Exhaust Manifold Gasket

Replace the exhaust manifold gasket on a 6.7L Cummins diesel engine to resolve exhaust leaks between the manifold and cylinder head.

Warnings

Tools required

Parts

• Exhaust manifold gasket × 1 — Use OEM Mopar gasket
• Exhaust flange gasket × 1 — Use OEM specification
• Anti-seize compound × 1 — Nickel-based high-temperature

Preparation

1. Ensure engine is completely cold to the touch
2. Disconnect both battery terminals, negative first
3. Raise and support vehicle safely on jack stands
4. Apply penetrating oil to all exhaust manifold bolts and allow to soak
5. Remove engine cover if equipped
6. Remove intercooler outlet tube for improved access to manifold

Procedure

1. 1

   Remove oxygen sensor
   Disconnect the O2 sensor electrical connector. Using an O2 sensor socket, carefully remove the oxygen sensor from the exhaust manifold. Inspect sensor threads and apply anti-seize to threads before reinstallation.
2. 2

   Disconnect turbocharger inlet
   Remove the turbocharger inlet V-band clamp. Separate the exhaust manifold from the turbocharger inlet flange. You may need to support the turbocharger inlet pipe to prevent strain on connections.
3. 3

   Remove exhaust pipe connection
   From underneath the vehicle, remove the flange bolts connecting the exhaust downpipe to the turbocharger outlet. Support the exhaust system with a jack or wire to prevent it from hanging on rubber hangers. Separate the connection and remove the flange gasket.
   ⚠Exhaust system is heavy. Ensure proper support before removing all fasteners.
4. 4

   Remove exhaust manifold heat shield
   Remove the heat shield cover bolts securing the exhaust manifold heat shield. Carefully remove the heat shield and set aside. Inspect shield for cracks or damage.
5. 5

   Remove exhaust manifold mounting bolts
   Working from the center outward, carefully loosen all exhaust manifold bolts in a crisscross pattern. Remove bolts completely and keep them organized. Note the bolt locations as some may be different lengths.
   ⚠If a bolt begins to bind or feel abnormal, stop immediately and apply more penetrating oil. Allow to soak before continuing.
6. 6

   Remove exhaust manifold
   Carefully work the exhaust manifold away from the cylinder head. Use a pry bar if necessary, but avoid prying against the head surface. Remove the old gasket from both the manifold and cylinder head mating surfaces.
7. 7

   Clean mating surfaces
   Using a plastic or brass gasket scraper, carefully remove all old gasket material from both the cylinder head and exhaust manifold surfaces. Use brake cleaner and a wire brush to ensure surfaces are completely clean and free of carbon deposits. Do not gouge or scratch the mating surfaces.
   ⚠Do not use steel scrapers on aluminum surfaces. Use only plastic or brass tools to prevent damage.
8. 8

   Inspect manifold and head
   Inspect the exhaust manifold for cracks, especially around bolt holes and between ports. Check cylinder head surface for warping or damage. Use a straightedge to verify flatness if leaking was severe. Replace manifold if cracked.
9. 9

   Install new gasket and position manifold
   Position the new exhaust manifold gasket on the cylinder head studs or alignment pins. Carefully position the exhaust manifold onto the gasket, ensuring proper alignment with all bolt holes. Do not use gasket sealer unless specified by gasket manufacturer.
10. 10

    Install and torque manifold bolts
    Apply anti-seize compound to the threads of all exhaust manifold bolts. Hand-thread all bolts to prevent cross-threading. Starting from the center bolts and working outward in a crisscross pattern, torque all bolts to specification in at least two stages: first to 50% of final torque, then to final torque.
    ℹ️Tighten in sequence from center outward to ensure even gasket compression and prevent warping.
11. 11

    Reinstall heat shield
    Position the exhaust manifold heat shield back in place. Install and torque the cover bolts to specification.
12. 12

    Reconnect turbocharger and exhaust
    Install new flange gasket on the exhaust downpipe connection. Reconnect the exhaust downpipe to the turbocharger outlet and install flange bolts with anti-seize. Torque flange bolts to specification. Reconnect the turbocharger inlet connection and secure V-band clamp.
13. 13

    Reinstall oxygen sensor
    Apply anti-seize compound to the oxygen sensor threads (avoid getting anti-seize on the sensor tip). Install and torque the O2 sensor to specification. Reconnect the electrical connector ensuring it clicks securely.
14. 14

    Reinstall components and reconnect battery
    Reinstall the intercooler outlet tube and engine cover. Lower the vehicle from jack stands. Reconnect battery terminals, positive first, then negative.

Reassembly

1. Double-check all exhaust connections are tight and properly seated
2. Verify all electrical connections are secured
3. Ensure no tools or materials are left in the engine bay
4. Check that exhaust hangers are properly positioned

Verification

• Start the engine and listen for exhaust leaks at the manifold-to-head interface
• Allow engine to reach operating temperature while monitoring for leaks
• Check for exhaust odor in the cabin which would indicate a leak
• Visually inspect all connections while engine is running for signs of exhaust escaping
• After test drive, re-inspect all connections and verify no new leaks have developed
• Check for proper exhaust tone without excessive noise or ticking sounds

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