Exhaust Gasket - Front

Replace the front exhaust gasket between the exhaust manifolds and front exhaust pipes on a 2014-2018 Chevrolet Silverado 1500 with 5.3L V8 engine.

Warnings

Tools required

Parts

• Exhaust manifold to Y-pipe gasket kit × 1 — ACDelco 19330095 or equivalent donut gaskets
• Exhaust flange bolts/studs × 1 — Replace if damaged or heavily corroded

Preparation

1. Park vehicle on level surface and allow exhaust system to cool completely (minimum 2 hours after running)
2. Apply wheel chocks to rear wheels
3. Raise front of vehicle and support securely on jack stands at manufacturer-recommended lift points
4. Spray all exhaust flange bolts and oxygen sensor threads with penetrating oil and allow to soak for 15-30 minutes

Procedure

1. 1

   Remove front oxygen sensors
   Locate the oxygen sensors on both driver and passenger side exhaust manifolds just upstream of the front exhaust flange. Disconnect the electrical connectors by pressing the release tab. Using an oxygen sensor socket, carefully remove both front oxygen sensors. Turn counterclockwise and support the sensor to avoid damaging the wiring harness.
2. 2

   Remove heat shields if equipped
   If heat shields are present over the exhaust manifold-to-pipe flanges, remove the mounting bolts. There are typically 2-3 bolts per shield. Set shields aside for reinstallation.
3. 3

   Support exhaust system
   Position a floor jack with a block of wood under the catalytic converter/Y-pipe assembly to support the weight of the exhaust system. Raise jack just enough to take the weight off the front flange connection without lifting the vehicle.
   ⚠Properly support the exhaust system to prevent it from dropping and causing injury or damaging oxygen sensor wiring when the flange bolts are removed.
4. 4

   Remove exhaust flange bolts
   Locate the three bolts/studs at each exhaust manifold-to-front pipe flange connection (driver and passenger sides). Using an 15mm socket with extensions, remove all six flange bolts. Work slowly and apply additional penetrating oil if bolts are difficult to turn. If studs break, they will need to be extracted or drilled out.
5. 5

   Separate exhaust pipes from manifolds
   With all flange bolts removed, carefully lower the exhaust Y-pipe assembly slightly using the floor jack. Separate the front exhaust pipes from both exhaust manifolds. You may need to wiggle the pipes and use a pry bar to break the seal if gaskets are stuck.
6. 6

   Remove old gaskets and clean surfaces
   Remove the old exhaust gaskets (donut-style gaskets) from the manifold outlets and pipe inlets. Use a gasket scraper and wire brush to clean all mating surfaces on both the manifold flanges and exhaust pipe flanges. Remove all carbon buildup, old gasket material, and corrosion. Surfaces must be clean and smooth for proper sealing.
7. 7

   Inspect studs and flanges
   Inspect the exhaust manifold studs and flange surfaces for damage, cracks, or excessive corrosion. Check that all studs are present and threads are in good condition. Replace any damaged studs before proceeding. Inspect exhaust pipe flanges for warping or damage.
8. 8

   Install new exhaust gaskets
   Position new donut-style exhaust gaskets onto the exhaust manifold outlet flanges on both driver and passenger sides. Ensure gaskets are properly seated in the recessed area of the manifold outlet. The gaskets should fit snugly without gaps.
9. 9

   Reconnect exhaust pipes to manifolds
   Using the floor jack, carefully raise the exhaust Y-pipe assembly up to align with both exhaust manifolds. Guide the front pipe flanges onto the manifold outlets, compressing the new gaskets. Align all bolt holes. This may require some adjustment and wiggling to get proper alignment on both sides simultaneously.
10. 10

    Install and torque flange bolts
    Apply anti-seize compound to the threads of all six exhaust flange bolts. Start all bolts by hand to ensure proper thread engagement. Tighten bolts in a star/crossing pattern to ensure even gasket compression. Torque all four flange bolts to approximately 15 ft-lbs (20 Nm), or to GM-specified value, using a torque wrench.
    Torque spec

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

    Reinstall heat shields
    If heat shields were removed, position them back over the exhaust flange connections and install mounting bolts. Torque heat shield bolts to specification.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)
12. 12

    Reinstall oxygen sensors
    Apply a small amount of anti-seize compound to the oxygen sensor threads only (do not get anti-seize on the sensor tip). Thread both front oxygen sensors back into the exhaust manifolds by hand, then tighten to specification using the oxygen sensor socket and torque wrench. Reconnect the electrical connectors to both sensors, ensuring the clips lock securely.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)

Reassembly

1. Remove floor jack from under exhaust system
2. Verify all exhaust connections are secure and no tools or parts are left in the work area
3. Lower vehicle from jack stands

Verification

• Start engine and allow to idle for 2-3 minutes while listening for exhaust leaks at the front flange connections
• Check for visible exhaust smoke or fumes escaping from the gasket area
• Perform a test drive and re-check for exhaust leaks while engine is at operating temperature
• Verify no check engine light or oxygen sensor codes are present after test drive

Related trouble codes on this vehicle

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