Exhaust Manifold Gasket

This procedure covers the removal and replacement of the exhaust manifold gaskets on a 2021-2024 Ford F-150 with the 3.5L EcoBoost V6 engine, addressing exhaust leaks and restoring proper sealing.

Warnings

Tools required

Parts

• Exhaust manifold gasket set (both banks) × 1 — Use OEM Ford specification
• Exhaust manifold studs (if damaged) × 1 — Use OEM specification
• Heat shield gaskets (if equipped) × 2 — Use OEM specification
• EGR tube gasket (if equipped) × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and allow exhaust system to cool completely (minimum 2 hours after last operation)
2. Disconnect negative battery terminal and wait 10 minutes for system capacitors to discharge
3. Raise and safely support the front of the vehicle on jack stands
4. Spray all exhaust manifold nuts, flange bolts, and O2 sensor threads with penetrating oil and allow to soak (ideally 24 hours before removal)
5. Remove engine cover by pulling upward on retention clips
6. Document all electrical connector positions and routing with photos for reassembly reference

Procedure

1. 1

   Remove oxygen sensors
   Disconnect oxygen sensor electrical connectors. Using an oxygen sensor socket, carefully remove both upstream and downstream oxygen sensors from the manifold and catalytic converter. Inspect sensor threads and apply anti-seize to threads only (never on sensor tip) during reinstallation.
2. 2

   Remove heat shields
   Remove heat shield bolts securing the exhaust manifold heat shields. There may be multiple shields depending on configuration. Carefully remove shields and set aside. Inspect shield mounting points for damage.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
3. 3

   Disconnect EGR tube (if equipped)
   If your vehicle is equipped with an EGR system, disconnect the EGR tube from the exhaust manifold. Remove the EGR tube fitting using a line wrench to prevent rounding. Remove and discard the old EGR gasket.
4. 4

   Disconnect turbocharger oil and coolant lines
   Carefully disconnect the turbocharger oil feed and drain lines. Have a drain pan ready as residual oil will drain. Disconnect turbocharger coolant lines and plug openings to prevent contamination. Support turbocharger with a strap or block to prevent stress on remaining connections.
   ⚠Turbocharger lines are under the manifold and easily damaged. Work carefully and do not force any connections.
5. 5

   Remove exhaust flange connection
   From underneath the vehicle, remove the exhaust flange bolts connecting the exhaust manifold to the downstream catalytic converter or exhaust pipe. Use penetrating oil and allow extra time if bolts are severely corroded. Support the exhaust pipe with a hanger or jack to prevent stress on remaining connections.
6. 6

   Support and remove exhaust hangers
   Remove exhaust hanger bolts or use a hanger removal tool to disconnect rubber hangers supporting the exhaust system. Allow the exhaust to hang freely or support with a jack to provide clearance for manifold removal.
7. 7

   Remove exhaust manifold mounting nuts
   Working from the hottest (center) nuts toward the coldest (outer) nuts, carefully remove all exhaust manifold mounting nuts. Use a systematic hot-to-cold pattern to prevent warping. If a stud begins to turn with the nut, stop and apply more penetrating oil. Allow extra time rather than risk breaking a stud in the cylinder head.
   ⚠Work hot-to-cold (center to ends) to minimize thermal stress and prevent manifold warping. Do not rush this step.
   Torque spec

   Exhaust Manifold Nuts30 Nm (22 lb-ft)
8. 8

   Remove exhaust manifold
   Carefully work the exhaust manifold away from the cylinder head studs. The manifold may be stuck to the head due to carbon buildup. Use a soft mallet to tap gently if needed, but avoid prying against the cylinder head surface. Once free, maneuver the manifold out of the engine bay, being careful not to damage surrounding components or turbocharger.
   ⚠Manifold is heavy and awkward to remove from the engine bay. Have a helper or support strap ready.
9. 9

   Inspect and replace studs if necessary
   Inspect all exhaust manifold studs for damage, thread wear, or bending. If any studs are damaged or were removed during the process, replace them now. Clean stud holes in the cylinder head with a thread chaser. Install new studs and torque to specification using a stud installation tool.
   Torque spec

   Exhaust Manifold Studs15 Nm (11 lb-ft)
10. 10

    Clean gasket surfaces
    Thoroughly clean all gasket surfaces on both the cylinder head and exhaust manifold using a plastic or brass gasket scraper. Remove all old gasket material and carbon deposits. Follow with brake parts cleaner and a clean lint-free cloth. Inspect surfaces for warping, cracks, or damage. Use a straightedge to check manifold flatness.
    ⚠Never use steel scrapers or abrasive pads on cylinder head gasket surfaces as they can cause damage requiring expensive head resurfacing.
11. 11

    Install new gaskets and manifold
    Position the new exhaust manifold gasket on the cylinder head studs. Carefully position the exhaust manifold onto the studs, ensuring gasket remains properly aligned. Start all manifold nuts by hand to ensure proper thread engagement before tightening any fasteners.
    ℹ️Some OEM gaskets have specific orientation. Check for UP markings or alignment tabs before installation.
12. 12

    Torque exhaust manifold nuts
    Apply a thin coat of high-temperature anti-seize to the manifold nut threads. Torque all exhaust manifold nuts to specification in a hot-to-cold pattern (center nuts first, working toward the ends) in three progressive stages: first to 10 Nm (7 lb-ft), then 20 Nm (15 lb-ft), then final torque of 30 Nm (22 lb-ft).
    Torque spec

    Exhaust Manifold Nuts30 Nm (22 lb-ft)
13. 13

    Reconnect exhaust flange
    Align the exhaust manifold outlet with the downstream catalytic converter or exhaust pipe. Install new gasket if required. Apply anti-seize to flange bolt threads and install bolts. Torque flange bolts to specification in a crisscross pattern.
14. 14

    Reconnect turbocharger lines and EGR
    Reconnect turbocharger oil feed and drain lines using new gaskets or seals as required. Reconnect turbocharger coolant lines. If equipped, install new EGR tube gasket and reconnect EGR tube to manifold, torquing fitting to specification.
15. 15

    Reinstall heat shields and oxygen sensors
    Install heat shields with new gaskets if required and torque heat shield bolts to specification. Apply anti-seize to oxygen sensor threads only (avoiding sensor tip) and install all oxygen sensors. Torque sensors to specification and reconnect all electrical connectors.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Reinstall exhaust hangers and torque hanger bolts to specification
2. Reconnect all electrical connectors to oxygen sensors and verify secure connection
3. Reinstall engine cover by pressing down firmly on retention clips
4. Reconnect negative battery terminal
5. Lower vehicle from jack stands

Verification

• Start engine and listen carefully for any exhaust leaks at the manifold-to-head and manifold-to-catalytic converter joints
• Allow engine to reach operating temperature and verify no leaks appear under thermal expansion
• Check for proper turbocharger operation with no unusual noises or smoking
• Verify all oxygen sensor readings are normal using a scan tool (should show active voltage fluctuation once warm)
• Inspect for any oil or coolant leaks at turbocharger connections
• Test drive vehicle and confirm normal power delivery and no check engine lights
• Re-check all fastener torque after first heat cycle (after engine cools)

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