Replace valve stem seals on the 6.7L Cummins diesel engine to stop oil consumption through worn valve guides without removing the cylinder head.

Warnings

Tools required

Parts

• Valve stem seal set (12 intake + 12 exhaust) × 1 — OEM Cummins valve stem seal kit
• Valve cover gasket × 1 — Use OEM specification
• Front cover gasket × 1 — Use OEM specification
• RTV silicone gasket maker (Mopar or equivalent) × 1 — High-temp RTV
• Engine oil × 1 — 13 quarts capacity for refill
• Oil filter × 1 — Use OEM specification
• Fuel filter (if draining system) × 1 — Use OEM specification

Fluids

• Mopar 5W-20 Synthetic Blend — 13 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect both negative and positive battery cables to prevent accidental starter engagement
3. Remove engine cover and beauty covers for access to valve cover
4. Drain engine coolant if any coolant hoses obstruct valve cover removal
5. Drain engine oil completely and remove oil filter
6. Remove air intake system from turbocharger to air filter housing
7. Disconnect all electrical connectors, breather hoses, and fuel lines attached to valve cover
8. Label and photograph all wiring harness routing for reassembly reference
9. Clean entire valve cover and cylinder head area to prevent contamination during disassembly

Procedure

1. 1

   Remove valve cover assembly
   Remove all valve cover bolts in reverse of tightening sequence (outside to inside pattern). Carefully lift valve cover away from cylinder head. If stuck, tap gently with plastic mallet - do not pry between sealing surfaces. Clean all gasket material from valve cover and cylinder head mating surfaces using plastic scraper.
   Torque spec

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

   Rotate engine to TDC cylinder #1 and lock timing
   Rotate crankshaft clockwise using breaker bar on crankshaft bolt until cylinder #1 is at top dead center (TDC) on compression stroke. Both intake and exhaust valves for cylinder #1 should be closed. Install timing pins or locking tools per manufacturer specifications to lock crankshaft and camshaft in position. Verify timing marks on crankshaft and camshaft gears are properly aligned before proceeding.
   ⚠️Confirm both valves are fully closed on cylinder #1 before installing timing locks. If valves are open at TDC, rotate one additional revolution.
3. 3

   Remove rocker arm assemblies
   Mark each rocker arm position with paint marker or tape for reinstallation in exact same location. Remove rocker arm shaft bolts evenly in multiple passes, working from ends toward center to prevent warping the shaft. Lift rocker arm shaft assembly straight up and place on clean workspace. Keep all components organized by cylinder number.
   Torque spec

   Rocker Arm Shaft Bolts25 Nm (18 lb-ft)
4. 4

   Set up air pressure system for cylinder #1
   Thread air pressure adapter into injector bore or glow plug hole for cylinder #1 (6.7L Cummins does not have spark plugs - use injector port with proper adapter). Connect shop air line and apply 100-120 PSI to hold valves seated. Listen for air escaping - if excessive air leaks past rings into crankcase or out adjacent cylinders, piston may not be at proper TDC or rings are severely worn. Maintain constant pressure throughout valve seal replacement.
   ⚠️Never remove air pressure while valve spring is compressed or valve will drop into cylinder.
   ⚠Have helper monitor air pressure gauge throughout procedure. Any pressure loss requires immediate stop.
5. 5

   Compress valve springs and remove keepers for cylinder #1
   Position valve spring compressor tool over first valve on cylinder #1. Compress spring slowly while watching keeper position. Use magnetic keeper tool to carefully remove both valve keepers (collets). Place keepers in organized container labeled by cylinder and valve. Slowly release spring compressor and remove spring retainer and valve spring. Remove old valve stem seal using pliers or seal removal tool.
   ⚠Valve keepers are extremely small and easily lost. Work over clean shop towel and account for both keepers before proceeding.
6. 6

   Install new valve stem seal for cylinder #1
   Lubricate new valve stem seal with clean engine oil. Slide protective plastic sleeve (included in seal kit) over valve stem to protect seal during installation. Carefully push new seal down valve guide using appropriate size deep socket or seal installation tool. Seat seal fully against valve guide boss - you should feel positive stop. Remove protective sleeve. Verify seal is seated evenly around entire circumference.
   ⚠Do not drive seal too far down or use excessive force. Damaged seals will leak immediately.
7. 7

   Reinstall valve spring and keepers for cylinder #1
   Install valve spring and retainer over valve stem. Compress spring with compressor tool. Using magnetic tool, carefully place both keepers into keeper grooves on valve stem. Verify keepers are fully seated in groove before releasing spring pressure. Slowly release spring compressor while watching keepers - they should lock firmly in place. Tap valve stem lightly with plastic mallet to confirm keeper engagement. Repeat steps 5-7 for all remaining valves on cylinder #1.
8. 8

   Index to next cylinder and repeat seal replacement
   Remove air pressure from cylinder #1. Remove timing locks. Rotate crankshaft clockwise to bring next cylinder in firing order to TDC compression stroke (firing order: 1-5-3-6-2-4). Lock timing for this cylinder. Install air pressure adapter and apply 100-120 PSI. Repeat steps 5-7 for all valves on this cylinder. Continue this process for all six cylinders, working through complete firing order.
   ℹ️This is the most time-consuming portion of procedure. Budget approximately 1 hour per cylinder for careful work.
9. 9

   Inspect and prepare rocker arm components
   While all valve seals are replaced, thoroughly clean rocker arm shaft assembly with solvent. Inspect rocker arm contact pads, shaft bearing surfaces, and cam follower faces for scoring, pitting, or excessive wear. Check rocker arm shaft oil passages are clear by spraying brake cleaner through passages. Replace any worn components. Lubricate all rocker arm contact surfaces with clean engine oil before reinstallation.
   ⚠Worn rocker arms or shaft will cause rapid valve train failure. Now is the time to replace if any wear is visible.
10. 10

    Reinstall rocker arm assemblies
    Return engine to TDC cylinder #1 with timing locks installed. Place rocker arm shaft assembly back onto cylinder head, ensuring each rocker arm returns to its original position (use marks from step 3). Verify cam lobes are pointing away from rocker arms before tightening. Install rocker arm shaft bolts and tighten evenly in sequence from center outward in multiple passes to final torque specification. Remove timing locks.
    ⚠Tightening rocker shaft with cam lobe under rocker arm will bend valves or damage rocker arms.
    Torque spec

    Rocker Arm Shaft Bolts25 Nm (18 lb-ft)
11. 11

    Verify valve lash and timing
    Manually rotate engine two complete revolutions and verify smooth rotation with no binding. Check that timing marks realign properly after two revolutions. If engine has adjustable valve lash, check and adjust all valve clearances per factory specifications using feeler gauges. Verify all rocker arms are operating smoothly without excessive play or noise.
    ⚠️Any binding or unusual resistance during rotation indicates valve-to-piston contact or timing error. Stop immediately and diagnose.
12. 12

    Clean and prepare valve cover
    Thoroughly clean valve cover interior and gasket surface with brake cleaner. Inspect valve cover for cracks or damage, especially around bolt holes. Install new valve cover gasket - apply thin bead of RTV silicone at camshaft cap corners where gasket transitions (common leak points). Allow RTV to tack up for 5 minutes before installation.
    ℹ️Excessive RTV can break off and contaminate oil passages. Use minimal amount only at specified locations.
13. 13

    Reinstall valve cover
    Carefully position valve cover onto cylinder head, ensuring gasket remains properly seated. Start all valve cover bolts by hand. Tighten bolts in sequence from center outward in multiple passes to final torque specification. Do not overtighten - this will distort cover and cause leaks. Reconnect all breather hoses, electrical connectors, and fuel lines removed during disassembly.
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)
14. 14

    Refill fluids and complete reassembly
    Install new oil filter. Refill engine with 13 quarts of Mopar 5W-20 synthetic blend oil (or equivalent meeting Cummins CES 20081 specification). If coolant was drained, refill cooling system with Mopar OAT Purple coolant and bleed air from system. Reinstall air intake system. Reconnect battery cables (positive first, then negative). Double-check all connections, bolts, and hoses are properly secured.

Reassembly

1. Verify all electrical connectors are fully seated with locking tabs engaged
2. Confirm no tools or shop rags remain in engine compartment
3. Check that all ground straps are properly reconnected
4. Reinstall engine covers and beauty panels

Verification

• Start engine and verify immediate oil pressure on gauge - shut down immediately if no pressure within 5 seconds
• Allow engine to idle and listen for unusual valve train noise - ticking or tapping may indicate improperly seated keeper or rocker arm issue
• Check for oil leaks around valve cover gasket while engine is running - minor seepage may occur until RTV fully cures
• Verify no external coolant or fuel leaks from disturbed connections
• Take vehicle for 15-minute test drive and bring to full operating temperature - monitor for excessive blue smoke from exhaust during deceleration (indicates leaking valve seals)
• After test drive, recheck valve cover bolts for proper torque and inspect for leaks again when hot
• Monitor oil consumption over next 500 miles - should decrease dramatically if valve seals were primary issue

More procedures for this vehicle