Complete replacement of all piston rings on a 6.7L Cummins diesel engine, requiring engine removal, disassembly, cylinder honing, and reassembly with new rings.

Warnings

Tools required

Parts

• Piston ring set (complete for all 6 cylinders) × 1 — Use OEM specification
• Cylinder head gasket set × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Valve cover gasket × 1 — Use OEM specification
• Front cover gasket × 1 — Use OEM specification
• Rear main seal × 1 — Use OEM specification
• Oil pump pickup tube O-ring × 1 — Use OEM specification
• Connecting rod bolts (complete set) × 1 — Use OEM specification - TTY bolts
• Main bearing cap bolts (complete set) × 1 — Use OEM specification - TTY bolts
• Cylinder head bolts (complete set) × 1 — Use OEM specification - TTY bolts
• Engine oil drain plug crush washer × 1 — Use OEM specification
• Coolant × 1 — Mopar OAT Purple
• Engine oil filter × 1 — Use OEM specification
• Fuel filter × 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. Chock rear wheels.
2. Disconnect both battery cables (negative first, then positive) and remove batteries.
3. Drain engine coolant completely into appropriate containers.
4. Drain engine oil and remove oil filter.
5. Remove hood and store in safe location.
6. Remove front grille, radiator, intercooler, and A/C condenser assembly.
7. Discharge A/C system using proper recovery equipment (certified technician required).
8. Remove transmission from vehicle (required for engine removal access).
9. Label and disconnect all electrical connectors, vacuum lines, and fuel lines from engine.
10. Disconnect exhaust system at turbocharger outlet.
11. Remove turbocharger and intake manifold.
12. Support engine with hoist and remove engine mount bolts.
13. Carefully lift engine from vehicle and mount securely on engine stand.

Procedure

1. 1

   Remove cylinder heads
   Remove valve covers and rocker arm assemblies. Remove pushrods and mark them for reinstallation in original locations. Remove cylinder head bolts in reverse of tightening sequence (consult service manual for exact pattern). Carefully lift cylinder heads from block. Remove and discard old head gaskets. Clean all gasket surfaces thoroughly.
   Torque spec

   Cylinder Head Bolts65 Nm (48 lb-ft)
2. 2

   Remove oil pan and oil pump
   Remove oil pan bolts in reverse sequence and lower oil pan from engine. Remove oil pump pickup tube mounting bolt and remove pickup tube. Inspect pickup tube screen for debris. Remove front cover bolts and front cover assembly. Remove oil pump assembly from front of engine block.
   Torque spec

   Oil Pan Bolts12 Nm (9 lb-ft)

   Oil Pump Pickup Tube12 Nm (9 lb-ft)

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

   Remove crankshaft components and inspect
   Remove harmonic balancer using proper puller tool. Mark connecting rod caps with cylinder number and orientation before removal. Remove main bearing cap bolts in reverse sequence (outer bolts first, then inner bolts). Carefully remove main bearing caps and mark for position. Inspect crankshaft journals for scoring or damage. Measure all journals with micrometer and record measurements.
   Torque spec

   Main Bearing Cap Bolts75 Nm (55 lb-ft)
4. 4

   Remove pistons and inspect cylinders
   Rotate crankshaft to position piston at top dead center. Use ridge reamer to remove any ridge at top of cylinder bore (critical to prevent ring damage during removal). Remove connecting rod cap bolts and caps, keeping them matched with their rods. Push piston and rod assembly out through top of block using wooden dowel on rod bearing journal. Mark each piston with cylinder number. Repeat for all six cylinders. Inspect cylinder bores for scoring, taper, and out-of-round using dial bore gauge at multiple depths and orientations.
   ⚠Failure to remove cylinder ridge before piston removal will damage rings and piston ring lands.
   Torque spec

   Connecting Rod Bolts45 Nm (33 lb-ft)
5. 5

   Remove old rings and clean pistons
   Using piston ring removal tool, carefully expand and remove old rings from each piston starting with top compression ring, then second compression ring, then oil control ring assembly. Inspect piston ring grooves for wear, carbon buildup, or damage. Clean ring grooves thoroughly using old ring piece or proper groove cleaning tool. Clean pistons completely in solvent and inspect for cracks, especially around pin bosses. Check ring groove width with feeler gauges and compare to specifications.
   ⚠Do not use wire brush on piston ring grooves as this can damage the groove surfaces and cause premature ring wear.
6. 6

   Measure and hone cylinders
   Measure each cylinder bore at top, middle, and bottom in two perpendicular directions (six measurements per cylinder). Calculate taper and out-of-round for each cylinder. If measurements are within specification (consult service manual for limits, typically 0.002-0.003 inch), proceed with honing. Use ball-type or spring-loaded cylinder hone with 280-320 grit stones. Hone each cylinder using proper honing oil, moving hone up and down at rate to create 45-60 degree crosshatch pattern. Hone until all glazing is removed and consistent crosshatch is achieved. Re-measure cylinders after honing. Wash cylinders thoroughly with hot soapy water and dry immediately. Coat with clean engine oil.
   ⚠Excessive taper or out-of-round beyond specification requires cylinder boring and oversize pistons. Standard rings will not seal properly in worn cylinders.
   ℹ️Proper crosshatch angle is critical for ring seating and oil control. Too steep or too shallow will cause oil consumption.
7. 7

   Check and install new piston rings
   Insert each new ring into its corresponding cylinder bore (push with piston crown to square it in bore). Measure ring end gap with feeler gauge at multiple positions in cylinder. Top ring gap should be 0.016-0.024 inch, second ring 0.018-0.026 inch (verify exact specs in service manual). If gap is too tight, carefully file ring ends square on flat stone until correct gap is achieved. If gap is excessive, ring or cylinder is wrong size. Install rings on pistons using ring expander tool: first install oil control ring expander, then oil control rails (gaps 180 degrees apart), then second compression ring with mark facing up, then top compression ring with mark facing up. Stagger all ring end gaps around piston (typically 120 degrees apart, avoid aligning with pin bore).
   ⚠️Insufficient ring end gap will cause rings to butt together when heated, resulting in ring breakage and potential engine seizure.
   ⚠Ring orientation is critical. Top and second compression rings have specific top/bottom orientation marked on rings. Installation upside-down will cause oil consumption and poor sealing.
8. 8

   Install pistons into cylinders
   Coat cylinder walls, piston skirts, rings, and connecting rod bearings with clean engine assembly lube or oil. Install new connecting rod bearings in rods and caps (do not interchange). Verify rod orientation (numbers facing camshaft side). Install ring compressor over piston and compress all rings. Guide connecting rod into cylinder from top. Using wooden hammer handle, gently tap piston crown to drive piston into cylinder while ensuring ring compressor stays tight against block deck. Guide connecting rod onto crankshaft journal. Install rod cap in correct orientation and install new connecting rod bolts. Hand tighten bolts only at this stage. Repeat for all six cylinders.
   ⚠Never reuse TTY connecting rod bolts. Always install new bolts and follow torque-plus-angle procedure.
   ⚠Ensure rings do not catch on cylinder edge during installation. Catching and breaking rings is common during this step.
9. 9

   Torque connecting rod bolts
   With all pistons installed and rods on journals, torque connecting rod bolts on cylinder #1 to 33 lb-ft (45 Nm) in proper sequence. Then rotate each bolt an additional 90 degrees using angle gauge. Verify final bolt stretch is within specification using bolt stretch gauge. Rotate crankshaft two full revolutions by hand to verify smooth rotation. Repeat torque and angle procedure for remaining five cylinders. After all rods are torqued, rotate crankshaft several times and verify no binding occurs.
   ⚠️TTY bolts require both torque and angle specifications to be followed exactly. Incorrect tightening will result in bolt failure and catastrophic engine damage.
   Torque spec

   Connecting Rod Bolts45 Nm (33 lb-ft)
10. 10

    Install main bearing caps and crankshaft
    Install new main bearing inserts in block and caps (verify correct position and do not interchange). Coat bearings with assembly lube. Install main bearing caps in correct positions and orientation (refer to marks made during disassembly). Install new main bearing cap bolts. Torque main cap bolts to 55 lb-ft (75 Nm) in proper sequence (start with center main, then alternating outward). Then rotate each bolt an additional 90 degrees using angle gauge. Rotate crankshaft by hand to verify smooth rotation with no binding.
    ⚠️Main bearing cap bolts are TTY and must be replaced. Follow exact torque sequence specified in service manual to prevent crankshaft misalignment.
    Torque spec

    Main Bearing Cap Bolts75 Nm (55 lb-ft)
11. 11

    Reinstall oil pump and front cover
    Install oil pump assembly to front of block. Install front cover with new gasket, ensuring proper alignment. Torque cover bolts to 16 lb-ft (22 Nm) in proper sequence. Install oil pump pickup tube with new O-ring and torque mounting bolt to 9 lb-ft (12 Nm). Install harmonic balancer using proper installation tool (never hammer onto crankshaft).
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)

    Oil Pump Pickup Tube12 Nm (9 lb-ft)
12. 12

    Install oil pan
    Clean oil pan thoroughly and install new gasket or apply RTV sealant per manufacturer specifications. Position oil pan and install bolts hand-tight. Torque oil pan bolts to 9 lb-ft (12 Nm) in proper sequence (start at center and work outward in crossing pattern). Allow RTV to cure if used before filling with oil.
    Torque spec

    Oil Pan Bolts12 Nm (9 lb-ft)
13. 13

    Reinstall cylinder heads
    Verify cylinder head and block deck surfaces are completely clean and flat. Install new head gaskets with proper orientation (note front/rear and top markings). Carefully position cylinder heads onto block. Install new cylinder head bolts (TTY - must replace). Torque head bolts to 48 lb-ft (65 Nm) in proper sequence per service manual. Then rotate each bolt an additional 90 degrees, followed by final 90 degree rotation (total 180 degrees additional). Reinstall pushrods in original locations. Install rocker arm assemblies and adjust valves per service manual procedure.
    ⚠️Cylinder head bolts are TTY and require multi-stage torque sequence. Incorrect sequence or reusing old bolts will cause head gasket failure.
    ⚠Head gasket orientation is critical. Installing gaskets backwards or upside-down will cause coolant and oil leaks.
    Torque spec

    Cylinder Head Bolts65 Nm (48 lb-ft)
14. 14

    Complete engine reassembly and installation
    Install valve covers with new gaskets and torque bolts per specification. Reinstall turbocharger and intake manifold. Remove engine from stand and prepare for installation in vehicle. Reverse removal procedure to install engine, reconnecting all mounts, electrical connections, fuel lines, coolant hoses, and exhaust. Reinstall transmission. Install new oil filter and fill engine with 13 quarts of Mopar 5W-20 oil. Fill cooling system with 18 quarts of Mopar OAT Purple coolant. Reconnect batteries.
    Torque spec

    Oil Drain Plug35 Nm (26 lb-ft)

Reassembly

1. Verify all electrical connectors, vacuum lines, and coolant hoses are properly reconnected and secured
2. Double-check all torque specifications have been followed and angle rotations completed on TTY bolts
3. Ensure all drain plugs are installed with new crush washers and properly torqued
4. Prime oil system by cranking engine with fuel shut-off solenoid disconnected until oil pressure registers
5. Check for any coolant, oil, or fuel leaks before extended running

Verification

• Start engine and verify oil pressure registers within 15 seconds (should show 10+ PSI at idle when warm)
• Allow engine to reach operating temperature and verify cooling system is functioning properly with no leaks
• Listen for abnormal noises such as knocking, rattling, or excessive valve train noise
• Monitor engine for first 20 minutes of operation for any leaks, unusual sounds, or overheating
• Perform initial break-in procedure: vary engine speed and load for first 500 miles, avoid sustained high RPM or heavy loads
• Change engine oil and filter after first 500 miles of operation to remove break-in debris
• After 1000 miles, re-check valve lash adjustment as new rings may affect valve train geometry slightly
• Monitor oil consumption over first 3000 miles - some initial consumption is normal during ring seating
• Watch for blue smoke from exhaust (indicates oil consumption) or excessive blow-by from crankcase vent

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