Valve Spring - Single

This procedure covers replacement of a single valve spring on the 5.9L Cummins diesel engine, requiring removal of the valve cover, rocker assembly, and use of a valve spring compressor while maintaining proper valve timing.

Warnings

Tools required

Parts

• Valve spring × 1 — Use OEM specification
• Valve cover gasket × 1 — Use OEM specification
• Valve stem seals (if replacing) × 1 — Use OEM specification
• Valve keepers/locks (inspect, replace if damaged) × 2 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect both battery terminals (negative first) to prevent accidental starter engagement
3. Allow engine to cool completely for at least 2 hours if recently operated
4. Gather all tools and parts before beginning
5. Clean external valve cover area to prevent debris entry
6. Identify which cylinder requires spring replacement and verify you can rotate engine to position that cylinder appropriately

Procedure

1. 1

   Remove valve cover
   Remove any electrical connectors, fuel lines, or breather hoses attached to the valve cover. Remove the valve cover bolts in reverse of tightening sequence (working from outside toward center). Carefully lift valve cover off, breaking the gasket seal with gentle prying if necessary. Inspect gasket condition and replace if reusing is not advisable.
   Torque spec

   Valve Cover Bolts10 Nm (7 lb-ft)
2. 2

   Rotate engine to position affected cylinder
   Rotate the crankshaft using a breaker bar on the crank pulley bolt (clockwise from front of engine) to position the affected cylinder at TDC on the compression stroke. Both intake and exhaust valves should be fully closed with rocker arms loose. This prevents valve-to-piston contact during spring removal. Verify piston position using the crankshaft damper timing marks or engine barring tool, or by confirming both rocker arms are loose (base circle) for the affected cylinder.
   ⚠Confirm both valves are closed before proceeding. Opening a valve while piston is at TDC can result in piston contact damage.
3. 3

   Remove rocker arm assembly for affected valve
   Identify the rocker arm for the valve requiring spring replacement. Note the orientation and position for reassembly. Loosen and remove the rocker arm shaft/pedestal mounting bolts as required to free the rocker for the affected valve (on 12-valve engines rockers are mounted on a shaft assembly; on 24-valve engines individual rocker pedestals apply). The camshaft lobe should be pointing away from the rocker arm (base circle position). Lift the rocker arm assembly off the cylinder head and set aside in a clean area. Remove the pushrod and store upright to maintain oil coating.
   ℹ️Keep pushrods in order if removing multiple rocker assemblies. They must be reinstalled in their original positions.
   Torque spec

   Rocker Arm Bolts30 Nm (22 lb-ft)
4. 4

   Install valve spring compressor
   Position the valve spring compressor tool over the valve spring assembly. Ensure the compressor is properly seated on both the spring retainer and a stable surface (either the cylinder head deck or a bridge adapter depending on tool design). Verify the tool is aligned squarely to prevent slipping during compression.
   ⚠Improper tool positioning can cause the compressor to slip under load, potentially causing injury or dropping valve keepers into the engine.
5. 5

   Compress valve spring and remove keepers
   Slowly compress the valve spring by tightening the compressor tool. Apply just enough pressure to relieve tension on the valve keepers (split locks). Using a magnetic pickup tool, carefully remove both valve keepers from the valve stem groove. Place keepers immediately in a parts tray. Inspect keepers for wear or damage. Once keepers are removed, slowly release spring compressor pressure and remove the tool.
   ⚠️Keep hands and face clear of spring retainer when releasing compressor. Unexpected release can cause retainer to fly off with significant force.
6. 6

   Remove valve spring components
   Remove the valve spring retainer, valve spring, and spring seat (if equipped). Inspect all components for wear, cracking, or damage. If replacing the valve stem seal, use appropriate seal removal tool or carefully pry old seal off valve guide. Note the orientation of all components for correct reassembly. Keep valve from falling into cylinder by stuffing clean shop rags into the port, or by applying compressed air through the injector bore (this is a diesel engine with no spark plugs) to hold the valve seated.
   ⚠Do not allow the valve to drop into the cylinder. If valve falls, cylinder head removal will be required for retrieval.
7. 7

   Inspect valve and guide
   With spring removed, carefully pull the valve up to inspect the stem for scoring, wear, or damage. Check valve guide for excessive play by gently rocking the valve laterally. Excessive movement indicates guide wear. Inspect valve face and seat condition visually. If valve stem seal replacement is needed, install new seal over valve guide using appropriate driver or seal installation tool, ensuring it seats fully.
   ℹ️If valve guide wear is excessive or valve is damaged, this repair may not be sufficient and cylinder head service may be required.
8. 8

   Install new valve spring assembly
   Install the spring seat (if equipped) over the valve guide. Install the new valve spring with the correct orientation (closer-wound coils typically face the cylinder head). Place the valve spring retainer over the spring. Ensure the valve is fully seated against its seat in the cylinder head before proceeding. Verify spring orientation. Installing backwards can affect proper spring seating and lead to premature failure or coil bind.
   ℹ️Verify spring orientation. Installing backwards can affect valve timing and engine performance.
9. 9

   Compress spring and install keepers
   Reinstall the valve spring compressor and slowly compress the new spring until the keeper grooves on the valve stem are fully exposed above the retainer. Using a small amount of assembly grease to hold them in place, carefully position both valve keepers into the valve stem groove. Ensure keepers are fully seated in the groove and properly positioned. Slowly release the spring compressor while verifying keepers remain seated. Once pressure is released, tap the valve stem tip gently with a plastic tool to ensure keepers are locked in place.
   ⚠Verify both keepers are fully seated before releasing spring pressure. Improperly seated keepers will release when engine starts, causing catastrophic valve damage.
10. 10

    Reinstall pushrod and rocker arm
    Reinstall the pushrod in its original position, seating it fully in the lifter socket. Rotate the crankshaft if necessary to position the camshaft lobe on base circle (pointing away from rocker arm position). Position the rocker arm assembly with the pushrod seated in the rocker socket and the valve-end properly aligned over the valve stem tip. Install and hand-tighten the rocker arm bolt.
    ⚠Ensure camshaft lobe is on base circle (pointing away) before tightening rocker arm bolt to specification. Tightening with lobe at peak can damage components.
    Torque spec

    Rocker Arm Bolts30 Nm (22 lb-ft)
11. 11

    Adjust valve lash (if applicable)
    The 5.9L Cummins requires valve lash adjustment. With the engine positioned so the camshaft lobe is on base circle for this valve, use feeler gauges to check clearance between rocker arm and valve stem. Valve lash specification varies by engine variant and must be verified against the correct Cummins service data for this specific year: the 12-valve (1994–1998) is typically 0.010 in intake / 0.020 in exhaust cold, while the 24-valve (1998.5–2007) is typically 0.010 in intake / 0.020 in exhaust cold — confirm exact values in the factory manual before adjusting. Adjust by loosening the rocker arm bolt, turning the adjusting screw, then retightening to specification while holding adjustment. Verify final clearance after torquing.
    ℹ️Incorrect valve lash will cause poor performance, excessive noise, or valve damage. Take time to set precisely.
    Torque spec

    Rocker Arm Bolts30 Nm (22 lb-ft)
12. 12

    Clean gasket surfaces
    Thoroughly clean both the cylinder head and valve cover gasket mating surfaces using a plastic gasket scraper. Remove all old gasket material, oil residue, and debris. Wipe surfaces clean with lint-free rags and solvent. Inspect surfaces for damage, warping, or deep scratches that could prevent proper sealing. Do not use aggressive metal scrapers that can gouge the cast-iron head or valve cover sealing surfaces, as gouges can lead to oil leaks.
    ⚠Do not use metal scrapers on aluminum surfaces as they can cause gouges that lead to oil leaks.
    Torque spec

    Gasket Surface Bolts20 Nm (15 lb-ft)
13. 13

    Install valve cover with new gasket
    Position the new valve cover gasket on the cylinder head, ensuring it is properly seated in the gasket groove or locating features. Carefully lower the valve cover onto the cylinder head, aligning all bolt holes. Install all valve cover bolts hand-tight first, then torque in the specified sequence (from center outward) to specification. Reconnect any electrical connectors, breather hoses, or fuel lines that were removed.
    ⚠Over-tightening valve cover bolts can distort the cover and cause oil leaks. Use a torque wrench and follow the tightening sequence.
    Torque spec

    Valve Cover Bolts10 Nm (7 lb-ft)
14. 14

    Reconnect battery and perform initial start
    Reconnect battery terminals (positive first, then negative). Before starting, verify all tools are removed from engine compartment and all connections are secure. Start the engine and allow it to idle. Immediately check for oil leaks around the valve cover gasket. Listen for abnormal valve train noise that could indicate improper rocker arm installation or valve lash adjustment.
    ⚠If excessive valve train noise is heard or oil leaks are observed, shut down engine immediately and reinspect the repair.

Reassembly

1. Valve cover bolts must be torqued in sequence from center outward to ensure even gasket compression
2. Verify valve lash adjustment is correct after engine reaches operating temperature and recheck if necessary
3. All rocker arm bolts must be torqued with the camshaft lobe pointing away from the rocker arm
4. Ensure all electrical connectors and breather hoses are fully reconnected and secured

Verification

• Start engine and verify no oil leaks from valve cover gasket after 5-10 minutes of operation
• Listen for proper valve train operation with no excessive clicking, tapping, or rattling noises
• Verify engine runs smoothly without misfires or rough idle on the repaired cylinder
• Recheck valve lash adjustment after engine reaches full operating temperature to confirm proper clearance
• Monitor oil consumption over next several hundred miles to ensure valve stem seal is functioning properly if replaced

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