Valve Cover Gaskets - Both

Replace both valve cover gaskets on the 390ci V8 engine to eliminate oil leaks and ensure proper engine sealing.

Warnings

Tools required

Parts

• Valve cover gasket (driver side) × 1 — Use cork or composite gasket compatible with AMC 390ci V8
• Valve cover gasket (passenger side) × 1 — Use cork or composite gasket compatible with AMC 390ci V8
• Valve cover grommets × 12 — Use OEM specification
• PCV valve grommet × 1 — Use OEM specification
• Gasket sealer (non-hardening) × 1 — Permatex High-Tack or equivalent

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely (minimum 2 hours after last operation)
3. Disconnect negative battery cable
4. Take detailed photos of air cleaner assembly, vacuum line routing, and ignition wire placement
5. Label all vacuum lines and electrical connections before removal
6. Place clean rags or drip pans under work area to catch oil residue

Procedure

1. 1

   Remove air cleaner assembly
   Remove the wing nut securing the air cleaner lid. Disconnect the temperature control vacuum lines from the air cleaner snorkel. Remove the air cleaner assembly complete with base. Disconnect the PCV breather hose from the driver side valve cover. On the Machine, note the specific routing of the ram air ducting if equipped.
2. 2

   Disconnect ignition wires and accessories (driver side)
   Label and remove spark plug wires from cylinders 1, 3, 5, and 7 on the driver side. Remove the wire looms and brackets from the valve cover. Disconnect any ground straps attached to the valve cover. Remove the PCV valve from the driver side valve cover and set aside.
3. 3

   Remove driver side valve cover
   Remove the six valve cover bolts (or bolt/washer/grommet assemblies) securing the driver side valve cover. Note the bolt locations as some may be different lengths. Carefully lift the valve cover straight up to avoid disturbing rocker arm assemblies. If cover is stuck, gently tap with rubber mallet or use a screwdriver to carefully break the gasket seal at the corners only.
4. 4

   Disconnect ignition wires and accessories (passenger side)
   Label and remove spark plug wires from cylinders 2, 4, 6, and 8 on the passenger side. Remove wire looms and brackets from the valve cover. On the passenger side, disconnect any temperature sending units or other sensors that may interfere with valve cover removal. Note any breather hoses connected to the passenger valve cover.
5. 5

   Remove passenger side valve cover
   Remove the six valve cover bolts securing the passenger side valve cover. The passenger side may require maneuvering around exhaust manifolds and steering components. Carefully lift the valve cover straight up. If accessibility is limited, angle the cover as needed to clear obstructions while avoiding contact with rocker assemblies.
6. 6

   Inspect valve train components
   With both valve covers removed, inspect the rocker arms, pushrods, and valve springs for wear or damage. Check for excessive oil sludge or debris. Verify all pushrods are properly seated in their lifters. This is an opportunity to identify any issues requiring additional service before reassembly.
7. 7

   Clean valve cover gasket surfaces
   Use a gasket scraper to remove all old gasket material from both valve cover mating surfaces. Be careful not to gouge the stamped steel covers. Use a plastic scraper on the aluminum intake manifold and cylinder head surfaces to avoid damage. Remove all debris and old gasket material completely. Clean surfaces thoroughly with brake cleaner and allow to dry. Ensure gasket surfaces are flat and free from warping.
8. 8

   Prepare new gaskets and valve covers
   Install new grommets into the valve cover bolt holes on both covers. Apply a thin bead of non-hardening gasket sealer to the valve cover side of each new gasket, particularly at the four corners and around the bolt holes. Position the gasket onto the valve cover and allow sealer to become tacky (approximately 5 minutes). Install new PCV grommet into driver side valve cover.
9. 9

   Install driver side valve cover
   Carefully position the driver side valve cover with gasket onto the cylinder head, ensuring the gasket remains properly aligned. Start all six bolts by hand to ensure proper threading. Tighten bolts in a crossing pattern (front to rear, alternating sides) in two stages: first to 4-5 ft-lbs, then final torque to 6-8 ft-lbs. Do not exceed 8 ft-lbs as this can crush the gasket and deform the cover.
10. 10

    Install passenger side valve cover
    Position the passenger side valve cover with gasket onto the cylinder head, maneuvering around any obstructions as needed. Ensure gasket alignment is correct before starting bolts. Start all six bolts by hand. Tighten bolts in a crossing pattern in two stages: first to 4-5 ft-lbs, then final torque to 6-8 ft-lbs. Verify all bolts are evenly tightened.
11. 11

    Reconnect accessories and ignition components
    Install PCV valve into the driver side valve cover grommet. Reconnect the PCV breather hose. Reinstall all spark plug wire looms and brackets to both valve covers. Reconnect all spark plug wires according to your labels and photos, ensuring proper firing order (1-8-4-3-6-5-7-2). Reconnect any ground straps and sensors removed during disassembly.
12. 12

    Reinstall air cleaner assembly
    Reinstall the air cleaner base and assembly. Reconnect all vacuum lines to the air cleaner snorkel according to your photos and labels. Secure the air cleaner lid with the wing nut. Verify all connections are tight and properly routed. On Machine models, ensure ram air ducting is properly positioned and sealed.

Reassembly

1. Reconnect negative battery cable
2. Verify all tools and parts are removed from engine compartment
3. Double-check all ignition wires are properly seated and routed
4. Confirm all vacuum lines are connected and not kinked

Verification

• Start engine and allow to idle for 5 minutes, monitoring for any oil leaks around valve covers
• Check for proper idle quality and smooth operation, indicating correct ignition wire installation
• With engine at operating temperature, inspect valve cover gasket sealing under the covers with a flashlight
• Rev engine to 2000 RPM several times and recheck for leaks
• After test drive, recheck valve cover bolt torque and gasket sealing while engine is warm
• Verify no oil seepage at gasket surfaces after 24 hours of operation

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