number if not already marked. Note that connecting rod caps are installed with specific orientation - mark the front side. Remove connecting rod cap bolts from cylinder 1. Carefully remove cap and bearing shell, keeping them together and labeled. Repeat for all six cylinders, keeping each rod cap with its corresponding rod.
   ⚠Rod caps and rods are matched pairs and cannot be interchanged between cylinders. Mark clearly before removal.
5. 5

   Remove pistons and connecting rods
   Check for ridge at top of cylinder bore. If present, remove with ridge reamer to prevent piston ring damage. Push piston and connecting rod assembly up and out through top of cylinder bore, being careful not to damage crankshaft journals with rod bolts (cover rod bolts with hose). Remove upper bearing shell from connecting rod. Place each piston assembly with its bearings and cap in labeled container. Repeat for all six cylinders.
   ⚠Protect crankshaft journals from damage by rod bolts during removal. Use rubber hose over bolt threads.
6. 6

   Inspect crankshaft and measure journals
   Clean all crankshaft journals thoroughly with solvent and lint-free cloth. Inspect each rod journal for scoring, discoloration, or damage. Using crankshaft journal micrometer, measure each rod journal diameter in four places (90-degree intervals) and in two planes to check for taper and out-of-round. Standard journal diameter is 2.7150-2.7157 inches. Maximum taper or out-of-round is 0.0002 inch. If journals are worn beyond standard size, crankshaft must be ground to undersize and corresponding undersize bearings used. Record all measurements.
   ⚠Crankshaft journals worn beyond specification or with excessive taper must be reground. Do not install new bearings on out-of-specification journals.
7. 7

   Inspect connecting rods and measure bores
   Clean connecting rods and caps thoroughly. Inspect rods for cracks, twisting, or damage (magnaflux inspection recommended). Install connecting rod caps with OLD bolts to their original rods in correct orientation (torque to 22 lb-ft only for measurement). Using dial bore gauge, measure connecting rod big end bore. Standard bore is 2.7986-2.7996 inches. Check for out-of-round and taper. If bore is out of specification, rods must be reconditioned or replaced. Remove caps after measurement.
   ℹ️Use old bolts for measurement and inspection only. New bolts will be installed during final assembly.
8. 8

   Select and fit new bearings
   Based on crankshaft journal measurements and connecting rod bore measurements, select appropriate bearing size (standard or undersize). Clean rod bores and bearing saddles thoroughly. Install new upper bearing shells into connecting rods (ensure bearing tang engages notch in rod). Install new lower bearing shells into connecting rod caps. Do not oil bearings yet - dry fit is required for Plastigage measurement.
   ℹ️Bearings are available in standard and various undersizes. Ensure correct size is ordered based on actual measurements.
9. 9

   Check bearing clearances with Plastigage
   Cut six strips of Plastigage to length of bearing width. Place one strip on each crankshaft rod journal (journals must be clean and dry). Install pistons/rods back onto crankshaft in numbered order. Install rod caps with NEW connecting rod bolts in correct orientation. Torque rod bolts to 22 lb-ft only (first step of torque sequence - DO NOT complete full torque sequence yet). Do not rotate crankshaft. Remove rod caps carefully and measure flattened Plastigage width using Plastigage envelope scale. Specified bearing clearance is 0.0012-0.0030 inch. If clearance is not within specification, determine cause and correct before proceeding. Remove Plastigage completely.
   ⚠️This is a measurement step only. Do not complete the full torque sequence or angle torque at this stage.
   ⚠Do not rotate crankshaft with Plastigage installed. This will give false readings.
   Torque spec

   Connecting Rod Bolts30 Nm (22 lb-ft) + 60°
10. 10

    Clean and oil bearings for final assembly
    Remove all pistons and connecting rods from crankshaft again. Remove all traces of Plastigage from bearings and journals using clean lint-free cloth. Inspect bearings one final time to ensure no debris or damage. Apply clean engine assembly lube or fresh engine oil liberally to all bearing surfaces (both upper and lower shells) and to crankshaft rod journals. Ensure oil holes in bearings align with oil holes in connecting rods.
    ⚠All Plastigage residue must be completely removed. Any residue left will contaminate the bearing oil film.
11. 11

    Install pistons and connecting rods to crankshaft
    Install piston ring compressor on piston number 1. Lubricate cylinder wall with engine oil. With crankshaft rod journal for cylinder 1 at bottom dead center, guide connecting rod with upper bearing installed through cylinder bore. Carefully tap piston through ring compressor into cylinder, guiding rod onto crankshaft journal (use rubber hose on rod bolts to protect journal). Position connecting rod on crankshaft journal. Install lower bearing shell into rod cap with light coat of assembly lube. Install rod cap in correct orientation matching cylinder number marks. Install NEW connecting rod bolts finger tight. Repeat process for all six cylinders in numerical order.
    ⚠️Use only NEW connecting rod bolts. Old bolts must never be reused as they are torque-to-yield design.
12. 12

    Torque connecting rod bolts - final sequence
    Starting with cylinder 1, torque connecting rod cap bolts using three-stage sequence: Stage 1: Torque to 22 lb-ft. Stage 2: Torque to 44 lb-ft. Stage 3: Tighten an additional 60 degrees using torque angle gauge. Ensure both bolts on each rod are torqued equally and sequentially. After completion, verify bolts do not back out. Repeat complete three-stage sequence for all six connecting rods. Rotate crankshaft by hand through two complete revolutions to ensure smooth rotation with no binding.
    ⚠️All three stages of the torque sequence must be completed in order. Angle torque is critical for proper bolt preload.
    ⚠If any binding or resistance is felt when rotating crankshaft, stop immediately and investigate cause.
    Torque spec

    Connecting Rod Bolts30 Nm (22 lb-ft) + 60°
13. 13

    Install oil pump and oil pan
    Prime oil pump with clean engine oil. Install oil pump assembly to engine block with new gasket. Install oil pump pickup tube with new O-ring, ensuring it is positioned correctly in oil pump. Clean oil pan and block mating surfaces thoroughly. Apply new oil pan gasket or RTV sealant per manufacturer specification. Install oil pan and torque bolts to specification in crisscross pattern. Allow RTV to cure per manufacturer instructions before filling with oil.
    Torque spec

    Gasket Bolts27 Nm (20 lb-ft)

    Mounting Bolts37 Nm (27 lb-ft)
14. 14

    Reassemble engine external components
    Install front timing cover with new gasket. Install harmonic balancer using installer tool (do not hammer). Install water pump and thermostat housing with new gaskets. Reinstall valve cover with new gasket. Install intake manifold, exhaust manifold, and turbocharger with new gaskets. Reinstall all accessories including alternator, A/C compressor, and power steering pump. Reconnect all sensors and electrical connections. Install new oil filter.
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)

    Mounting Bolts37 Nm (27 lb-ft)

    Sensor Bolts15 Nm (11 lb-ft)
15. 15

    Reinstall engine and complete assembly
    Remove engine from stand and attach to engine hoist. Carefully lower engine into vehicle, aligning with transmission bellhousing. Install engine mounting bolts and torque to specification. Reconnect transmission to engine. Reinstall radiator, cooling fan, and fan shroud. Reconnect exhaust system at turbocharger. Reconnect all fuel lines, hoses, and electrical connections per documentation. Fill engine with specified 13 quarts of Mopar 5W-20 Synthetic Blend oil. Fill cooling system with 18 quarts of Mopar OAT Purple coolant. Reconnect batteries (positive first). Reinstall hood.
    Torque spec

    Mounting Bolts37 Nm (27 lb-ft)
16. 16

    Prime oil system and initial startup
    Remove fuel pump fuse or relay to prevent engine start. Using oil pump priming tool through distributor port or by cranking engine, prime oil system until oil pressure is observed on gauge (minimum 15 psi at cranking speed). Reinstall fuel pump fuse. Perform final inspection of all connections. Start engine and monitor oil pressure immediately - pressure should reach minimum 10 psi within 15 seconds. Allow engine to idle and check for leaks. Monitor coolant temperature and oil pressure during warm-up. After engine reaches operating temperature, shut down and recheck all fluid levels and inspect for any leaks.
    ⚠️If oil pressure does not reach minimum specification within 15 seconds of startup, shut down immediately and investigate.
    ⚠Monitor engine closely during first startup. Any unusual noises, low oil pressure, or leaks require immediate shutdown.

Reassembly

1. Torque all fasteners to specification using multiple-stage sequences where required
2. Replace all gaskets, seals, and torque-to-yield bolts - never reuse
3. Apply assembly lubricant to all bearing surfaces before final installation
4. Verify crankshaft rotates freely by hand after rod cap installation and before proceeding
5. Double-check all bearing clearances are within specification before final assembly
6. Prime oil system thoroughly before initial startup

Verification

• Verify oil pressure reaches minimum 10 psi within 15 seconds of startup and maintains 25+ psi at idle when warm
• Check for any oil leaks at oil pan, front cover, and valve cover after startup
• Listen for any abnormal engine noises such as knocking or ticking that could indicate bearing problems
• Monitor engine temperature during test drive - should reach and maintain normal operating temperature
• After 500 miles, recheck oil level and condition, and inspect for any leaks
• Consider oil analysis after first oil change to verify proper bearing break-in and no excessive wear metals

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