This procedure covers the removal and replacement of exhaust manifold studs on a 2019-2024 Toyota RAV4 with the 2.5L I4 gasoline engine, including removal of the exhaust manifold and heat shields.

Warnings

Tools required

Parts

• Exhaust manifold studs × 8 — Use OEM specification
• Exhaust manifold gasket × 1 — Use OEM specification
• Exhaust flange gasket × 1 — Use OEM specification
• Heat shield gaskets (if equipped) × 1 — Use OEM specification
• O2 sensor (if damaged) × 1 — Use OEM specification

Preparation

1. Ensure engine is completely cold to the touch (minimum 2 hours cool-down time)
2. Disconnect negative battery terminal and secure cable away from battery post
3. Raise and support vehicle on jack stands at manufacturer-specified lift points
4. Remove engine under cover/splash shield if equipped
5. Apply penetrating oil to all exhaust manifold studs, flange bolts, heat shield bolts, and oxygen sensor threads. Allow to soak for minimum 30 minutes (overnight soak recommended for high-mileage vehicles)
6. Remove engine cover and air intake assembly from upper side for better access
7. Place drain pan under work area to catch any debris or fluids

Procedure

1. 1

   Remove oxygen sensor
   Disconnect the oxygen sensor electrical connector located on the exhaust manifold or front pipe. Using a 22mm oxygen sensor socket, carefully remove the upstream oxygen sensor from the exhaust manifold. Apply steady counterclockwise force; do not force if resistance is excessive. If sensor will not turn, apply additional penetrating oil and heat cycle the area with a heat gun (do not use torch near sensor).
   ⚠O2 sensors are fragile. Do not use excessive force or impact tools as this can damage the internal element.
2. 2

   Remove heat shields
   Remove all heat shield bolts securing the upper and lower exhaust manifold heat shields. There are typically 3-5 bolts per shield. Remove the heat shields and set aside. Inspect shields for damage or excessive corrosion.
3. 3

   Disconnect exhaust front pipe
   Working from underneath the vehicle, locate the exhaust flange connection between the exhaust manifold and front pipe. Remove the two or three flange bolts/nuts connecting the front pipe to the manifold. Support the front pipe weight with a jack or wire to prevent stress on downstream hangers. Separate the flange connection and remove the old gasket.
4. 4

   Remove exhaust manifold stay bracket
   Locate the exhaust manifold support bracket that connects the manifold to the engine block or transmission housing. Remove the bolts securing this bracket (typically 2-3 bolts). Remove the bracket to allow manifold removal clearance.
5. 5

   Remove exhaust manifold nuts
   Working from the top and side of the engine, remove all exhaust manifold nuts from the studs. There are typically 8 nuts securing the manifold to the cylinder head. Work slowly and apply additional penetrating oil if any nut shows excessive resistance. Use a six-point socket for best grip. Remove nuts in a crisscross pattern starting from the center outward to prevent warping stress.
   ⚠If a nut seizes and the stud begins to turn instead, stop immediately and apply more penetrating oil. Continue attempts may break the stud.
6. 6

   Remove exhaust manifold
   Carefully pull the exhaust manifold away from the cylinder head. It may require gentle prying or tapping with a rubber mallet to break the gasket seal. Once free, remove the manifold from the engine compartment. Remove and discard the old exhaust manifold gasket from the cylinder head surface.
7. 7

   Assess and remove damaged studs
   Inspect all exhaust manifold studs in the cylinder head. Identify any broken, damaged, or stripped studs that require replacement. For broken studs flush with or below the surface: center punch the exact center of the broken stud. Using a left-hand drill bit starting with 1/8-inch and progressing to appropriate size, drill into the center of the stud. Often the stud will begin to unscrew as you drill. If not, use an appropriate size stud extractor (easy-out) to remove the remaining stud. For studs protruding above surface: use locking pliers or a stud removal tool to carefully unscrew.
   ⚠️Drilling must be perfectly centered and straight to avoid damaging cylinder head threads. Use a drill press or drill guide if available.
   ⚠Easy-out extractors are hardened and brittle. If an extractor breaks off in the stud, professional machine shop intervention may be required.
8. 8

   Clean and chase cylinder head threads
   Use a wire brush to thoroughly clean all stud holes in the cylinder head. Remove all carbon buildup, old gasket material, and corrosion from the mounting surface using a gasket scraper. Use a shop vacuum to remove debris from stud holes. Run a M10x1.25 thread chaser or tap through each stud hole to clean and restore threads. Clean threads again with compressed air or vacuum to ensure no metal shavings remain in the holes.
   ⚠Do not allow any debris to fall into the cylinder head oil or coolant passages. Cover nearby openings with shop rags.
9. 9

   Install new exhaust manifold studs
   Apply a small amount of anti-seize compound to the threads of new exhaust manifold studs (thread portion that goes into cylinder head only). Thread each new stud into the cylinder head by hand to ensure proper thread engagement. Use two nuts locked together on the stud or a stud installation tool to tighten studs firmly into the cylinder head. Studs should be seated fully with approximately equal thread length protruding from the head surface. Remove installation nuts if used.
   ℹ️Apply anti-seize only to threads entering the head, not to the portion where the manifold nuts will be installed.
10. 10

    Clean exhaust manifold mating surface
    Thoroughly clean the exhaust manifold mating surface with a wire brush and gasket scraper. Remove all old gasket material and carbon deposits. Inspect manifold for cracks, especially around the ports and flange areas. Clean the exhaust flange surface where it connects to the front pipe.
11. 11

    Install new gasket and exhaust manifold
    Position the new exhaust manifold gasket onto the cylinder head, aligning all port openings and stud holes. Carefully position the exhaust manifold over the studs and onto the gasket. Ensure manifold is fully seated against the gasket and cylinder head surface with no gaps or misalignment.
12. 12

    Install and torque manifold nuts
    Install all exhaust manifold nuts onto the studs and thread by hand. Apply a small amount of anti-seize to the nut threads. Tighten nuts in a crisscross pattern starting from the center outward. First pass: snug all nuts finger-tight plus 1/4 turn. Second pass: torque all nuts to half specification. Third pass: torque all nuts to final specification of 47 Nm (35 lb-ft) in crisscross sequence.
    ℹ️While these are nuts on studs, they follow the same torque specification as the flange bolts at 47 Nm.
    Torque spec

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

    Reinstall manifold support bracket
    Position the exhaust manifold support bracket back into place and install mounting bolts. Tighten support bracket bolts securely.
14. 14

    Reconnect exhaust front pipe
    Install new exhaust flange gasket between the manifold and front pipe. Align the front pipe to the manifold flange. Apply anti-seize compound to the flange bolt threads. Install flange bolts and torque to specification.
    Torque spec

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

    Install heat shields and oxygen sensor
    Reinstall the upper and lower heat shields and torque heat shield bolts to specification. Apply anti-seize compound to the oxygen sensor threads only (avoid getting anti-seize on the sensor tip). Install the oxygen sensor and torque to specification. Reconnect the oxygen sensor electrical connector.
    ⚠Do not allow anti-seize or any contaminant to contact the oxygen sensor tip or internal element.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

    O2 Sensor45 Nm (33 lb-ft)

Reassembly

1. Reinstall air intake assembly and engine cover
2. Reinstall engine under cover/splash shield
3. Lower vehicle from jack stands
4. Reconnect negative battery terminal
5. Start engine and allow to idle while checking for exhaust leaks at manifold gasket and flange connections
6. Clear any diagnostic trouble codes related to oxygen sensor disconnection using OBD-II scanner if check engine light appears

Verification

• Start engine and listen for exhaust leaks at the manifold-to-head interface and manifold-to-pipe flange. There should be no hissing or ticking sounds indicating leak
• Allow engine to reach operating temperature and verify no leaks develop under heat expansion
• Verify oxygen sensor is functioning properly with no diagnostic codes present
• Perform a test drive and confirm normal engine performance with no exhaust odors in cabin
• After first heat cycle, re-check manifold nut torque when engine is cold (optional but recommended for critical applications)

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