This procedure covers the removal and replacement of broken or damaged exhaust manifold studs on the 3.5L EcoBoost V6 engine, which commonly fail due to thermal stress and corrosion.

Warnings

Tools required

Parts

• Exhaust manifold studs × 1 — Ford OEM 3.5L EcoBoost exhaust stud kit
• Exhaust manifold gaskets × 2 — Use OEM specification
• Turbocharger-to-manifold gaskets × 2 — Use OEM specification
• Exhaust downpipe flange gasket × 1 — Use OEM specification
• Heat shield gaskets/insulators × 2 — Use OEM specification

Preparation

1. Disconnect negative battery cable and wait 10 minutes for airbag system to discharge
2. Raise and support vehicle on jack stands at all four corners
3. Remove engine belly pan and front skid plate if equipped
4. Remove front wheels for improved access to lower exhaust components
5. Apply penetrating oil to all exhaust flange bolts, O2 sensors, and visible manifold studs. Allow to soak for at least 30 minutes
6. Drain approximately 2 quarts of coolant from radiator to allow turbocharger coolant line removal
7. Take multiple photographs of turbocharger oil and coolant line routing for reference during reassembly

Procedure

1. 1

   Remove air intake system and accessories
   Remove the air filter housing and intake tubes to access the engine. Disconnect the charge air cooler outlet tube from both turbochargers. Remove the upper radiator sight shield. Disconnect any wiring harnesses or vacuum lines that obstruct access to the exhaust manifolds and turbochargers.
2. 2

   Disconnect oxygen sensors
   Locate the four oxygen sensors (two upstream pre-turbo, two downstream post-turbo). Disconnect the electrical connectors. Using an oxygen sensor socket, carefully remove all four O2 sensors. If sensors are seized, apply additional penetrating oil and allow to soak, or use a propane torch to carefully heat the bung (engine must be cold).
   Torque spec

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

   Remove heat shields
   Remove the exhaust manifold heat shields from both banks. These are secured with 8mm bolts. The shields may be brittle from heat cycling, so work carefully to avoid breaking mounting tabs. Remove any upper engine covers that interfere with manifold access.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
4. 4

   Disconnect turbocharger oil and coolant lines
   Working on one side at a time, disconnect the turbocharger oil feed line from the top of the turbocharger and the oil drain tube from the bottom. Disconnect the coolant supply and return lines. Have rags ready to catch residual oil and coolant. Cap or plug all openings immediately to prevent contamination.
   ⚠Oil drain tubes are often seized and may require careful prying. Do not damage the turbocharger CHRA housing.
5. 5

   Support and remove turbochargers
   Install a turbocharger support fixture or use an appropriate jack with wood block to support the weight of the turbocharger. Remove the bolts securing the turbocharger to the exhaust manifold. Carefully lower and remove each turbocharger from the vehicle. The turbos are heavy and have limited clearance.
   Torque spec

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

   Disconnect exhaust downpipes
   From underneath the vehicle, remove the bolts securing the Y-pipe/downpipe assembly to the turbocharger outlets. Remove the exhaust hanger bolts as needed. Lower the exhaust system enough to provide clearance for manifold removal. You may need to remove the entire Y-pipe assembly depending on which bank you are working on.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)

   Hanger Bolts23 Nm (17 lb-ft)
7. 7

   Remove exhaust manifolds
   Remove the remaining nuts securing the exhaust manifolds to the cylinder head. On the 3.5L EcoBoost, each manifold is secured by 8 studs. Work in a crisscross pattern to evenly release tension. Note which studs are broken - they will typically break flush with or below the surface of the head. Remove the manifolds and gaskets.
   ℹ️Manifolds may be stuck to the head due to carbon buildup. Use a soft mallet and pry bar to gently break the seal. Do not pry against machined sealing surfaces.
8. 8

   Extract broken studs
   For each broken stud, center-punch the exact center of the stud remnant. Start with a small left-hand drill bit (1/8 inch) and carefully drill into the center of the broken stud. Often the stud will begin to unscrew as you drill due to the left-hand rotation. If not, progressively increase drill bit size and use a screw extractor. Alternatively, drill out the entire stud and re-tap the hole if severely damaged. Cover adjacent cylinder head ports with tape and rags to prevent metal shavings from entering.
   ⚠️Metal shavings in the combustion chamber or exhaust port will cause engine damage. Work carefully and vacuum thoroughly after each drilling operation.
   ⚠If a drill bit or extractor breaks off in the stud, professional machining may be required. Work slowly and use cutting oil.
9. 9

   Clean and inspect cylinder head surfaces
   Thoroughly vacuum the area around all stud holes. Use a wire brush to clean the cylinder head mounting surface, removing all old gasket material and carbon deposits. Do not gouge the sealing surface. Clean all stud holes with a tap to chase the threads. Inspect the head surface for cracks or warping. Vacuum again to ensure all debris is removed from ports and bolt holes.
10. 10

    Install new exhaust manifold studs
    Apply a small amount of anti-seize compound to the threads of new studs (thread end that goes into the head only, not the nut end). Thread each stud into the cylinder head by hand first to ensure proper threading. Use a stud installation tool to tighten studs to proper depth - studs should protrude equally and seat fully in the head. Follow manufacturer specifications for stud installation torque if provided with the stud kit.
    ⚠Do not apply anti-seize to the nut end of the stud where the manifold mounts. This can cause improper torque readings and loosening.
11. 11

    Install exhaust manifolds with new gaskets
    Install new exhaust manifold gaskets on the cylinder head, ensuring proper orientation. Carefully position the exhaust manifold onto the studs. Install new nuts finger-tight on all studs. Torque the manifold nuts in a crisscross pattern from the center outward in three progressive steps: first to 15 Nm, then 30 Nm, and finally to the specified torque. Repeat for the second bank.
12. 12

    Reinstall turbochargers
    Install new turbocharger-to-manifold gaskets. Position each turbocharger onto the exhaust manifold using the support fixture. Install bolts with anti-seize and torque in a crisscross pattern. Reconnect oil feed lines, oil drain tubes, and coolant lines in reverse order of removal. Ensure all fittings are properly sealed.
    Torque spec

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

    Reconnect exhaust system
    Raise the downpipe/Y-pipe assembly into position with new flange gasket installed. Install and torque the exhaust flange bolts with anti-seize compound applied to threads. Reinstall exhaust hangers and torque hanger bolts.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)

    Hanger Bolts23 Nm (17 lb-ft)
14. 14

    Install heat shields and oxygen sensors
    Reinstall heat shields with new insulators if needed, torquing bolts to specification. Apply anti-seize compound to the threads only (not the sensor tip) of each oxygen sensor. Install all four O2 sensors and torque to specification. Reconnect electrical connectors.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

    O2 Sensor45 Nm (33 lb-ft)
15. 15

    Reinstall accessories and refill coolant
    Reinstall the charge air cooler tubes, air intake system, and all wiring harnesses and vacuum lines. Refill cooling system with Motorcraft Orange Coolant to proper level. Reinstall engine covers, belly pan, skid plate, and wheels. Reconnect the battery.

Reassembly

1. Double-check that all exhaust connections are tight and all sensors are reconnected
2. Verify all turbocharger oil and coolant lines are properly secured with no leaks at fittings
3. Ensure no tools or rags were left in the engine bay
4. Bleed cooling system according to Ford procedure to eliminate air pockets in turbocharger coolant lines

Verification

• Start the engine and listen for exhaust leaks at manifold and turbocharger connections. A stethoscope can help locate small leaks
• Check for oil leaks at turbocharger oil feed and drain connections while engine is running
• Monitor coolant level and check for leaks at turbocharger coolant lines after engine reaches operating temperature
• Verify all oxygen sensor codes clear and sensors are reading properly using a scan tool
• Road test vehicle under light and moderate load, listening for unusual noises or checking for loss of boost pressure
• After first 50-100 miles, re-inspect all exhaust connections for signs of leaking (soot marks) and re-torque if necessary

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