Exhaust Manifold

This procedure covers removal and installation of the exhaust manifold on the 2018-2024 Honda Accord 1.5L turbo engine, including turbocharger assembly removal and gasket replacement.

Warnings

Tools required

Parts

• Exhaust manifold gasket × 1 — Use OEM specification
• Turbocharger-to-manifold gasket × 1 — Use OEM specification
• Exhaust flange gasket × 1 — Use OEM specification
• Heat shield gasket (if equipped) × 1 — Use OEM specification
• Exhaust manifold nuts × 8 — Replace if corroded
• Anti-seize compound × 1 — High-temperature rated

Fluids

• Honda Type 2 Coolant (Blue) — 1 qt

Preparation

1. Ensure engine is completely cold (not run for at least 2 hours)
2. Disconnect negative battery terminal and wait 3 minutes
3. Raise vehicle and support securely on jack stands
4. Remove engine under cover and splash shields
5. Apply penetrating oil to all exhaust fasteners and allow to soak
6. Drain approximately 1 quart of coolant from radiator drain to below turbocharger level

Procedure

1. 1

   Remove engine cover and intake components
   Remove the engine cover by pulling upward on the front clips. Disconnect the intake air duct from the turbocharger inlet. Remove the air filter housing assembly and set aside. This provides access to the top of the exhaust manifold and turbocharger.
   Torque spec

   Cover Bolts15 Nm (11 lb-ft)
2. 2

   Disconnect oxygen sensor
   Locate the upstream oxygen sensor on the exhaust manifold. Disconnect the electrical connector by pressing the release tab. Using an O2 sensor socket, carefully unthread the sensor from the manifold. Work slowly to avoid breaking the sensor body. Set sensor aside in a safe location.
   ⚠O2 sensor threads are fragile. If sensor is seized, apply heat carefully and work sensor back and forth to prevent thread damage
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
3. 3

   Disconnect turbocharger coolant lines
   Place drain pan below turbocharger. Disconnect the coolant feed line from the top of the turbocharger by loosening the banjo bolt. Disconnect the coolant return line from the bottom of the turbocharger. Allow coolant to drain completely. Plug lines with clean rags to prevent contamination.
   ⚠Coolant will spill during this step. Ensure drain pan is properly positioned
4. 4

   Disconnect turbocharger oil lines
   Disconnect the oil feed line from the top of the turbocharger center housing. Disconnect the oil return line from the bottom of the turbocharger. Some oil will drain from these lines. Cap or plug all oil line openings immediately to prevent contamination and debris entry.
   ⚠Keep oil line openings clean. Any debris entering the turbocharger oil system will cause premature failure
5. 5

   Remove exhaust downpipe connection
   Working from underneath the vehicle, locate the three-bolt flange connection between the turbocharger outlet and the exhaust downpipe. Apply penetrating oil if not already done. Remove the three flange bolts while supporting the downpipe weight. Lower the downpipe slightly and support with wire or jack stand.
   ⚠Exhaust flange bolts are frequently seized. Use penetrating oil and heat if necessary to avoid breaking bolts
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
6. 6

   Remove heat shield
   Remove all heat shield bolts securing the exhaust manifold heat shield. There are typically 4-6 bolts depending on configuration. Carefully remove the heat shield, noting the position of any spacers or washers. Inspect shield for damage and replace if severely corroded.
   Torque spec

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

   Disconnect turbocharger from exhaust manifold
   Remove the bolts securing the turbocharger to the exhaust manifold (typically 3-4 bolts). Support the turbocharger weight while removing the final bolt. Carefully separate the turbocharger from the manifold and remove the assembly from the vehicle. Remove and discard the turbo-to-manifold gasket.
   ⚠Turbocharger assembly is heavy and awkward to handle. Avoid dropping or impacting the turbine/compressor wheels
   Torque spec

   Mounting Bolts45 Nm (33 lb-ft)
8. 8

   Remove exhaust manifold nuts
   Working from top and bottom of engine bay, remove all eight exhaust manifold nuts securing the manifold to the cylinder head. Work in a cold-to-hot pattern (start from the ends and work toward the center) to reduce stress on studs. If a stud begins to turn, stop immediately and apply penetrating oil and heat before continuing.
   ⚠Manifold studs commonly break on this engine. Work slowly and carefully. If a stud breaks, extraction will add significant time to the repair
   Torque spec

   Exhaust Manifold Nuts30 Nm (22 lb-ft)
9. 9

   Remove exhaust manifold
   Carefully pull the exhaust manifold away from the cylinder head. It may be stuck due to carbon buildup. Gently tap with a rubber mallet if necessary to break the seal. Remove the manifold from the engine bay. Remove and discard the old manifold gasket.
   ℹ️Manifold removal clearance is tight. May need to angle manifold to clear surrounding components
10. 10

    Clean mating surfaces
    Thoroughly clean the cylinder head exhaust port mating surface using a plastic scraper. Remove all old gasket material and carbon buildup. Do not use metal scrapers that could gouge the aluminum surface. Clean the manifold mating surface similarly. Wipe both surfaces clean with brake cleaner or acetone. Inspect cylinder head for cracks or damage.
    ⚠Do not allow debris to fall into exhaust ports. Cover ports with clean rags during cleaning
11. 11

    Inspect and prepare new/replacement manifold
    If installing a new manifold, verify all studs are present and threads are clean. If reusing the original manifold, inspect for cracks, warping, and damaged stud threads. Clean all stud threads with a wire brush. Apply a thin coat of anti-seize to all manifold stud threads.
    Torque spec

    Exhaust Manifold Nuts30 Nm (22 lb-ft)
12. 12

    Install exhaust manifold
    Position the new exhaust manifold gasket onto the cylinder head, aligning all holes carefully. Carefully position the exhaust manifold onto the studs and press firmly against the gasket. Start all eight manifold nuts by hand to ensure proper thread engagement. Tighten nuts in a hot-to-cold pattern (center outward) to the specified torque in at least two stages: first to 15 Nm, then final torque to 30 Nm.
    ℹ️Verify tightening sequence with service manual. Improper sequence can cause gasket failure or manifold warping
    Torque spec

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

    Install turbocharger to manifold
    Install new turbocharger-to-manifold gasket. Position the turbocharger onto the exhaust manifold, aligning the mounting holes. Apply anti-seize to the turbo mounting bolt threads. Install and tighten bolts to specification. Ensure turbocharger is seated squarely against the manifold before final tightening.
    Torque spec

    Mounting Bolts45 Nm (33 lb-ft)
14. 14

    Reconnect turbocharger oil and coolant lines
    Remove plugs from oil and coolant line openings. Reconnect the oil feed line to the top of the turbocharger with new crush washers if applicable. Reconnect the oil return line to the bottom of the turbocharger. Reconnect both coolant lines using new sealing washers. Tighten all connections securely but do not overtighten aluminum fittings.
    ⚠Ensure all line connections are clean and free of debris before reconnecting to turbocharger
15. 15

    Install heat shield and reconnect downpipe
    Install the heat shield with new gasket if applicable, tightening bolts to specification. Install new exhaust flange gasket between turbocharger outlet and downpipe. Apply anti-seize to flange bolt threads. Install and tighten the three flange bolts to specification following the proper sequence.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

    Exhaust Flange Bolts45 Nm (33 lb-ft)
16. 16

    Install oxygen sensor
    Apply a thin coating of anti-seize compound to the O2 sensor threads (avoid getting anti-seize on the sensor tip). Thread the oxygen sensor into the manifold by hand until snug. Use the O2 sensor socket to tighten to the specified torque. Reconnect the electrical connector, ensuring it clicks into place securely.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
17. 17

    Reinstall intake components and refill coolant
    Reinstall the air filter housing assembly and intake duct to the turbocharger. Secure with all clips and fasteners. Refill the cooling system with Honda Type 2 coolant to the proper level. Reinstall the engine cover. Reinstall all under covers and splash shields.

Reassembly

1. Double-check all fastener torque values, especially exhaust manifold nuts and flange bolts
2. Verify all electrical connectors are properly seated and locked
3. Ensure no tools or rags were left in the engine bay
4. Reconnect negative battery terminal

Verification

• Start engine and allow to idle. Listen for exhaust leaks at manifold, turbo, and downpipe connections
• Check for coolant and oil leaks around turbocharger connections while engine is running
• Monitor coolant level and top off as needed after engine reaches operating temperature
• Perform a test drive and verify normal turbocharger boost operation with no unusual noises
• Re-check all fasteners after first heat cycle (50-100 miles) to ensure proper torque retention
• Verify no exhaust odor in cabin and no visible exhaust smoke from engine bay

Related trouble codes on this vehicle

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