Complete removal and replacement of all six pistons in the 6.7L Cummins diesel engine, including disassembly of cylinder head, timing components, oil pan, and crankshaft connecting rods.

Warnings

Tools required

Parts

• Piston and pin assembly × 6 — Use OEM specification
• Piston ring set (complete) × 6 — Use OEM specification
• Connecting rod bearing set × 6 — Use OEM specification
• Main bearing set (if inspected) × 1 — Use OEM specification
• Cylinder head gasket set × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Front cover gasket × 1 — Use OEM specification
• Rear main seal × 1 — Use OEM specification
• Connecting rod bolts (TTY) × 12 — Use OEM specification
• Cylinder head bolts (TTY) × 1 — Use OEM specification
• Main bearing cap bolts (TTY) × 1 — Use OEM specification
• Oil filter × 1 — Mopar 68157291AA or equivalent
• Engine oil drain plug crush washer × 1 — Use OEM specification
• Timing cover seals × 1 — Use OEM specification
• Valve cover gaskets × 1 — Use OEM specification
• Intake manifold gaskets × 1 — Use OEM specification
• Exhaust manifold gaskets × 1 — Use OEM specification

Fluids

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

Preparation

1. Position vehicle on level surface and engage parking brake. Place wheel chocks at rear wheels.
2. Disconnect both battery cables (negative first) and remove batteries.
3. Drain engine oil completely and remove oil filter.
4. Drain coolant from radiator and engine block drain plugs.
5. Remove hood for clearance and access.
6. Relieve fuel system pressure by disconnecting fuel rail pressure sensor.
7. Label and disconnect all electrical connectors, vacuum lines, and wiring harnesses from engine.
8. Remove air intake system, intercooler, and all charge air piping.
9. Disconnect exhaust system from turbocharger and remove exhaust.
10. Disconnect fuel lines from fuel filter housing and injection pump.
11. Remove radiator, fan shroud, and cooling fan assembly.
12. Remove power steering pump and A/C compressor (leave hoses attached and secure aside).
13. Disconnect transmission from engine and support transmission with jack.
14. Remove transfer case if necessary for clearance.
15. Attach engine hoist with load leveler to engine lifting points.
16. Remove engine mount bolts and carefully extract engine from vehicle.
17. Mount engine securely on engine stand and position for disassembly.

Procedure

1. 1

   Remove External Components
   With engine on stand, remove all remaining external components: turbocharger, oil cooler, fuel injection pump, fuel rails and injectors (label cylinder positions), alternator, starter, oil filter housing, dipstick tube, water pump, thermostat housing, and all brackets. Remove valve covers and inspect valve train for damage. Store all components in organized manner with labels.
2. 2

   Remove Cylinder Head
   Remove rocker arm assemblies and pushrods (label positions for reinstallation). Loosen cylinder head bolts in reverse of tightening sequence (from outside toward center). Remove cylinder head bolts completely. Carefully lift cylinder head off engine block using proper lifting technique or hoist if available. Inspect head gasket surface on both head and block. Place cylinder head on clean padded surface. Cover head to prevent debris entry.
3. 3

   Remove Timing Components
   Rotate crankshaft to TDC position for cylinder #1. Mark timing gear positions before removal. Remove front timing cover bolts and carefully remove cover. Remove camshaft gear bolt while preventing camshaft rotation. Remove camshaft gear and timing chain or gears as equipped. Remove crankshaft gear using appropriate puller if necessary. Inspect all timing components for wear.
   Torque spec

   Cover Bolts22 Nm (16 lb-ft)
4. 4

   Remove Oil Pan and Pump
   Remove oil pan bolts in crisscross pattern and carefully separate oil pan from block using gasket scraper if necessary. Remove oil pump pickup tube mounting bolt and remove pickup tube. Inspect pickup screen for debris. Remove oil pump mounting bolts and extract oil pump assembly. Clean all gasket surfaces thoroughly on block and oil pan.
   Torque spec

   Oil Pan Bolts12 Nm (9 lb-ft)

   Oil Pump Pickup Tube12 Nm (9 lb-ft)
5. 5

   Inspect and Remove Cylinder Ridge
   Rotate engine on stand to access cylinders from below. Check top of each cylinder bore for ridge formation. Using cylinder ridge reamer, carefully remove ridge from top of each cylinder following tool manufacturer instructions. Never allow reamer to cut into piston ring travel area. Clean all metal shavings completely from cylinders using lint-free cloth and solvent. Inspect cylinder walls for scoring or damage requiring machine work.
6. 6

   Remove Pistons and Connecting Rods
   Rotate crankshaft to position piston at bottom dead center. Mark connecting rod caps and rod positions with cylinder number using permanent marker (1-6). Remove connecting rod cap bolts and carefully remove rod caps. Push piston and rod assembly up and out through top of cylinder bore, supporting piston to prevent damage. Install rod cap back on connecting rod to prevent mixing. Repeat for all six cylinders. Place assemblies on clean work surface in order.
7. 7

   Disassemble and Measure Old Pistons
   Using piston ring expander, carefully remove old piston rings from each piston. Remove piston pins using appropriate press or pin removal tool. Separate pistons from connecting rods. Measure old piston diameter at thrust faces 90 degrees to pin bore. Measure piston pin bore diameter. Inspect connecting rods for cracks, bend, or twist using appropriate gauges. Document all measurements for comparison with new parts.
8. 8

   Measure and Inspect Cylinder Bores
   Using dial bore gauge, measure each cylinder bore at three heights (top, middle, bottom) and in two directions (parallel and perpendicular to crankshaft). Calculate taper and out-of-round for each cylinder. Compare measurements to service manual specifications. If any cylinder exceeds wear limits or has damage, cylinder block requires machining. Record all measurements. Clean cylinder bores with solvent and dry thoroughly.
9. 9

   Inspect Crankshaft and Main Bearings
   With pistons removed, inspect crankshaft rod journals for scoring or damage. Measure each rod journal diameter with micrometer at multiple points. Check for out-of-round and taper. Inspect main bearing surfaces in similar manner if performing complete bearing inspection. If crankshaft shows wear beyond specification, it requires grinding and undersize bearings. Check crankshaft endplay using dial indicator. Document all measurements.
10. 10

    Prepare and Install New Piston Rings
    Verify new pistons are correct part numbers for this engine. Measure new piston diameter and compare to cylinder bore measurements to verify proper piston-to-bore clearance (typically 0.0025-0.0055 inches for diesel). Install new piston rings on new pistons using ring expander tool. Install oil control ring first (expander and rails), then second compression ring, then top compression ring. Verify ring end gaps are positioned 120 degrees apart. Check ring side clearance in piston grooves.
11. 11

    Install New Connecting Rod Bearings
    Clean connecting rod bearing saddles thoroughly with lint-free cloth and solvent. Install new connecting rod bearing inserts into rods and caps, ensuring bearing tangs seat properly in notches. Do not mix bearing halves or positions. Lubricate bearings generously with clean engine assembly lube or engine oil. Check bearing clearance using Plastigage method: place Plastigage on journal, install cap with NEW bolts to specified initial torque only (do not complete angle torque), remove cap and measure Plastigage width. Proper clearance is typically 0.0015-0.0035 inches.
12. 12

    Install Pistons into Cylinders
    Install new piston pins into pistons and connecting rods per manufacturer instructions, ensuring proper orientation (piston valve reliefs toward intake side). Lubricate cylinder walls, pistons, and rings thoroughly with engine oil. Install piston ring compressor on piston, compressing all rings fully. Orient piston correctly for engine (valve reliefs toward intake, any markings toward front). Guide connecting rod into cylinder bore first, carefully tapping piston with wooden hammer handle to seat into bore. Repeat for all six pistons.
13. 13

    Torque Connecting Rod Caps
    Rotate crankshaft to position piston being worked on at bottom dead center. Ensure connecting rod bearing surfaces and crankshaft journal are clean and lubricated. Install connecting rod cap in correct orientation matching marked positions. Install NEW connecting rod bolts (TTY type). Hand tighten bolts, then torque to 45 Nm (33 lb-ft) initial specification. Using torque angle gauge, rotate bolts additional angle specified in service manual (typically 90 degrees). Verify rod side clearance on crankshaft journal (typically 0.006-0.014 inches). Repeat for all six connecting rods.
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
14. 14

    Install Oil Pump and Oil Pan
    Install oil pump assembly with new gasket onto engine block, aligning with crankshaft drive. Torque oil pump mounting bolts to specification. Install oil pump pickup tube with new O-ring seal and torque pickup tube bolt. Clean oil pan and block gasket surfaces thoroughly. Apply new oil pan gasket or RTV sealant per manufacturer specification. Install oil pan and hand start all bolts. Torque oil pan bolts in crisscross pattern from center outward.
    Torque spec

    Mounting Bolts64 Nm (47 lb-ft)

    Oil Pump Pickup Tube12 Nm (9 lb-ft)

    Oil Pan Bolts12 Nm (9 lb-ft)
15. 15

    Install Timing Components
    Install crankshaft gear onto crankshaft snout, ensuring proper seating. Apply new front cover seal. Align camshaft gear with crankshaft gear according to timing marks. Install timing chain or gears ensuring marks are properly aligned for correct valve timing. Install camshaft gear bolt and torque to specification. Rotate crankshaft two complete revolutions and verify timing marks realign correctly. Install front timing cover with new gasket and torque cover bolts.
    Torque spec

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

    Install Cylinder Head
    Clean cylinder head and block mating surfaces completely, ensuring no old gasket material remains. Inspect surfaces for warpage using straight edge. Install new head gasket onto block, ensuring proper orientation (markings up and toward front). Carefully lower cylinder head onto block, aligning dowel pins. Install NEW cylinder head bolts (TTY type) and hand tighten all bolts. Following manufacturer torque sequence (typically from center outward), torque all bolts to initial 65 Nm (48 lb-ft). Using angle gauge, complete angle torque sequence per service manual (typically 90 degrees, wait, then additional angle). Install pushrods in original positions and install rocker assemblies. Adjust valves to specification.
    Torque spec

    Cylinder Head Bolts65 Nm (48 lb-ft)
17. 17

    Reinstall External Components
    Install valve covers with new gaskets. Reinstall all external components in reverse order of removal: thermostat housing, water pump, dipstick tube, oil filter housing, starter, alternator, fuel injection pump, fuel rails with injectors in correct cylinder positions, oil cooler, and turbocharger. Use new gaskets and seals throughout. Install new oil filter. Torque all mounting hardware to specifications. Install oil drain plug with new crush washer.
    Torque spec

    Mounting Bolts64 Nm (47 lb-ft)

    Gasket Bolts27 Nm (20 lb-ft)

    Sensor Bolts15 Nm (11 lb-ft)

    Oil Drain Plug35 Nm (26 lb-ft)
18. 18

    Install Engine and Reconnect Systems
    Remove engine from stand and attach to engine hoist with load leveler. Carefully lower engine into vehicle, aligning engine mounts and transmission bellhousing. Install engine mount bolts and torque to specification. Reconnect transmission and install transfer case if removed. Reconnect exhaust system. Install A/C compressor and power steering pump. Reinstall radiator, fan shroud, and cooling fan. Reconnect all fuel lines, vacuum lines, electrical connectors, and wiring harnesses using labels for reference. Install intercooler and complete air intake system. Install hood.
    Torque spec

    Mounting Bolts64 Nm (47 lb-ft)
19. 19

    Fill Fluids and Prime Engine
    Fill engine with 13 quarts Mopar 5W-20 synthetic blend engine oil. Fill cooling system with 18 quarts Mopar OAT Purple coolant. Prime fuel system by cycling ignition on/off multiple times without cranking to allow fuel pump to pressurize system. Check for fuel leaks at all connections. Bleed air from cooling system per manufacturer procedure. Reconnect batteries (positive first, then negative).

Reassembly

1. All torque-to-yield (TTY) bolts including connecting rod bolts, main bearing cap bolts, and cylinder head bolts must be replaced with new bolts and must not be reused.
2. Follow exact torque sequences specified in service manual for cylinder head and main bearing caps to prevent warpage.
3. After initial startup, allow engine to reach operating temperature and check for leaks at all gasket surfaces.
4. Perform initial oil change at 500 miles following engine rebuild to remove any assembly residue.
5. Double-check all electrical connections, fuel lines, and coolant hoses are secure before starting engine.

Verification

• Before starting engine, manually rotate crankshaft several complete revolutions to verify no binding or interference. Rotation should be smooth.
• Check engine oil level on dipstick and verify proper level after filling.
• Check coolant level after bleeding air and verify proper level.
• Start engine and listen for abnormal noises. Engine should start and run smoothly without knocking or unusual sounds.
• Monitor oil pressure gauge immediately at startup. Oil pressure should rise within 5-10 seconds to normal range (10+ PSI at idle).
• Allow engine to idle and warm up while monitoring for any oil, fuel, or coolant leaks.
• Check for exhaust leaks at manifold connections.
• After warm-up, verify cooling fans operate correctly and engine reaches normal operating temperature without overheating.
• Perform test drive and monitor engine performance, oil pressure, and temperature under load conditions.
• After 500-mile break-in period, inspect all torqued connections and check for any leaks or issues.

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