Replace a single valve spring on the 6.7L Cummins diesel engine by removing the valve cover, rotating the engine to compress the valve, and installing a new spring without removing the cylinder head.

Warnings

Tools required

Parts

• Valve spring (single) × 1 — Use OEM specification
• Valve cover gasket × 1 — Use OEM specification
• Valve keeper set (2 half-moon keepers) × 1 — Use OEM specification
• Rocker arm bolt (if damaged) × 1 — Use OEM specification

Preparation

1. Disconnect both negative battery cables
2. Allow engine to cool completely if recently operated
3. Remove engine cover and any interfering intake ducting
4. Identify which cylinder and valve requires spring replacement
5. Clean area around valve cover to prevent debris entry

Procedure

1. 1

   Remove valve cover
   Disconnect any wiring harnesses, breather tubes, or fuel line clips attached to the valve cover. Remove valve cover bolts in reverse sequence (work from outside toward center). Carefully lift valve cover off and set aside. If gasket is stuck, gently pry at designated pry points only.
   Torque spec

   Cover Bolts22 Nm (16 lb-ft)
2. 2

   Rotate engine to neutral position for affected valve
   Using a 27mm socket on the crankshaft bolt, rotate the engine clockwise (viewed from front) until the cam lobe for the affected valve is pointing away from the rocker arm (base circle position). This removes spring pressure and allows rocker arm removal. Verify valve is fully closed before proceeding.
   ⚠Only rotate engine in normal direction of rotation (clockwise from front) to prevent timing issues
3. 3

   Remove rocker arm assembly
   Remove the rocker arm mounting bolt for the affected valve. Lift the rocker arm and pedestal assembly straight up and off the valve stem. Inspect rocker arm and valve stem tip for unusual wear. Store rocker components in clean area to prevent contamination.
   Torque spec

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

   Compress valve spring and remove keepers
   Install valve spring compressor tool over the valve spring, ensuring it is centered and stable. Slowly compress the spring until the valve keepers (half-moon collets) are accessible. Using magnetic pickup tool, carefully remove both valve keepers and place in secure location. Slowly release spring compressor pressure slightly but keep tool in place.
   ⚠️Valve spring is under significant tension - maintain firm grip on compressor tool at all times
   ⚠If valve drops into cylinder after keeper removal, the valve seal may be damaged requiring additional repair
5. 5

   Remove valve spring retainer and spring
   With spring still slightly compressed, remove the valve spring compressor tool. Lift off the valve spring retainer (upper collar). Remove the valve spring from the cylinder head. Inspect valve stem seal for damage - if spring failed catastrophically, seal may need replacement.
   ℹ️Inspect old spring for cracks, breaks, or signs of overheating that indicate root cause of failure
6. 6

   Clean and inspect valve stem
   Clean the valve stem thoroughly with shop towel. Inspect valve stem for scoring, wear, or damage. Check that valve moves freely in guide by gently pushing down on valve (it should spring back). If valve binds or shows excessive wear, additional repair is required beyond spring replacement.
   ⚠Do not allow valve to drop into cylinder - maintain light upward pressure or use vacuum to hold in place
7. 7

   Install new valve spring
   Place new valve spring over valve stem with closer-wound coils toward cylinder head (spring is directional). Install valve spring retainer on top of spring. Verify retainer seats properly on spring.
   ℹ️Valve springs have tighter pitch coils on one end - verify correct orientation per service manual
8. 8

   Compress spring and install keepers
   Using valve spring compressor, compress new spring until keeper grooves on valve stem are fully exposed. Apply small amount of grease to keeper grooves to hold keepers in place during installation. Carefully position both valve keepers in the grooves using magnetic tool. Verify keepers are fully seated in their grooves before releasing pressure.
   ⚠️Ensure both keepers are completely seated before releasing compressor or spring can eject keepers violently
9. 9

   Release spring compressor and verify keeper engagement
   Very slowly release valve spring compressor pressure while watching keepers. They should remain locked in grooves as retainer contacts them. Once fully released, tap valve stem tip gently with plastic tool - keepers should not move. Remove compressor tool. Gently attempt to lift spring retainer - it should be firmly locked by keepers.
   ⚠If keepers do not lock properly, spring must be recompressed and keepers repositioned
10. 10

    Reinstall rocker arm assembly
    Verify cam lobe is still positioned away from rocker arm (base circle). Place rocker arm and pedestal assembly back onto valve stem and cylinder head. Install rocker arm bolt and tighten to specification. Ensure rocker arm moves freely and contacts valve stem tip properly.
    ⚠Rocker arm bolt must be tightened only when cam lobe is pointing away from rocker to prevent valve damage
    Torque spec

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

    Clean gasket surfaces and install valve cover
    Clean valve cover and cylinder head gasket surfaces thoroughly with gasket scraper and solvent. Install new valve cover gasket in cover groove. Position valve cover onto cylinder head carefully to avoid gasket displacement. Install all valve cover bolts hand-tight, then torque in sequence (center outward) to specification.
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)
12. 12

    Reconnect components and batteries
    Reconnect all wiring harnesses, breather tubes, and fuel line clips to valve cover. Reinstall any intake ducting or engine covers removed. Reconnect both negative battery cables. Clear any diagnostic codes if present.

Reassembly

1. Double-check all fasteners are tightened to specification before starting engine
2. Verify no tools or parts are left in engine compartment
3. Ensure all electrical connections and hoses are properly secured

Verification

• Start engine and listen for unusual valve train noise from repaired cylinder
• Check for oil leaks around valve cover gasket
• Allow engine to reach operating temperature and verify smooth idle
• Perform test drive and monitor for any engine performance issues or warning lights
• Re-check valve cover bolt torque after first heat cycle if possible

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