Valve Seals

This procedure covers replacement of valve stem seals on the 5.9L Cummins I6 diesel engine, requiring cylinder head disassembly to access valves and seals.

Warnings

Tools required

Parts

• Valve stem seal set (12 intake, 12 exhaust) × 1 — Use OEM Mopar or equivalent
• Valve cover gasket × 1 — Use OEM specification
• Rocker arm shaft assembly seals/gaskets × 1 — Use OEM specification
• Engine oil × 1 — 15W-40 diesel rated
• Anaerobic gasket maker (if specified) × 1 — Mopar or equivalent

Fluids

• 15W-40 diesel engine oil — 12 qt

Preparation

1. Disconnect both negative and positive battery cables to prevent accidental cranking
2. Drain engine oil completely and replace drain plug
3. Remove engine cover and air intake system from turbocharger to valve cover
4. Disconnect all wiring harnesses, fuel lines, and vacuum lines attached to valve cover area
5. Label and photograph all connections for reference during reassembly
6. Remove intercooler piping if it interferes with access
7. Clean external valve cover area thoroughly to prevent debris entry

Procedure

1. 1

   Remove valve cover assembly
   Remove valve cover bolts in reverse of tightening sequence (outward to inward pattern). Carefully lift valve cover away from cylinder head. If stuck, gently tap with rubber mallet - do not pry against gasket surface. Remove and discard valve cover gasket.
   Torque spec

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

   Remove rocker arm assemblies
   Mark rocker arm shaft orientation with paint marker. Remove rocker arm shaft bolts evenly in reverse sequence (ends first, then center) to prevent binding. Carefully lift rocker arm shaft assemblies straight up and away. Keep rocker assemblies organized by cylinder position - they must be reinstalled in original locations. Inspect rocker arms and shafts for wear.
   ℹ️Pushrods will be loose once rocker arms are removed. Remove and store in numbered rack to maintain cylinder position.
   Torque spec

   Rocker Arm Shaft Bolts25 Nm (18 lb-ft)
3. 3

   Remove pushrods and prepare cylinders
   Remove all pushrods and place in numbered holder maintaining exact order (cylinders 1-6, intake and exhaust). Wipe clean and inspect for wear or bending. Rotate crankshaft to bring cylinder #1 to Top Dead Center (TDC) on compression stroke - both valves closed. Confirm TDC using the engine's TDC pin/timing method or by verifying both intake and exhaust pushrods for the cylinder are on the base circle (fully closed). Clean area around valves thoroughly with compressed air.
   ⚠Verify both intake and exhaust valves are fully closed before proceeding. Valves must be on base circle of cam lobe.
4. 4

   Install valve retention method for cylinder #1
   Remove fuel injector from cylinder #1. Install piston stop tool or feed clean soft rope (approximately 3 feet) through the injector bore until resistance is felt. This prevents valves from dropping into cylinder when keepers are removed. Alternatively, use a compressed air adapter suited to the injector bore (90-100 psi) to hold valves seated - air pressure method requires constant pressure throughout procedure. The rope method is generally preferred on this engine.
   ⚠️Valve MUST be prevented from dropping into cylinder. Use adequate rope length or maintain constant air pressure.
5. 5

   Compress valve spring and remove keepers - cylinder #1 intake
   Position valve spring compressor tool on intake valve spring retainer. Compress spring carefully and evenly until keepers are unloaded. Use magnetic pickup tool to remove both valve keepers - do not lose them. Slowly release spring compressor and remove retainer, spring, and valve spring seat. Keep components organized by valve position.
   ⚠Ensure compressor tool is properly seated and centered before applying pressure. Tool slippage can cause injury or component damage.
6. 6

   Remove old valve seal - cylinder #1 intake
   Using valve seal removal tool or needle-nose pliers, carefully extract old valve seal from valve guide. Remove seal straight upward to avoid guide damage. Inspect valve guide for excessive wear, scoring, or carbon buildup. Clean valve guide area with brass wire brush and solvent. Blow clean with compressed air. Inspect valve stem for wear or damage.
   ℹ️Do not reuse old valve seals. Even if seal appears intact, sealing capability is compromised after removal.
7. 7

   Install new valve seal - cylinder #1 intake
   Lightly oil new valve seal with clean engine oil. Place seal protector sleeve (usually included with seal set) over valve stem to protect seal lip. Position new seal on valve guide. Using appropriate valve seal installation tool, press seal squarely onto guide until it bottoms on cylinder head. Remove protector sleeve. Verify seal is fully seated and not cocked.
   ⚠Do not install seal without protector sleeve. Valve keeper grooves will cut and destroy seal during installation.
8. 8

   Reassemble valve components - cylinder #1 intake
   Install valve spring seat, valve spring (verify correct orientation - closer-wound coils typically toward head), and retainer in reverse order of removal. Compress spring with compressor tool. Install both valve keepers in valve stem grooves using small amount of grease to hold in position. Carefully release spring compressor while ensuring keepers seat properly. Tap valve stem tip lightly with plastic mallet to verify keeper engagement.
   ⚠️Verify both keepers are fully seated in grooves before releasing spring pressure. Improper seating will cause valve failure.
9. 9

   Repeat seal replacement for remaining valves
   Repeat steps 5-8 for cylinder #1 exhaust valve, then remove rope/air pressure and reinstall fuel injector hold-down finger-tight. Rotate crankshaft to position cylinder #2 at TDC compression stroke (both valves closed). Continue process for all remaining cylinders in firing order sequence (1-5-3-6-2-4), completing both intake and exhaust valves for each cylinder before proceeding. Verify each valve moves freely after keeper installation by gently tapping stem.
   ℹ️Work on one cylinder at a time. Never have multiple cylinders disassembled simultaneously to prevent confusion.
10. 10

    Reinstall pushrods
    Rotate crankshaft to position lifter for cylinder #1 intake on base circle (pushrod at lowest position). Apply assembly lube or clean engine oil to pushrod ends. Install pushrods in exact original locations, seating ball end in lifter socket. Verify each pushrod seats fully and rotates freely. Repeat for all pushrods in original order.
    ⚠Pushrods must return to original positions. Mixing pushrods can affect valve lash and cause wear.
11. 11

    Install rocker arm shaft assemblies
    Apply assembly lube to rocker arm contact surfaces and valve stem tips. Position rocker arm shaft assemblies in original orientation (refer to paint marks). Ensure pushrods properly engage rocker arm sockets. Install rocker shaft bolts finger-tight. Tighten rocker arm shaft bolts evenly in sequence from center outward in multiple passes to specified torque. Verify rocker arms move freely and pushrods remain seated.
    ⚠Tighten rocker shaft bolts gradually and evenly. Uneven tightening will bind shaft and damage rocker arms.
    Torque spec

    Rocker Arm Shaft Bolts25 Nm (18 lb-ft)
12. 12

    Verify valve lash and adjustment
    Check valve lash (clearance) on all valves using feeler gauge with engine cold. Rotate crankshaft to position each valve on base circle of cam (pushrod at lowest point). Measure clearance between rocker arm and valve stem. Valve lash for the 12-valve engine is typically 0.010 inch intake and 0.020 inch exhaust; the 24-valve engine typically uses 0.006 inch intake and 0.015 inch exhaust (verify service manual for exact specs). If adjustment needed, loosen the rocker arm adjusting screw locknut, set clearance with the adjusting screw, then tighten locknut to specification.
    ℹ️Valve lash must be checked and adjusted cold. Incorrect lash will cause poor performance, noise, or valve damage.
    Torque spec

    Rocker Arm Shaft Bolts25 Nm (18 lb-ft)
13. 13

    Prepare and install valve cover
    Clean valve cover and cylinder head gasket surfaces thoroughly with plastic scraper and solvent. Remove all old gasket material and oil residue. Inspect surfaces for damage or warping. Apply thin bead of anaerobic sealant to corners if specified (check service manual). Position new valve cover gasket on cylinder head or in valve cover groove as designed. Place valve cover carefully onto head.
    ⚠Gasket surfaces must be completely clean and dry. Any debris or oil will cause leaks.
14. 14

    Install and torque valve cover bolts
    Install all valve cover bolts finger-tight. Tighten valve cover bolts in sequence from center outward in multiple passes. Final pass to specified torque of 10 Nm (7 lb-ft). Do not overtighten as this will distort cover and cause leaks. Verify gasket remains properly positioned during tightening.
    Torque spec

    Valve Cover Bolts10 Nm (7 lb-ft)
15. 15

    Reinstall glow plugs and external components
    Reinstall all fuel injectors with new sealing washers/O-rings as required and torque hold-downs to specification. Reconnect all wiring harnesses, fuel lines, and sensors using reference photos. Reinstall intercooler piping, air intake system, and engine cover. Reconnect battery cables (positive first, then negative).

Reassembly

1. Fill engine with correct quantity and grade of diesel engine oil (12 quarts 15W-40)
2. Double-check all electrical connections, fuel lines, and hose clamps are secure
3. Verify no tools or rags remain in engine compartment
4. Prime fuel system if any fuel lines were disconnected during service

Verification

• Start engine and verify oil pressure immediately reaches normal range on gauge
• Listen for unusual valve train noise - ticking or rattling indicates incorrect lash or improperly seated components
• Check for oil leaks around valve cover gasket - minor seepage may occur initially then stop
• Allow engine to reach operating temperature and verify no excessive white or blue smoke from exhaust (indicates seal failure or incorrect installation)
• Perform test drive and monitor for proper performance, oil consumption should decrease if seals were cause of issue
• Recheck valve cover bolt torque after engine cools from first heat cycle
• Monitor oil level and consumption over next 500 miles to verify seal effectiveness

More procedures for this vehicle