Complete disassembly, inspection, machining, and reassembly of the 6.7L Cummins diesel engine including replacement of all wear components, gaskets, seals, and bearings with precision measurement and torque-to-yield fastener procedures.

Warnings

Tools required

Parts

• Complete engine gasket set × 1 — Use OEM Cummins specification
• Main bearing set (standard or oversized as measured) × 1 — Size determined by crankshaft measurement
• Connecting rod bearing set (standard or oversized) × 1 — Size determined by crankshaft measurement
• Piston ring set (6 cylinders) × 1 — Use OEM Cummins specification
• Cylinder head bolts (TTY - must replace) × 1 — Use OEM Cummins TTY bolts
• Main bearing cap bolts (TTY - must replace) × 1 — Use OEM Cummins TTY bolts
• Connecting rod bolts (TTY - must replace) × 1 — Use OEM Cummins TTY bolts
• Timing chain kit with guides and tensioner × 1 — Use OEM Cummins specification
• Oil pump assembly × 1 — Replace if wear exceeds specification
• Water pump × 1 — Use OEM specification
• Thermostat × 1 — Use OEM specification
• Oil cooler seals × 1 — Use OEM specification
• Camshaft position sensor × 1 — Replace during rebuild
• Crankshaft position sensor × 1 — Replace during rebuild
• Valve stem seals × 1 — Use OEM specification
• Freeze plugs (core plugs) - complete set × 1 — Use OEM specification
• Front and rear crankshaft seals × 1 — Use OEM specification
• Oil filter × 1 — Mopar 68157291AA or equivalent
• Fuel filter/water separator × 1 — Mopar 68197867AA or equivalent
• Exhaust manifold studs and nuts × 1 — Replace if corroded

Fluids

• Mopar 5W-20 Synthetic Blend engine oil — 13 qt
• Mopar OAT Coolant (Purple) — 18 qt
• Assembly lube for engine bearings — 1 qt
• Diesel fuel for priming system — 2 qt

Preparation

1. Disconnect both batteries and remove from vehicle to prevent accidental engagement
2. Drain all engine fluids including oil, coolant, and fuel filter
3. Remove hood and secure properly to allow overhead clearance for engine removal
4. Remove radiator, intercooler, charge air cooler, and all cooling system components
5. Disconnect all electrical connectors, labeling each with tape and marker
6. Disconnect exhaust system at turbocharger outlet
7. Remove turbocharger assembly and disconnect all intake plumbing
8. Disconnect fuel lines at injection pump and common rail, cap all openings immediately
9. Remove alternator, A/C compressor, power steering pump (leave hoses attached and secure aside)
10. Support transmission with jack and remove bellhousing bolts
11. Attach engine hoist with grade-8 bolts to factory lifting points on engine
12. Remove engine mount bolts and carefully extract engine from vehicle
13. Mount engine securely on heavy-duty engine stand using bellhousing bolt holes
14. Clean exterior of engine thoroughly before disassembly to prevent contamination

Procedure

1. 1

   Remove external components and accessories
   With engine on stand, remove valve covers, intake manifold, exhaust manifolds, fuel injection components (common rail, injectors, high pressure pump), oil pan, oil pump, timing cover, and all external sensors. Clean and inspect all removed components for reuse viability. Remove and inspect EGR cooler and oil cooler assemblies.
2. 2

   Remove cylinder head and inspect
   Rotate engine to TDC on cylinder #1. Remove rocker arm assembly and pushrods, keeping them organized by cylinder position. Remove cylinder head bolts in reverse of tightening sequence (outside to inside). Carefully lift cylinder head from block using pry points only at designated areas. Send cylinder head to machine shop for complete valve job, pressure testing, surface milling if needed, and valve guide/seat inspection. Check head bolt holes in block for damage and chase threads.
3. 3

   Remove pistons and connecting rod assemblies
   Mark each connecting rod cap and rod with cylinder number and orientation using number stamps. Use ridge reamer to remove any ridge at top of cylinder bores. Remove connecting rod cap bolts and carefully push piston and rod assemblies out through top of block. Keep caps matched to their respective rods. Inspect cylinder bores for scoring, taper, and out-of-round using dial bore gauge at top, middle, and bottom positions.
4. 4

   Remove crankshaft and main bearings
   Remove flywheel/flexplate. Mark main bearing caps with cylinder number and orientation. Remove main bearing cap bolts in stages working from outside to center. Carefully lift crankshaft from block and place on clean padded surface. Remove main bearings from block and caps, keeping them organized. Measure crankshaft journals with micrometer for wear, taper, and out-of-round. Record all measurements for machine shop.
5. 5

   Remove camshaft and balance shaft
   Remove camshaft thrust plate bolts. Carefully slide camshaft forward out of block, supporting it to avoid damaging bearings or lobes. Remove balance shaft following same procedure. Inspect camshaft lobes for wear and measure cam lift. Inspect camshaft bearings in block for scoring or excessive wear. Remove and replace freeze plugs using punch and hydraulic press with proper installation tools.
6. 6

   Clean and inspect engine block
   Thoroughly clean engine block using hot tank or pressure washer with appropriate solvent. Clean all oil passages with rifle brush and compressed air. Inspect block for cracks using magnetic particle inspection or dye penetrant testing. Measure cylinder bores with dial bore gauge and record taper and out-of-round measurements. Take block to machine shop for cylinder honing or boring if measurements exceed 0.002 inch taper or 0.001 inch out-of-round. Have main bearing saddles checked for alignment and surface finish.
7. 7

   Inspect and prepare crankshaft
   Have crankshaft magnafluxed for cracks at machine shop. If journal measurements show wear beyond 0.001 inch taper or 0.0005 inch out-of-round, have crankshaft ground to next undersize. Verify oil passage cleanliness by running rifle brush through all passages and flushing with solvent. Check crankshaft end play specification and select appropriate thrust bearing. Polish journals with 400-grit emery cloth if within specification.
8. 8

   Prepare pistons and connecting rods
   Use hydraulic press to remove piston pins and separate pistons from rods. Inspect pistons for cracking around pin bosses and ring lands. Remove old piston rings using ring expander tool. Have piston ring grooves cleaned professionally. Inspect connecting rods for straightness and twist using alignment fixture at machine shop - replace if bent. Have rod big end bores checked and resized if necessary. Install new piston pins using press and ensure smooth operation without binding.
9. 9

   Install main bearings and crankshaft
   Ensure block and bearing saddles are completely clean and dry. Install upper main bearings into block saddles, ensuring bearing tabs engage notches. Lubricate bearings with assembly lube. Carefully lower crankshaft into block. Install lower bearings into main caps with assembly lube. Install main caps in correct positions matching marks made during disassembly. Install NEW main bearing cap bolts. Tighten main bearing cap bolts to initial torque specification in sequence from center main outward, then apply additional angle as specified in three stages. Check crankshaft end play with dial indicator - should be 0.005-0.012 inch. Verify crankshaft rotates freely by hand.
   ⚠Main bearing cap bolts are TTY and must be replaced with new bolts - reuse will cause bearing failure
   Torque spec

   Main Bearing Cap Bolts75 Nm (55 lb-ft)
10. 10

    Install piston rings and measure end gap
    Place each piston ring into its corresponding cylinder bore at bottom of ring travel area. Use piston to square ring in bore. Measure ring end gap with feeler gauge - top compression ring should be 0.012-0.022 inch, second compression ring 0.018-0.028 inch, oil control ring 0.010-0.030 inch. File ring ends if gap is too tight. Install rings on pistons using ring expander tool with top ring marking facing up. Install top compression ring, second compression ring, then oil control ring assembly. Stagger ring end gaps 120 degrees apart.
11. 11

    Install piston and rod assemblies
    Install upper connecting rod bearings with assembly lube. Lubricate cylinder bores, piston skirts, and rings with engine oil. Install piston ring compressor on piston. Orient piston with valve reliefs toward intake side of engine. Insert connecting rod into cylinder from above and carefully tap piston into bore using rubber mallet handle while guiding rod onto crankshaft journal. Install lower rod bearing with assembly lube. Install rod cap in correct orientation matching disassembly marks. Install NEW connecting rod bolts and hand tighten. Repeat for all six cylinders.
12. 12

    Torque connecting rod bolts and verify bearing clearance
    Before final torque, use Plastigage to verify bearing clearance on at least two cylinders. Apply Plastigage strip across journal, install cap with bolts torqued to specification, then remove cap and measure crushed Plastigage width - clearance should be 0.0012-0.0031 inch. Once clearance is verified, tighten all connecting rod cap bolts to 45 Nm (33 ft-lb), then apply additional torque angle as specified (typically 60 degrees). Verify each rod has side clearance of 0.005-0.013 inch using feeler gauge. Rotate crankshaft two full revolutions by hand to ensure no binding.
    ⚠Connecting rod bolts are TTY design - must use new bolts and apply torque angle precisely
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
13. 13

    Install camshaft and balance shaft
    Lubricate camshaft bearings and lobes with assembly lube or engine oil additive designed for flat tappet cams. Carefully slide camshaft into block, supporting shaft to prevent bearing damage. Install camshaft thrust plate and tighten bolts. Measure camshaft end play with dial indicator - should be 0.002-0.010 inch. Install balance shaft using same lubrication procedure and verify end play. Install camshaft bearing caps and tighten camshaft cap bolts in sequence from center outward in three passes to final torque of 14 Nm (10 ft-lb).
    Torque spec

    Camshaft Cap Bolts14 Nm (10 lb-ft)

    Balance Shaft Bolts25 Nm (18 lb-ft)
14. 14

    Install timing chain, guides, and tensioner
    Install crankshaft timing gear if removed. Position crankshaft at TDC for cylinder #1. Install camshaft timing gear with marks aligned. Install timing chain ensuring timing marks on crank and cam gears align per factory specification. Install timing chain guides and tighten guide bolts to 12 Nm (9 ft-lb). Compress timing chain tensioner and install retaining pin. Install tensioner and tighten bolt to 25 Nm (18 ft-lb), then remove retaining pin to activate tensioner. Rotate engine two complete revolutions and verify timing marks realign perfectly.
    ⚠️Incorrect timing will cause piston-to-valve contact and catastrophic engine damage upon startup
    Torque spec

    Timing Chain Guide Bolts12 Nm (9 lb-ft)

    Timing Chain Tensioner Bolt25 Nm (18 lb-ft)
15. 15

    Install oil pump and oil pan
    Prime oil pump by packing with petroleum jelly. Install oil pump to block and tighten oil pump bolts to 12 Nm (9 ft-lb). Install oil pump pickup tube with new O-ring and tighten to 12 Nm (9 ft-lb). Ensure pickup tube is positioned 5/16 to 1/2 inch from bottom of oil pan. Clean oil pan and block mating surfaces thoroughly. Apply thin bead of RTV sealant to oil pan corners and install new oil pan gasket. Install oil pan and tighten oil pan bolts in spiral pattern from center outward to 12 Nm (9 ft-lb). Install new oil drain plug with new crush washer and tighten to 35 Nm (26 ft-lb).
    Torque spec

    Oil Pump Bolts12 Nm (9 lb-ft)

    Oil Pump Pickup Tube12 Nm (9 lb-ft)

    Oil Pan Bolts12 Nm (9 lb-ft)

    Oil Drain Plug35 Nm (26 lb-ft)
16. 16

    Install timing cover and front seal
    Clean timing cover and block mating surfaces. Install new front crankshaft seal into timing cover using seal driver. Apply thin bead of RTV sealant where timing cover meets oil pan rail. Position timing cover on block with new gasket. Install timing cover bolts (8mm) and tighten in sequence to 25 Nm (18 ft-lb). Install crankshaft pulley/harmonic balancer using installation tool to prevent seal damage. Install crankshaft pulley bolt and tighten to 180 Nm (133 ft-lb) - may require impact wrench.
    ℹ️Crankshaft pulley bolt may be TTY specification - verify with factory service manual if additional angle is required
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)

    Crankshaft Pulley Bolt180 Nm (133 lb-ft)
17. 17

    Install cylinder head and valve train
    Verify cylinder head surface is clean and flat from machine shop. Install new head gasket on block with orientation markings visible (do not use sealant on multi-layer steel gasket). Carefully position cylinder head on block using alignment dowels. Install NEW cylinder head bolts with light oil on threads and under bolt heads. Tighten cylinder head bolts in sequence from center outward in multiple stages: first to 30 Nm (22 ft-lb), then to 65 Nm (48 ft-lb), then apply angle torque as specified (typically 90 degrees in two 45-degree steps). Install pushrods in original locations. Install rocker arm assembly and adjust valve lash per specification.
    ⚠Cylinder head bolts are TTY design - must replace with new bolts and follow exact torque sequence and angle specifications
    Torque spec

    Cylinder Head Bolts65 Nm (48 lb-ft)
18. 18

    Install exhaust and intake manifolds
    Apply anti-seize compound to new exhaust manifold studs and install. Position exhaust manifold gaskets and install manifolds. Tighten exhaust manifold nuts in pattern working from center outward to 30 Nm (22 ft-lb). Clean intake manifold mating surface on cylinder head. Install new intake manifold gaskets and position intake manifold. Tighten intake manifold bolts in sequence from center outward to 25 Nm (18 ft-lb). Install EGR cooler with new gaskets.
    Torque spec

    Exhaust Manifold Nuts30 Nm (22 lb-ft)

    Intake Manifold Bolts25 Nm (18 lb-ft)
19. 19

    Install valve covers and external components
    Install new valve cover gaskets in valve covers. Position valve covers on cylinder head and tighten valve cover bolts in sequence from center outward to 10 Nm (7 ft-lb). Install rear crankshaft seal using seal driver. Install flywheel with new bolts, aligning dowel pins. Tighten flywheel bolts in star pattern to 95 Nm (70 ft-lb). Install oil cooler with new seals. Install water pump with new gasket. Install all sensors including camshaft position sensor and crankshaft position sensor, tightening sensor bolts to 15 Nm (11 ft-lb). Install turbocharger with new gaskets.
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)

    Flywheel Bolts95 Nm (70 lb-ft)

    Sensor Bolts15 Nm (11 lb-ft)
20. 20

    Prepare engine for installation
    Install all remaining external components including alternator, A/C compressor, power steering pump with mounting bolts to specified torque. Install new oil filter and fuel filter/water separator. Rotate engine by hand two complete revolutions to verify no interference or binding. Double-check all bolt torques and verify no tools or parts are left in engine. Install engine into vehicle using hoist, reconnect engine mounts, transmission, exhaust, all electrical connectors, fuel lines, cooling system, and intake plumbing.
    Torque spec

    Mounting Bolts64 Nm (47 lb-ft)

Reassembly

1. Fill engine with 13 quarts of Mopar 5W-20 Synthetic Blend oil and install new oil filter
2. Fill cooling system with 18 quarts of Mopar OAT (Purple) coolant mixed 50/50 with distilled water
3. Prime fuel system by cycling ignition key to run position multiple times without cranking to pressurize system
4. Reconnect both batteries ensuring positive terminals are secured and protected
5. Bleed air from cooling system using bleeder valves while engine is at operating temperature
6. Check all fluid levels and inspect for leaks before initial startup

Verification

• Before starting engine, rotate crankshaft by hand at least two full revolutions to verify smooth rotation with no binding or interference
• Perform initial startup and idle for 20 minutes monitoring oil pressure (should reach 10 PSI within 15 seconds), coolant temperature, and unusual noises
• Check for oil, coolant, fuel, and exhaust leaks during warm-up period
• Verify no misfire codes or check engine lights after initial startup
• After initial break-in period (first 500 miles), change oil and filter, retorque cylinder head bolts if specified by manufacturer, and readjust valve lash
• Monitor oil consumption and coolant levels for first 1000 miles to identify any potential issues
• Perform compression test after break-in period - all cylinders should be within 10% of each other and meet specification (typically 350-400 PSI)
• Test drive vehicle under varying loads and verify proper power delivery, no excessive smoke, and stable engine operation

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