Exhaust Manifold Studs

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

Warnings

Tools required

Parts

• Exhaust manifold stud kit × 1 — Use OEM Honda specification
• Exhaust manifold gasket × 1 — 18115-5BA-A00
• Turbocharger gasket × 1 — 18115-5BA-A01
• Exhaust flange gasket × 1 — Use OEM specification
• Heat shield gaskets × 2 — Use OEM specification
• Coolant × 1 — Honda Type 2 Blue
• Engine oil × 1 — Honda 0W-20

Fluids

• Honda Type 2 Coolant (Blue) — 2 qt
• Honda Genuine 0W-20 — 1 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Disconnect negative battery terminal and wait 3 minutes
3. Raise vehicle and secure on jack stands
4. Remove engine splash shield and undercovers
5. Drain approximately 2 quarts of coolant from radiator petcock to below turbocharger level
6. Remove air intake assembly and charge pipe from turbocharger
7. Apply penetrating oil to all exhaust studs and fasteners, let soak 30+ minutes

Procedure

1. 1

   Remove oxygen sensor
   Disconnect oxygen sensor electrical connector. Using oxygen sensor socket, remove primary oxygen sensor from exhaust manifold. Inspect sensor threads and replace if damaged.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
2. 2

   Disconnect turbocharger coolant lines
   Place drain pan under turbocharger. Loosen clamps and disconnect coolant inlet and outlet hoses from turbocharger. Plug hoses to prevent additional coolant loss. Expect approximately 0.5-1 quart of coolant to drain.
   ⚠Coolant may still be warm. Wear gloves to prevent burns.
3. 3

   Disconnect turbocharger oil lines
   Remove oil feed line banjo bolt from top of turbocharger. Remove oil return line from bottom of turbocharger housing. Plug openings immediately to prevent contamination. Have drain pan ready for residual oil.
   ℹ️Replace crush washers on oil feed banjo bolt during reassembly.
4. 4

   Remove heat shields
   Remove upper and lower heat shield bolts. Carefully remove heat shields from exhaust manifold and turbocharger area. Note orientation and location for reinstallation.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
5. 5

   Disconnect exhaust downpipe
   From underneath vehicle, remove exhaust flange bolts connecting downpipe to turbocharger outlet. Support downpipe with wire or jack to prevent strain on rear hangers. Remove and discard old gasket.
   ⚠Exhaust flange bolts are often seized. Use penetrating oil and heat if necessary. Replace bolts if damaged.
   Torque spec

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

   Remove turbocharger mounting fasteners
   Remove bolts securing turbocharger to exhaust manifold. There are typically 3-4 bolts. Support turbocharger weight while removing final bolt. Carefully remove turbocharger assembly and set aside on clean surface.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
7. 7

   Remove exhaust manifold
   Remove remaining exhaust manifold mounting nuts from cylinder head studs. Carefully pull manifold away from cylinder head. If stuck, use plastic mallet to gently tap manifold loose. Remove and discard old gasket material from cylinder head surface.
   ⚠Do not pry against aluminum cylinder head surface. Use only designated pry points or tap with soft mallet.
8. 8

   Assess and extract broken studs
   Identify broken or damaged studs in cylinder head. Apply penetrating oil and allow to soak. For studs broken below surface: center punch the broken stud, drill pilot hole with left-hand drill bit (may spin out stud), then use appropriately sized stud extractor. Apply heat to surrounding area if needed to break corrosion bond.
   ⚠️Drill perpendicular to cylinder head surface to avoid damaging threads. Start with small pilot bit and increase size gradually.
   ⚠If extractor breaks in stud, professional machine shop assistance may be required.
9. 9

   Clean and repair threads
   Once all old studs are removed, clean stud holes thoroughly with brake cleaner. Run appropriate tap through each hole to clean and restore threads (typically M8x1.25 or M10x1.25). Blow out holes with compressed air to remove debris. Inspect threads for damage.
   ℹ️If threads are severely damaged, thread repair insert (helicoil) may be required.
10. 10

    Install new exhaust manifold studs
    Apply small amount of anti-seize to lower 2/3 of new stud threads that enter cylinder head. Thread studs into cylinder head by hand until finger tight. Use two nuts locked together on stud to torque studs to proper tightness (typically hand-tight plus 1/4 turn). Do not over-tighten studs in aluminum head.
    ⚠Over-torquing studs during installation will strip aluminum threads. Studs should be snug but not heavily torqued.
11. 11

    Prepare gasket surfaces
    Clean all gasket mating surfaces on cylinder head and exhaust manifold with gasket scraper and brake cleaner. Ensure surfaces are completely clean and free of old gasket material, carbon deposits, and oil. Inspect manifold for warpage or cracks.
    ℹ️Do not use abrasive pads on aluminum surfaces. Use only approved gasket scrapers.
12. 12

    Install exhaust manifold
    Place new exhaust manifold gasket on cylinder head studs. Carefully position exhaust manifold over studs and gasket. Install new nuts on studs and torque in sequence from center outward in 2-3 stages to final specification.
    ℹ️Final torque specification for manifold nuts typically matches flange bolt specification of 45 Nm.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
13. 13

    Reinstall turbocharger
    Install new turbo-to-manifold gasket. Position turbocharger on exhaust manifold and install mounting bolts. Apply anti-seize to bolt threads. Torque bolts evenly in cross pattern to specification.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
14. 14

    Reconnect turbocharger lines and exhaust
    Reconnect turbocharger oil feed line with new crush washers. Reconnect oil return line. Reconnect coolant inlet and outlet hoses with new clamps. Install new exhaust flange gasket and reconnect downpipe. Apply anti-seize to flange bolt threads and torque to specification.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
15. 15

    Reinstall remaining components
    Reinstall heat shields and torque bolts to specification. Install oxygen sensor with anti-seize on threads only (not sensor tip) and torque to specification. Reconnect oxygen sensor electrical connector. Reinstall air intake assembly and charge pipe.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

    O2 Sensor45 Nm (33 lb-ft)

Reassembly

1. Refill coolant system with Honda Type 2 blue coolant to proper level
2. Check engine oil level and top off if necessary due to turbo oil line disconnection
3. Reinstall engine splash shields and undercovers
4. Reconnect negative battery terminal
5. Bleed cooling system by running engine to operating temperature with heater on high

Verification

• Start engine and listen for exhaust leaks at manifold and turbocharger connections
• Inspect all connection points for oil or coolant leaks while engine is running
• Check for proper turbocharger boost operation during test drive
• Verify no check engine light or turbocharger-related fault codes
• Re-check all torque specifications after engine reaches operating temperature and cools
• Verify coolant and oil levels after test drive

Related trouble codes on this vehicle

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