Adjust valve lash clearances on the 6.7L Cummins diesel engine to maintain proper valve train operation and prevent premature wear or performance issues.

Warnings

Tools required

Parts

• Valve cover gasket × 1 — Use OEM Mopar gasket
• Valve cover bolt grommets × 1 — Use OEM specification
• Rocker housing gasket × 1 — Use OEM Mopar gasket if disturbed

Preparation

1. Ensure engine is completely cold (not run for at least 4 hours).
2. Disconnect both negative battery cables to prevent accidental starter engagement.
3. Remove engine cover and any intake components obstructing access to valve cover.
4. Label and disconnect any wiring harnesses, breather hoses, or fuel lines attached to valve cover.
5. Clean around valve cover thoroughly to prevent debris from entering engine.

Procedure

1. 1

   Remove valve cover
   Remove valve cover bolts in reverse sequence (outside to inside pattern). Carefully lift valve cover off, breaking gasket seal if necessary with a plastic pry tool. Inspect valve cover gasket and replace if damaged or hardened.
   Torque spec

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

   Rotate engine to TDC cylinder 1
   Using a socket on the crankshaft bolt, rotate the engine clockwise (viewed from front) until the timing mark on the camshaft gear aligns with the mark on the rocker housing for cylinder 1 TDC compression stroke. Both intake and exhaust valves for cylinder 1 should be closed (rocker arms loose). Verify piston is at top of stroke.
   ⚠Always rotate engine in normal direction of rotation only. Never turn engine backwards.
3. 3

   Check valve lash on cylinders 1, 2, and 4
   With engine at cylinder 1 TDC, use feeler gauges to check valve lash on cylinders 1, 2, and 4. Intake valves should have 0.010" clearance, exhaust valves should have 0.020" clearance. Insert feeler gauge between rocker arm and valve bridge. Proper clearance allows feeler gauge to slide with slight drag. Record measurements for each valve.
4. 4

   Adjust valves on cylinders 1, 2, and 4 if needed
   For any valve outside specification, loosen the valve adjusting screw lock nut while holding the adjusting screw with a second wrench. Turn the adjusting screw to achieve proper clearance, then hold the screw stationary while tightening the lock nut. Recheck clearance after tightening lock nut and readjust if necessary.
   ⚠Always hold adjusting screw stationary while tightening lock nut to prevent clearance change.
   Torque spec

   Valve Lash Adjusting Screw Lock Nut20 Nm (15 lb-ft)
5. 5

   Rotate engine 360 degrees to TDC cylinder 5
   Rotate crankshaft clockwise one complete revolution (360 degrees) until cylinder 5 is at TDC compression stroke. Verify timing marks align and both valves on cylinder 5 are closed (rocker arms loose).
6. 6

   Check valve lash on cylinders 3, 5, and 6
   With engine at cylinder 5 TDC, use feeler gauges to check valve lash on cylinders 3, 5, and 6. Intake valves should measure 0.010" and exhaust valves should measure 0.020". Record all measurements.
7. 7

   Adjust valves on cylinders 3, 5, and 6 if needed
   Adjust any valves outside specification using the same procedure as step 4. Loosen lock nut, adjust screw to achieve proper clearance, hold screw while tightening lock nut to specification, then verify clearance again.
   Torque spec

   Valve Lash Adjusting Screw Lock Nut20 Nm (15 lb-ft)
8. 8

   Verify all adjustments
   Rotate engine through two complete revolutions and recheck all valve clearances at their respective TDC positions to ensure adjustments held and lock nuts are properly torqued. Make any final corrections needed.
9. 9

   Clean gasket surfaces
   Thoroughly clean valve cover and rocker housing gasket surfaces with gasket scraper and solvent. Remove all old gasket material and ensure surfaces are completely clean and dry. Inspect for any damage or warping.
10. 10

    Install new valve cover gasket and reinstall cover
    Install new valve cover gasket and grommets on valve cover. Position valve cover carefully onto rocker housing, ensuring gasket seats properly. Install valve cover bolts finger tight, then torque in proper sequence (center outward pattern) to specification.
    ⚠Follow proper tightening sequence from center outward to prevent gasket distortion and oil leaks.
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)
11. 11

    Reinstall components and reconnect battery
    Reconnect all wiring harnesses, breather hoses, and fuel lines to valve cover. Reinstall any intake components and engine cover removed during disassembly. Reconnect battery cables.

Reassembly

1. Ensure all electrical connectors are fully seated and locked.
2. Verify no tools or parts were left in engine compartment.
3. Double-check that all fasteners were properly torqued per specifications.

Verification

• Start engine and verify no oil leaks from valve cover gasket.
• Listen for abnormal valve train noise. Properly adjusted valves should operate quietly without ticking or tapping sounds.
• Allow engine to reach operating temperature and verify no check engine lights or codes related to valve train operation.
• Recheck valve cover for leaks after first heat cycle and short test drive.

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