Exhaust Gasket - Front

This procedure covers replacement of the front exhaust gaskets between the exhaust manifolds and exhaust pipes on the 2015-2020 Ford F-150 5.0L V8 Coyote engine.

Warnings

Tools required

Parts

• Front exhaust flange gasket - left side × 1 — Use OEM specification
• Front exhaust flange gasket - right side × 1 — Use OEM specification
• Exhaust flange bolts/nuts (if corroded) × 8 — M10 flanged nuts

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow exhaust system to cool completely (minimum 2 hours after engine operation)
3. Raise front of vehicle and support securely on jack stands
4. Apply penetrating oil to all exhaust flange bolts/nuts and O2 sensor threads, allow to soak for 15-30 minutes

Procedure

1. 1

   Remove driver side front O2 sensor
   Disconnect the electrical connector from the upstream (front) O2 sensor on the driver side exhaust manifold. Using a 22mm O2 sensor socket, carefully remove the O2 sensor from the exhaust pipe just downstream of the flange connection. If sensor is seized, apply heat carefully with a propane torch while avoiding the wiring harness.
2. 2

   Remove passenger side front O2 sensor
   Disconnect the electrical connector from the upstream O2 sensor on the passenger side exhaust manifold. Using a 22mm O2 sensor socket, carefully remove the O2 sensor from the exhaust pipe just downstream of the flange connection.
3. 3

   Remove driver side exhaust flange fasteners
   Locate the exhaust flange connection between the driver side exhaust manifold and the front exhaust pipe. Remove the four nuts securing the flange connection. Support the exhaust pipe to prevent it from dropping when the last fastener is removed.
4. 4

   Separate driver side exhaust connection
   Carefully pull the exhaust pipe away from the manifold flange to separate the connection. The old gasket may stick to either surface. Remove and discard the old gasket.
5. 5

   Remove passenger side exhaust flange fasteners
   Locate the exhaust flange connection between the passenger side exhaust manifold and the front exhaust pipe. Remove the four nuts securing the flange connection. Support the exhaust pipe to prevent stress on remaining connections.
6. 6

   Separate passenger side exhaust connection
   Carefully pull the exhaust pipe away from the manifold flange to separate the connection. Remove and discard the old gasket.
7. 7

   Clean flange surfaces
   Using a wire brush and gasket scraper, thoroughly clean both the exhaust manifold flange and exhaust pipe flange surfaces on both sides. Remove all old gasket material, carbon deposits, and corrosion. The surfaces must be clean and flat for proper sealing.
8. 8

   Install new driver side gasket and connect flange
   Position the new exhaust flange gasket over the manifold studs on the driver side. Align the exhaust pipe flange with the manifold flange and carefully slide it into position over the studs. Thread all four nuts onto the studs by hand.
9. 9

   Install new passenger side gasket and connect flange
   Position the new exhaust flange gasket over the manifold studs on the passenger side. Align the exhaust pipe flange with the manifold flange and carefully slide it into position over the studs. Thread all four nuts onto the studs by hand.
10. 10

    Torque driver side flange fasteners
    Apply anti-seize compound to the threads of the flange nuts. Using a torque wrench, tighten the four nuts in a cross pattern (alternating opposite nuts) to ensure even gasket compression and proper sealing.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
11. 11

    Torque passenger side flange fasteners
    Apply anti-seize compound to the threads of the flange nuts. Using a torque wrench, tighten the four nuts in a cross pattern to ensure even gasket compression and proper sealing.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
12. 12

    Reinstall driver side O2 sensor
    Apply a small amount of anti-seize compound to the threads of the O2 sensor only (keep compound away from the sensor tip). Thread the sensor into the exhaust pipe by hand, then torque to specification using the O2 sensor socket. Reconnect the electrical connector.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
13. 13

    Reinstall passenger side O2 sensor
    Apply a small amount of anti-seize compound to the threads of the O2 sensor only. Thread the sensor into the exhaust pipe by hand, then torque to specification. Reconnect the electrical connector.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)

Reassembly

1. Verify all exhaust connections are secure and all electrical connectors are properly engaged
2. Lower vehicle from jack stands
3. Ensure no tools or parts remain in engine bay or under vehicle

Verification

• Start engine and listen for exhaust leaks at the front flange connections while engine is cold
• Allow engine to reach operating temperature and check for leaks again, as gaskets will compress under heat
• Verify no check engine light or O2 sensor codes are present
• Check that exhaust system is properly supported and not contacting frame or body components

Related trouble codes on this vehicle

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