Camshaft R&R

Complete removal and installation of the camshaft on the 5.9L Cummins I6 diesel engine, including valve train disassembly, timing gear removal, and cam bearing inspection.

Warnings

Tools required

Parts

• Camshaft × 1 — Use OEM specification or performance upgrade
• Cam bearing set × 1 — Inspect and replace as needed
• Timing gear set (cam and crank) × 1 — Inspect and replace as needed
• Front cover gasket × 1 — OEM or equivalent
• Valve cover gasket × 1 — OEM or equivalent
• Fuel pump gasket × 1 — If equipped with mechanical pump
• Pushrod set × 1 — Inspect and replace if worn or bent
• Tappet/lifter set × 1 — Recommended replacement with cam
• Oil pump drive gear × 1 — Inspect for wear
• Front crankshaft seal × 1 — OEM or equivalent
• Oil filter × 1 — Standard oil change item
• Engine assembly lube × 1 — Camshaft installation lubricant
• RTV silicone sealant × 1 — High-temp anaerobic
• Harmonic balancer bolt × 1 — One-time-use recommended

Fluids

• 15W-40 diesel oil or 5W-40 synthetic — 12 qt
• HOAT coolant 50/50 — 28 qt

Preparation

1. Park vehicle on level surface and engage parking brake. Chock rear wheels.
2. Disconnect both negative and positive battery cables.
3. Drain engine oil completely and remove oil filter.
4. Drain cooling system into appropriate container.
5. Remove engine cover and air intake system.
6. Remove intercooler and charge air piping if equipped.
7. Label and disconnect all electrical connectors from valve cover area.
8. Remove accessory drive belts.
9. Install engine support fixture or attach engine hoist to lift eyes on cylinder head.
10. Create a labeled storage system for pushrods (must maintain original positions).
11. Clean work area and ensure adequate lighting for precision work.

Procedure

1. 1

   Remove valve cover and rocker assembly
   Remove valve cover bolts and lift off valve cover. Remove rocker arm pedestal bolts in reverse order of tightening sequence (outside to inside). Carefully remove rocker arm assemblies and set aside. Note the position and orientation of each component.
2. 2

   Remove pushrods and tappets
   Remove all 12 pushrods and place them in numbered order in your organizer. Inspect each pushrod for wear, bending, or scoring. Using a magnetic pickup tool or lifter removal tool, extract all tappets from their bores. Keep tappets in order if reusing (though replacement is recommended with camshaft replacement). Inspect tappet faces for pitting, scoring, or concave wear patterns.
3. 3

   Remove front-mounted accessories
   Remove power steering pump and bracket (secure aside without disconnecting hoses). Remove A/C compressor and bracket (secure aside without disconnecting lines). Remove coolant pump. Remove oil fill tube. Remove crankshaft pulley and harmonic balancer using appropriate puller tool. Remove any remaining accessories blocking access to front timing cover.
4. 4

   Support engine and adjust position
   Using engine hoist or support fixture, slightly raise engine. Remove or loosen motor mount bolts as necessary. Remove the cooling package (radiator, fan, condenser/charge-air cooler) as needed to provide front clearance, as the camshaft is removed out the FRONT of the block through the timing gearcase. Ensure engine is securely supported and stable before proceeding. Ensure engine is securely supported and stable before proceeding.
5. 5

   Remove timing gear cover
   Remove all timing gear cover bolts (approximately 16 bolts of varying lengths - note positions). Carefully pry cover away from block using appropriate pry points. Remove and discard front cover gasket and front crankshaft seal. Clean all sealing surfaces thoroughly.
6. 6

   Verify and mark timing alignment
   Rotate crankshaft until timing marks on cam gear and crank gear are aligned (marks should face each other). Mark gear positions with paint or punch marks as additional reference. Take photographs for reassembly reference. This engine is a Common Rail (CR) engine with a Bosch CP3 injection pump; there is no cam-timed mechanical injection pump on this vehicle, so mechanical pump timing verification does not apply.
7. 7

   Remove fuel injection pump if equipped
   This engine is a Common Rail engine, so the P-pump/VP44 injection pump removal does not apply. The CP3 high-pressure pump is gear-driven from the timing gearcase; if timing cover removal requires it, disconnect and cap all high-pressure fuel lines and remove the CP3 per service manual. Note the lift pump is in-tank (electric), not engine-mounted.
8. 8

   Remove camshaft thrust plate and timing gear
   Remove the two camshaft thrust plate bolts accessible through holes in cam gear. Note thrust plate shim thickness for reassembly reference. Using appropriate gear puller or press, carefully remove camshaft gear from camshaft. Avoid damaging camshaft threads or gear keyway. Remove Woodruff key from camshaft and store safely.
9. 9

   Remove camshaft from engine
   Thread long camshaft installation bolts into front of camshaft or use dedicated camshaft handle tool. Very carefully slide camshaft straight out of engine block, ensuring cam lobes do not contact or damage cam bearings. Support camshaft weight at all times - never allow it to hang unsupported. An assistant is highly recommended for this step. Rotate camshaft as needed to clear lobes through bearings.
10. 10

    Inspect cam bearings and journals
    Thoroughly inspect all camshaft journals for scoring, wear, or discoloration. Measure journal diameters with micrometer. Inspect cam bearings in block for wear, scoring, or damage. Check bearing clearances using Plastigage if reusing bearings (specification typically 0.001-0.003 inches). Replace cam bearings if any wear or out-of-spec conditions exist. Use cam bearing tool to remove and install bearings, ensuring oil holes align correctly.
11. 11

    Prepare and lubricate new camshaft
    Thoroughly clean new or reground camshaft with solvent and compressed air. Inspect all lobes and journals for defects. Coat all camshaft lobes liberally with camshaft assembly lube (not standard engine oil). Coat all journals with assembly lube or engine oil. Coat new cam bearings with assembly lube if just installed.
12. 12

    Install camshaft
    Attach installation tool or bolts to front of camshaft. Very carefully slide camshaft into engine block, rotating as necessary to prevent lobe contact with bearings. Support camshaft weight at all times. Work slowly and deliberately - rushing this step can destroy cam bearings. Once fully inserted, install thrust plate with original or new shims. Install thrust plate bolts finger-tight.
13. 13

    Check and adjust camshaft end play
    Install dial indicator against camshaft end. Push and pull camshaft to measure end play. Specification should be verified in the Cummins ISB 5.9L service manual (typically approximately 0.005-0.010 inches). Adjust by changing thrust plate shim thickness if necessary. Once correct end play is achieved, tighten thrust plate bolts. Install Woodruff key in camshaft keyway.
14. 14

    Install timing gears and set timing
    Heat new camshaft gear in oven or hot water to expand (200-250°F). Slide heated gear onto camshaft, ensuring keyway aligns. Allow to cool completely. Install crankshaft gear if removed. Rotate crankshaft until crank gear timing mark is at 12 o'clock. Rotate camshaft until cam gear timing mark aligns with crank gear mark (marks facing each other). Verify timing mark alignment is precise. Install injection pump drive gear if applicable, aligning timing marks.
15. 15

    Complete reassembly
    Install new front crankshaft seal. Apply thin bead of RTV to front cover mating surface per manufacturer instructions. Install front cover with new gasket, ensuring proper bolt sequence. Install harmonic balancer and new bolt. Reinstall coolant pump, power steering pump, A/C compressor, and all accessories. Reinstall fuel injection pump with timing marks aligned if applicable. Coat new or existing tappets with assembly lube and install in original bores. Install pushrods in original positions with assembly lube on ends. Install rocker assemblies and adjust valve lash per the Cummins ISB 5.9L service manual specification (verify intake and exhaust lash values for this engine). Install valve cover with new gasket. Reconnect all electrical connections, hoses, and belts. Return engine to normal position and torque motor mounts.

Reassembly

1. Use new gaskets and seals throughout reassembly - do not reuse old gaskets.
2. Follow proper bolt tightening sequences for valve cover and front cover to prevent leaks.
3. Valve lash must be set to proper specifications after camshaft installation (typically 0.010 inches intake, 0.020 inches exhaust on cold engine, but verify for your specific camshaft).
4. Prime oil system before starting engine by cranking with fuel shutoff solenoid disconnected or fuel system disabled.
5. Double-check all timing mark alignments before installing front cover.
6. Ensure all electrical connectors are fully seated and locked.
7. Verify all accessories are properly mounted and belt tensions are correct.

Verification

• Refill engine with correct amount and specification of diesel engine oil (12 quarts).
• Refill cooling system with HOAT coolant 50/50 mixture (28 quarts) and bleed air from system.
• Reconnect battery cables.
• Perform initial start with close observation - oil pressure should register within 10 seconds.
• Listen for abnormal valve train noise (ticking, knocking, or rattling indicates problems).
• Check for oil and coolant leaks at front cover, valve cover, and all gasket surfaces.
• Allow engine to reach normal operating temperature and recheck for leaks.
• Road test vehicle under light load and verify normal operation.
• Recheck valve lash after 500 miles of operation and adjust if necessary.
• Monitor oil pressure and engine temperature during first several hundred miles.
• Avoid heavy loads or high RPM operation for first 500 miles during camshaft break-in period.

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