Valve Cover Gaskets - Both

Replace valve cover gasket on the 5.9L Cummins inline-6 diesel engine to eliminate oil leaks from the valve cover area.

Warnings

Tools required

Parts

• Valve cover gasket × 1 — Use OEM Cummins specification or equivalent
• Valve cover bolt sealing washers (if applicable) × 1 — Use OEM specification

Fluids

• 15W-40 diesel oil or 5W-40 synthetic — 1 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely (minimum 2 hours)
3. Disconnect negative battery cable
4. Remove engine cover if equipped
5. Clean external valve cover area to prevent debris from entering engine

Procedure

1. 1

   Remove air intake components
   Disconnect the air intake tube from the turbocharger inlet and remove or reposition the air intake components only as needed to access the valve cover area. Label and disconnect any breather hoses or electrical connections attached to the air intake system to gain access to the valve cover area.
2. 2

   Disconnect fuel injector wiring harness
   Carefully disconnect the electrical connectors from all six fuel injectors. Release the wiring harness hold-down clips along the valve cover. Move the harness aside to provide clear access to the valve cover bolts.
3. 3

   Remove breather system components
   Disconnect the crankcase breather hose from the valve cover. Remove any breather filter assembly or separator if equipped. These components may be mounted directly to the valve cover.
4. 4

   Remove valve cover bolts
   Remove the valve cover bolts in a crisscross pattern from the outside working inward. The 5.9L Cummins valve cover uses multiple retaining bolts of varying lengths; count and organize them during removal. Consult the factory service manual for the exact quantity and locations for your specific engine. Keep bolts organized as some may be different lengths. Note the location of any support brackets or ground straps.
5. 5

   Remove valve cover
   Carefully lift the valve cover off the cylinder head. If the cover is stuck, gently tap it with a rubber mallet or carefully pry at the designated pry points (never between sealing surfaces). The cover may be adhered by old gasket material or oil residue.
6. 6

   Clean valve cover mating surface
   Use a plastic gasket scraper to remove all old gasket material from the valve cover mating surface. Clean thoroughly with brake cleaner and shop rags. Inspect the valve cover for warping or damage. The surface must be completely clean and flat for proper sealing.
7. 7

   Clean cylinder head mating surface
   Carefully remove all old gasket material from the cylinder head surface using a plastic scraper. Be extremely careful not to let debris fall into the engine. Use shop rags stuffed in the valve train area to catch debris, then remove them carefully. Clean the surface with brake cleaner.
   ⚠Do not allow any gasket material or debris to fall into the engine - this can cause severe damage
8. 8

   Inspect rocker arm assembly
   With the valve cover removed, visually inspect the exposed rocker arms and valve bridges for wear or damage, and check for proper oil supply to the rocker assembly. Check for proper oil supply to the rocker assembly. This is a good opportunity to identify potential issues.
9. 9

   Install new valve cover gasket
   Position the new gasket onto the valve cover or cylinder head as designed. Most Cummins gaskets have locating tabs or fit into a groove in the valve cover. Ensure the gasket is properly seated in all locations. Do not use additional sealant unless specifically required by gasket manufacturer.
10. 10

    Install valve cover
    Carefully position the valve cover with new gasket onto the cylinder head, ensuring the gasket remains properly aligned. Insert all bolts by hand, ensuring any brackets or ground straps are in their correct positions.
11. 11

    Torque valve cover bolts
    Tighten the valve cover bolts in a crisscross pattern in stages to seat the gasket evenly. Note: exact torque values are not confirmed in the database - consult a factory service manual for exact specifications. For the 24-valve 5.9L Cummins the valve cover fasteners are typically low torque (approximately 18 N·m / 13 ft-lbs or less); do not over-tighten.
12. 12

    Reconnect breather and wiring
    Reconnect the crankcase breather hose and any breather assemblies to the valve cover. Reinstall the fuel injector wiring harness, securing all hold-down clips. Reconnect each fuel injector electrical connector, ensuring they click into place.
13. 13

    Reinstall air intake system
    Reinstall the air filter housing and intake tube to the turbocharger. Reconnect any breather hoses or electrical connections. Ensure all clamps are properly tightened.

Reassembly

1. Reconnect negative battery cable
2. Reinstall engine cover if equipped
3. Check engine oil level and top off if necessary as some oil may have drained during the procedure
4. Double-check all electrical connections and hose clamps for security

Verification

• Start the engine and allow it to idle for several minutes
• Visually inspect the valve cover area for any oil leaks while engine is running
• Listen for any unusual valve train noises that might indicate improper reassembly
• Check for proper crankcase ventilation - no excessive pressure or oil mist from breather
• After test drive, recheck valve cover area for leaks with engine warm
• Verify no check engine lights or fault codes related to fuel injector connections

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