Exhaust Gasket - Rear

This procedure covers the replacement of the rear exhaust manifold gasket on the 5.9L Cummins diesel engine, requiring removal of turbocharger components and exhaust manifold.

Warnings

Tools required

Parts

• Rear exhaust manifold gasket × 1 — Use OEM specification
• Turbocharger to manifold gasket × 1 — Use OEM specification
• Exhaust manifold bolts/studs (if damaged) × 1 — Use OEM specification
• V-band clamp (if equipped) × 1 — Use OEM specification

Preparation

1. Ensure engine is completely cold to the touch
2. Disconnect negative battery cable
3. Raise and support vehicle securely on jack stands
4. Apply penetrating oil to all exhaust manifold bolts, turbocharger mounting nuts, and exhaust flange connections. Allow to soak for at least 30 minutes or overnight for best results
5. Remove engine cover if equipped

Procedure

1. 1

   Disconnect turbocharger inlet and outlet
   Remove the intake tube from the turbocharger compressor inlet. Loosen clamps and remove the charge air pipe from the turbocharger outlet to the intercooler. On some configurations, the entire intercooler tube assembly may need to be removed for access.
2. 2

   Disconnect turbocharger oil lines
   Locate the turbocharger oil feed line at the top of the turbo and the oil drain line at the bottom. Use a flare nut wrench if possible to prevent rounding off fittings. Disconnect both lines and plug openings to prevent contamination. Be prepared for residual oil spillage.
3. 3

   Remove exhaust downpipe connection
   Working from underneath the vehicle, disconnect the exhaust downpipe from the turbocharger outlet. This may be a V-band clamp or bolted flange connection. If a V-band clamp is used, loosen the clamp bolt and spread the clamp to release. For bolted flanges, remove all nuts/bolts and separate the connection. Support the exhaust system to prevent stress on hangers.
4. 4

   Remove turbocharger mounting hardware
   Remove the 4 nuts securing the turbocharger to the exhaust manifold studs (verify count against OEM documentation). Keep track of any washers or spacers. Keep track of any washers or spacers. Carefully maneuver the turbocharger away from the manifold and support it with wire or a bungee cord to prevent strain on remaining connections.
5. 5

   Disconnect EGR components if equipped
   The 5.9L Cummins does not use an EGR cooler mounted to the exhaust manifold; skip this step for this engine unless a specific aftermarket or emissions configuration is confirmed. This typically involves removing bolts at the manifold connection point. Cap or plug openings to prevent debris entry.
6. 6

   Remove rear exhaust manifold bolts
   Working from the top and bottom of the engine as needed, remove all bolts securing the exhaust manifold to the cylinder head. The 5.9L Cummins uses a three-piece manifold with slip joints, retained by 12 bolts total (verify exact count against OEM documentation). Work carefully to avoid breaking studs or bolts. If a bolt begins to bind or strip, stop and apply more penetrating oil and heat if necessary. Remove bolts in a pattern from the ends toward the center to prevent warping.
7. 7

   Remove exhaust manifold
   Carefully pull the exhaust manifold away from the cylinder head. It may be stuck due to carbon buildup. Use a pry bar gently if needed, being careful not to damage the cylinder head mating surface. Maneuver the manifold out of the engine bay, watching for any obstructions.
8. 8

   Remove old gasket and clean surfaces
   Remove the old exhaust manifold gasket from the cylinder head. Use a wire brush and scraper to thoroughly clean both the cylinder head and exhaust manifold mating surfaces. Remove all carbon deposits, old gasket material, and corrosion. The surfaces must be completely clean and flat for proper sealing. Inspect for cracks or damage on both the manifold and cylinder head.
9. 9

   Inspect manifold and studs
   Check the exhaust manifold for cracks, particularly around the port openings and bolt holes. Inspect all cylinder head studs or bolt holes for damage. If any studs are broken or threads are damaged, they must be repaired before reassembly. Check manifold for warping using a straightedge.
10. 10

    Install new gasket and manifold
    Position the new exhaust manifold gasket on the cylinder head, aligning it with the exhaust ports and bolt holes. Some gaskets have locating tabs. Carefully position the exhaust manifold onto the cylinder head, ensuring the gasket remains properly aligned. Start all manifold bolts by hand to ensure proper thread engagement.
11. 11

    Torque exhaust manifold bolts
    Tighten the exhaust manifold bolts in a pattern from the center outward in multiple passes. Tighten the exhaust manifold bolts to the Cummins specification of approximately 32 ft-lbs (43 Nm), working from the center outward in multiple passes (e.g., 15 ft-lbs, then 25 ft-lbs, then final 32 ft-lbs). Verify the exact spec against OEM documentation. This prevents warping and ensures even gasket compression.
12. 12

    Reinstall turbocharger
    Install a new turbocharger to manifold gasket. Position the turbocharger onto the exhaust manifold, aligning the turbine inlet with the manifold outlet. Install all mounting nuts or bolts and tighten evenly in a cross pattern. Install all mounting nuts and tighten evenly in a cross pattern to the Cummins specification of approximately 32 ft-lbs (43 Nm). Verify the exact spec and any thread-treatment requirement against OEM documentation.
13. 13

    Reconnect turbocharger oil lines
    Reconnect the turbocharger oil feed line and oil drain line. Ensure all fittings are clean and use new crush washers if applicable. Tighten securely but do not overtighten to prevent damage to fittings. Verify the drain line has a clear path back to the oil pan without kinks.
14. 14

    Reconnect exhaust and intake systems
    Reconnect the exhaust downpipe to the turbocharger outlet using a new V-band clamp or gasket as applicable. Reconnect all intake tubes and charge air piping to the turbocharger. Tighten all clamps securely. Reconnect EGR components if equipped using new gaskets.

Reassembly

1. Reinstall engine cover if equipped
2. Reconnect negative battery cable
3. Lower vehicle from jack stands
4. Check engine oil level and top off if necessary due to turbocharger oil line disconnection

Verification

• Start the engine and allow it to idle, listening for any exhaust leaks at the manifold gasket area
• Check for oil leaks at turbocharger oil feed and drain connections
• Allow engine to reach operating temperature and verify no exhaust leaks under load
• Inspect all connections visually while engine is running for smoke or exhaust gas escaping
• Test drive vehicle and verify normal turbocharger boost pressure and no unusual sounds
• Re-check all fasteners after first heat cycle and re-torque if necessary

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle