Complete replacement of the timing chain, guides, tensioner, and related components on the 6.7L Cummins diesel engine, requiring removal of front engine accessories and timing cover.

Warnings

Tools required

Parts

• Timing chain kit (includes chain, guides, tensioner) × 1 — Use OEM Cummins specification
• Timing cover gasket × 1 — Use OEM specification
• Front crankshaft seal × 1 — Use OEM specification
• Camshaft seal × 1 — Use OEM specification
• Valve cover gasket × 1 — Use OEM specification
• Oil drain plug crush washer × 1 — Use OEM specification
• Engine oil filter × 1 — Use OEM specification
• Timing cover bolt seals (if applicable) × 1 — Use OEM specification

Fluids

• Mopar 5W-20 Synthetic Blend — 13 qt
• Mopar OAT Coolant (Purple) — 4 qt

Preparation

1. Ensure vehicle is on level ground with parking brake applied and wheels chocked
2. Disconnect both battery cables (negative first, then positive) and secure away from terminals
3. Remove engine cover and air intake system
4. Place large drain pans under engine for oil and coolant collection
5. Allow engine to cool completely (minimum 2 hours after operation)
6. Take detailed photos of accessory belt routing and sensor locations before disassembly

Procedure

1. 1

   Drain fluids and remove accessories
   Drain engine oil completely using the drain plug with new crush washer for reinstallation. Drain coolant from radiator and block drain plugs into appropriate containers. Remove serpentine belt by releasing tensioner. Remove cooling fan assembly, fan shroud, and radiator upper hose. Disconnect all electrical connectors from alternator, power steering pump, and A/C compressor. Remove these accessories with brackets as needed for clearance.
2. 2

   Remove valve cover and upper engine components
   Disconnect fuel lines and mark all injector connections. Remove valve cover by removing bolts in reverse of tightening sequence. Label and remove all fuel injector connections, high-pressure fuel rails, and wiring harness brackets. Remove intake manifold if necessary for access. Clean valve cover mating surface thoroughly.
   ⚠Residual fuel pressure may be present. Have rags ready to catch any fuel spray when disconnecting fuel lines.
3. 3

   Remove crankshaft pulley and harmonic balancer
   Install crankshaft holding tool to prevent rotation. Remove crankshaft pulley bolt using breaker bar or impact wrench (note this is a very high torque fastener). Use harmonic balancer puller to remove balancer from crankshaft - do not use hammer or pry bar as this will damage the balancer. Inspect keyway and crankshaft snout for damage.
   ⚠The crankshaft pulley bolt requires significant force to remove. Ensure holding tool is properly secured before applying force.
4. 4

   Remove timing cover
   Remove all timing cover bolts noting their different lengths and locations. There are multiple bolt sizes: 6mm, 8mm, and 10mm bolts - keep them organized by size and location. Carefully pry timing cover away from engine block using plastic pry tools at designated pry points. Remove and discard timing cover gasket. Clean all gasket surfaces on block and cover with gasket scraper, being careful not to gouge aluminum surfaces.
   Torque spec

   Timing Cover Bolts12 Nm (9 lb-ft)
5. 5

   Verify and mark timing alignment
   Rotate crankshaft to Top Dead Center (TDC) for cylinder #1. Install timing pins into crankshaft and camshaft to verify proper alignment before chain removal. The crankshaft timing mark should align with the pointer on the block, and camshaft timing marks should align with marks on the cylinder head. Take multiple photos of timing marks and chain positioning. Mark the direction of chain rotation with paint marker.
   ⚠️Failure to properly mark and verify timing before disassembly can result in incorrect reassembly and engine damage. Double-check all timing marks.
6. 6

   Remove timing chain components
   Release timing chain tensioner by removing retaining bolt and extracting tensioner assembly. Remove timing chain guide bolts and extract guides. Note the position of all guides for reassembly. Remove camshaft sprocket bolt while holding camshaft with holding tool on the hex section behind the sprocket. Remove camshaft sprocket and timing chain as an assembly. Remove crankshaft sprocket using puller if necessary. Remove idler sprocket and inspect all components for wear.
   ⚠Hold camshaft firmly with wrench on hex section when removing sprocket bolt to prevent camshaft rotation and potential valve damage.
   Torque spec

   Timing Chain Tensioner25 Nm (18 lb-ft)

   Timing Chain Guide Bolts12 Nm (9 lb-ft)

   Camshaft Sprocket Bolts80 Nm (59 lb-ft)
7. 7

   Inspect components and prepare for reassembly
   Thoroughly inspect crankshaft and camshaft sprockets for wear, grooves, or damaged teeth. Check timing guides for excessive wear, cracking, or broken mounting tabs. Inspect tensioner for proper operation and oil leaks. Replace all worn components. Clean all timing chain cavity surfaces, removing all old gasket material, sealant, and debris. Verify oil pump pickup is clear and secured. Install new front crankshaft seal into timing cover using seal driver.
   ℹ️Any worn or damaged timing components must be replaced. Do not reuse stretched chains or worn guides.
8. 8

   Install crankshaft sprocket and idler
   Install crankshaft sprocket onto crankshaft ensuring keyway is properly aligned and sprocket is fully seated against crankshaft shoulder. Install idler sprocket onto engine block with mounting bolt, ensuring proper alignment. Torque idler sprocket bolt to specification. Verify crankshaft is still at TDC position.
9. 9

   Install timing chain and camshaft sprocket
   Position new timing chain around crankshaft sprocket with timing marks aligned. Route chain around idler sprocket and position camshaft sprocket onto chain with timing marks properly aligned. Install camshaft sprocket onto camshaft while maintaining chain position. Install camshaft sprocket bolt finger-tight. Verify all timing marks are properly aligned before final tightening. Hold camshaft with holding tool and torque sprocket bolt to specification. Apply medium-strength threadlocker as specified.
   ⚠️Triple-check timing mark alignment before final torquing. Incorrect timing will cause immediate engine damage upon startup.
   Torque spec

   Camshaft Sprocket Bolts80 Nm (59 lb-ft)
10. 10

    Install timing chain guides and tensioner
    Install timing chain guides in their original positions, ensuring mounting surfaces are clean and guides sit flush. Install guide bolts and torque to specification. Compress new timing chain tensioner and install retaining pin or clip to hold it in compressed position. Install tensioner assembly into engine block and torque mounting bolt to specification. Remove tensioner retaining pin to apply tension to chain. Manually rotate engine two complete revolutions and verify timing marks realign correctly.
    ⚠Ensure tensioner retaining pin is removed after installation or engine will not run properly. Verify tensioner has extended and is applying proper tension.
    Torque spec

    Timing Chain Guide Bolts12 Nm (9 lb-ft)

    Timing Chain Tensioner25 Nm (18 lb-ft)
11. 11

    Install timing cover with new gasket
    Install new timing cover gasket or apply RTV sealant according to manufacturer specifications to timing cover mating surface. Carefully position timing cover onto engine block, ensuring gasket remains properly seated. Install all timing cover bolts finger-tight, keeping bolts organized by size (6mm, 8mm, 10mm). Tighten bolts in proper sequence starting from center and working outward, torquing to specified values according to bolt size.
    ℹ️Follow proper tightening sequence as specified in service manual to prevent timing cover warpage and oil leaks.
    Torque spec

    Timing Cover Bolts12 Nm (9 lb-ft)
12. 12

    Install harmonic balancer and crankshaft pulley
    Clean crankshaft snout and apply light coat of engine oil to seal surface. Install harmonic balancer onto crankshaft, ensuring keyway is properly aligned. Tap balancer into place using soft mallet if necessary, ensuring it is fully seated. Install crankshaft pulley bolt and torque to specification using holding tool to prevent rotation. If bolt is torque-to-yield (TTY), follow manufacturer replacement and installation procedures.
    ⚠Verify if crankshaft pulley bolt is TTY type and requires replacement. Reusing TTY bolts can result in bolt failure.
13. 13

    Reinstall valve cover and engine accessories
    Install new valve cover gasket onto valve cover. Position valve cover onto cylinder head and install bolts finger-tight. Tighten valve cover bolts in proper sequence from center outward to specified torque in multiple passes. Reinstall fuel rails, injector connections, and all wiring harnesses according to labels and photos. Reinstall intake manifold if removed. Reinstall alternator, power steering pump, A/C compressor, and all brackets. Install serpentine belt according to routing diagram.
14. 14

    Refill fluids and final checks
    Install new oil filter and refill engine with 13 quarts of Mopar 5W-20 Synthetic Blend oil. Refill cooling system with Mopar OAT Purple coolant (approximately 4 quarts lost during procedure). Reconnect battery cables (positive first, then negative). Before starting engine, manually rotate crankshaft one complete revolution by hand using socket on crankshaft bolt to verify no binding or interference. Check for proper oil pressure using gauge or verify oil pressure light functions. Prime fuel system if necessary.
    ⚠Ensure crankshaft rotates freely by hand before attempting to start engine. Any binding indicates improper assembly.
15. 15

    Start engine and verify operation
    Start engine and immediately verify oil pressure is within normal range. Listen for any abnormal noises such as rattling or knocking. Allow engine to idle and reach operating temperature while monitoring for leaks around timing cover, valve cover, and all reinstalled components. Check for coolant leaks. Shut off engine and recheck fluid levels. Clear any diagnostic trouble codes that may have set during procedure. Test drive vehicle to verify normal operation under load.
    ⚠️If any abnormal noises are heard upon startup, immediately shut off engine and investigate. Continuing to run with timing issues will cause catastrophic damage.

Reassembly

1. Torque all fasteners to specifications in proper sequence using calibrated torque wrenches
2. Replace all gaskets and seals - never reuse timing cover gasket or valve cover gasket
3. Apply threadlocker to camshaft sprocket bolt as specified
4. Ensure tensioner retaining pin is removed after tensioner installation
5. Verify timing marks align correctly after rotating engine two complete revolutions
6. Route all wiring harnesses and fuel lines exactly as original installation using reference photos

Verification

• Engine starts immediately and runs smoothly with no unusual noises
• Oil pressure reaches normal operating range within 3-5 seconds of startup
• No oil leaks present around timing cover, valve cover, or front crankshaft seal after test drive
• No coolant leaks present around timing cover or water pump
• Engine idles smoothly and responds normally to throttle input
• No check engine light or diagnostic trouble codes related to timing or cam/crank correlation
• Verify proper engine performance under load during test drive

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