Rocker Arms - All

This procedure covers the removal and replacement of all rocker arms on the 5.9L Cummins I6 diesel engine, including valve cover removal, rocker lever assembly disassembly, and valve lash adjustment.

Warnings

Tools required

Parts

• Valve cover gasket × 1 — Use OEM specification
• Rocker arm assembly (if replacement needed) × 12 — Use OEM specification
• Rocker lever shaft bolts (if replacement needed) × 4 — Use OEM specification
• Valve adjustment screw lock nuts × 12 — Use OEM specification
• Injector connector tube seals × 6 — Use OEM specification

Fluids

• 15W-40 diesel oil or 5W-40 synthetic — 1 qt

Preparation

1. Ensure engine is completely cold before beginning work
2. Disconnect both negative battery cables
3. Remove engine cover if equipped
4. Position drip pan under engine to catch any oil spillage
5. Label and photograph all electrical connections and hose routing before removal
6. Have a clean workspace prepared to organize pushrods and rocker arms in order

Procedure

1. 1

   Remove valve cover
   Disconnect any wiring harnesses clipped to the valve cover. Remove the breather tube and any vacuum lines from the valve cover. Remove all valve cover bolts in a crisscross pattern from outside to inside. Carefully lift valve cover off, breaking the gasket seal with a plastic scraper if necessary. Avoid damaging the sealing surface on the cylinder head.
2. 2

   Remove injector lines and connectors
   The injector lines may interfere with rocker arm removal. Loosen and remove the injector line retaining clamps. Carefully disconnect the injector connector tubes from each injector. Cap all openings immediately to prevent debris entry. Note the routing and position of all lines for reinstallation.
3. 3

   Document valve positions
   Before removing any components, rotate the engine by hand using a socket on the crankshaft bolt to observe valve operation. Mark or photograph the rocker arm positions and pushrod arrangement. Number each rocker arm position from front to back (1-12) using masking tape on the valve cover rail.
4. 4

   Remove rocker lever shaft assemblies
   The 5.9L Cummins uses rocker lever pedestal assemblies for each cylinder. Remove the pedestal bolts (two per cylinder) that secure the rocker assemblies to the cylinder head. Work from the ends toward the center in a progressive loosening pattern to avoid binding. Lift the entire rocker shaft assembly straight up and off the pushrods. Keep the assembly together initially for reference.
5. 5

   Remove pushrods
   Carefully remove each pushrod from its bore, keeping them in exact order. Inspect each pushrod for wear, bending, or damage. Place pushrods in a numbered rack or cardboard holder in the correct sequence. Clean pushrods thoroughly and inspect the ball ends for wear or pitting. Replace any damaged pushrods.
6. 6

   Disassemble rocker shaft assembly
   If replacing individual rocker arms, carefully disassemble the rocker pedestal assemblies. Note the position and orientation of each rocker lever (intake vs exhaust) on its pivot shaft for each cylinder. The rocker arms are specific to intake and exhaust valves. Pay attention to oil feed holes in the shaft and their alignment. Keep all hardware organized by position.
7. 7

   Inspect all components
   Thoroughly inspect each rocker arm for wear on the valve stem contact pad, pushrod socket, and bore. Check for cracks, galling, or pitting. Inspect the rocker shaft for scoring, wear, or out-of-round conditions. Measure shaft diameter and rocker arm bore clearance if excessive wear is suspected. Replace any worn or damaged components as a set.
8. 8

   Clean and prepare cylinder head
   Clean the valve cover mating surface on the cylinder head using a plastic scraper. Remove all old gasket material without gouging the aluminum surface. Clean the rocker shaft mounting pedestals and bolt holes. Inspect valve stem tips for wear or mushrooming. Use compressed air to blow out oil passages in the head.
9. 9

   Reassemble rocker shaft assembly
   If disassembled, reassemble the rocker shaft with new or inspected components. Ensure rocker arms are in correct positions with intake and exhaust rockers properly oriented. Install spacers and springs in correct sequence. Verify oil feed holes in shaft are not blocked. Lubricate all components with clean engine oil during assembly.
10. 10

    Install pushrods
    Coat each pushrod with clean engine oil. Install pushrods in their original positions, ensuring the lower end seats properly in the lifter socket. Rotate each pushrod to verify it seats correctly and moves freely. Verify no pushrods are bent by rolling them on a flat surface before installation.
11. 11

    Install rocker shaft assemblies
    Position the rocker shaft assembly over the pushrods, carefully guiding each pushrod into its corresponding rocker arm socket. Ensure all pushrods are properly seated before lowering the assembly completely. Install the rocker shaft pedestal bolts finger-tight initially. Verify rocker arms align with valve stems and pushrods are correctly positioned.
12. 12

    Torque rocker shaft bolts
    Torque the rocker shaft pedestal bolts in a progressive sequence from the center outward. Since no factory torque specs are provided in the database, consult a service manual for the correct specification (approximately 37 ft-lbs for this engine). Torque in three progressive steps: 50%, 75%, then final torque. Verify rocker arms move freely after torquing.
13. 13

    Adjust valve lash
    The 5.9L Cummins requires valve lash adjustment. Rotate the engine to position the first cylinder at TDC compression stroke (both valves closed). Using a feeler gauge, check clearance between rocker arm and valve stem. Typical specification is 0.010" intake and 0.020" exhaust when cold. Loosen the adjustment screw locknut, adjust the screw to achieve proper clearance, and tighten locknut while holding the adjustment screw. Adjust the valves following the factory two-step method: with cylinder 1 at TDC compression, adjust the specified set of valves, then rotate the crankshaft 360 degrees and adjust the remaining valves. Consult the service manual for the exact valve set assignments.
14. 14

    Install valve cover
    Install a new valve cover gasket in the valve cover groove. Apply a small dab of RTV sealant at the front corners where the timing cover meets the cylinder head (if applicable). Position the valve cover carefully onto the cylinder head, ensuring the gasket remains properly seated. Install all valve cover bolts finger-tight, then torque in a crisscross pattern from center outward. Since no torque spec is provided in the database, consult a service manual for the correct low-value valve cover torque (verify exact spec before applying, as valve cover fasteners are torqued to a much lower value than block fasteners).
15. 15

    Reinstall injector lines and accessories
    Reinstall injector connector tubes with new seals. Torque injector line fittings carefully to avoid overtightening (consult service manual for specification). Reconnect all wiring harnesses, breather tubes, and vacuum lines per your documentation. Reconnect battery cables and install engine cover.

Reassembly

1. Double-check all torque specifications against a factory service manual
2. Verify all electrical connections are secure and properly routed
3. Ensure no tools or hardware are left in the engine compartment
4. Top off engine oil if any was lost during the procedure

Verification

• Before starting, rotate the engine by hand two complete revolutions to verify smooth operation and proper valve train function
• Start the engine and listen for any unusual valve train noise such as ticking or tapping
• Check for oil leaks around the valve cover gasket
• Allow engine to reach operating temperature and verify smooth idle with no misfires
• After the first heat cycle, recheck valve lash when engine is cold and readjust if necessary
• Monitor oil pressure gauge to ensure normal readings

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