Exhaust Manifold Studs

Replace exhaust manifold studs on both banks of the 3.0L V6 Twin Turbo engine, including removal of turbochargers, exhaust components, and heat shields to access and replace damaged or worn studs.

Warnings

Tools required

Parts

• Exhaust manifold stud kit (left bank) × 1 — Use OEM specification
• Exhaust manifold stud kit (right bank) × 1 — Use OEM specification
• Exhaust manifold gasket set × 2 — Use OEM specification
• Turbocharger to manifold gasket (left) × 1 — Use OEM specification
• Turbocharger to manifold gasket (right) × 1 — Use OEM specification
• Exhaust flange gaskets × 2 — Use OEM specification
• Heat shield gaskets/seals × 2 — Use OEM specification
• Oil drain plug crush washer × 1 — Use OEM specification

Fluids

• Selenia Racing 10W-60 — 5.5 qt

Preparation

1. Ensure engine is completely cold (minimum 6 hours after last operation)
2. Disconnect negative battery terminal and wait 10 minutes for system discharge
3. Raise vehicle on lift and secure with safety stands
4. Remove engine undertray and side panels for access
5. Apply penetrating oil to all exhaust manifold studs, nuts, and flange connections on both banks
6. Drain engine oil completely and remove oil filter
7. Remove engine cover and intake plenum for access to rear of engine
8. Disconnect air intake ducts to both turbochargers
9. Label and photograph all vacuum lines, electrical connectors, and coolant lines connected to turbochargers

Procedure

1. 1

   Remove oxygen sensors
   Disconnect electrical connectors from all four oxygen sensors (two per bank, pre and post-cat). Using oxygen sensor socket, carefully remove sensors from exhaust manifolds and downpipes. Apply penetrating oil if sensors resist removal. Store sensors in clean area to prevent contamination of sensor elements.
   Torque spec

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

   Disconnect turbocharger oil and coolant lines
   Place drain pans under turbochargers. Starting with right bank, disconnect oil feed line from top of turbo and oil return line from bottom. Disconnect coolant inlet and outlet lines. Cap all openings immediately to prevent contamination. Repeat for left bank. Expect approximately 0.5 quarts of oil drainage per turbo.
   ⚠Oil return lines are under slight pressure and will drain quickly. Position drain pan accordingly.
3. 3

   Remove exhaust downpipes and heat shields
   From underneath vehicle, remove exhaust hanger bolts supporting downpipes. Remove flange bolts connecting downpipes to turbocharger outlets on both banks. Lower downpipes away from turbos. Remove heat shield bolts and carefully extract heat shields from both banks, working shields around turbos and chassis components.
   Torque spec

   Hanger Bolts22 Nm (16 lb-ft)

   Exhaust Flange Bolts45 Nm (33 lb-ft)

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

   Remove turbochargers from manifolds
   Remove exhaust flange bolts connecting turbochargers to exhaust manifolds (typically 3-4 bolts per turbo). Carefully separate turbochargers from manifolds, supporting turbo weight. Remove and discard old gaskets. Inspect turbo housings for cracks or damage. Set turbochargers aside in protected area.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
5. 5

   Remove exhaust manifold assemblies
   Apply final application of penetrating oil to manifold nuts. Starting from center and working outward, carefully remove manifold nuts from studs on right bank. If nuts bind on studs, apply heat carefully with torch while applying penetrating oil. Once all nuts removed, carefully extract manifold from cylinder head. Repeat process for left bank. Note location of any broken or damaged studs.
   ⚠Manifolds are heavy and awkward. Support weight fully before removing final fasteners to prevent dropping.
   Torque spec

   Manifold Nuts35 Nm (26 lb-ft)
6. 6

   Extract damaged studs from cylinder heads
   For studs that backed out intact, use vice grips or stud extractor to remove completely. For broken studs, center punch the stud center and drill pilot hole using cobalt bit, starting small (3mm) and progressively sizing up. Use left-hand drill bits which may extract stud during drilling. If drilling required, use screw extractor or easy-out to remove stud remnants. Work carefully to avoid damaging aluminum cylinder head threads.
   ⚠️Metal shavings entering cylinder head ports or combustion chamber will cause catastrophic engine damage. Vacuum constantly and use grease on drill bit to capture shavings.
   ⚠Drilling off-center will damage threads beyond repair. Take time to properly center punch and verify drill alignment.
7. 7

   Clean and chase cylinder head threads
   Thoroughly vacuum all stud holes and surrounding cylinder head surface. Use appropriate tap to chase all stud hole threads in cylinder head, both for damaged holes and intact holes. Run tap in and out multiple times, cleaning tap frequently. Apply compressed air to blow out debris (while covering nearby ports). Inspect threads with flashlight for damage. If threads severely damaged, consult machine shop for helicoil insert installation.
   ℹ️Maserati cylinder heads use metric fine-thread studs. Verify exact thread pitch before chasing to avoid cross-threading.
8. 8

   Install new exhaust manifold studs
   Apply thin coat of anti-seize to first 2-3 threads only of new studs. Thread studs into cylinder head by hand, ensuring they thread smoothly without resistance. Use double-nut method or stud installation tool to seat studs fully. Studs should extend equal distance from head surface. Install all studs for both banks. Allow anti-seize to set for 30 minutes before proceeding.
   ⚠Do not apply excessive torque when installing studs. They should thread in with moderate hand pressure. Forcing indicates cross-threading.
9. 9

   Prepare and install exhaust manifolds
   Clean all gasket surfaces on manifolds using plastic scraper and wire brush. Inspect manifolds for cracks, particularly around stud holes and ports. Position new gaskets on cylinder heads, ensuring alignment with all ports. Carefully position right bank manifold onto studs and gasket. Start all manifold nuts by hand. Repeat for left bank.
   ℹ️Manifold gaskets may have orientation markings (TOP or UP). Install correctly to ensure proper sealing.
10. 10

    Torque exhaust manifold nuts
    Apply anti-seize to threads of manifold nuts. Using torque wrench, tighten manifold nuts in spiral pattern from center outward in three stages: first to 12 Nm, second to 25 Nm, final to specification. Repeat pattern for both banks. Allow assembly to settle for 15 minutes, then perform final verification pass at full torque specification.
    Torque spec

    Manifold Nuts35 Nm (26 lb-ft)
11. 11

    Reinstall turbochargers
    Install new turbo-to-manifold gaskets on manifold flanges. Position right bank turbocharger onto manifold studs/bolt holes. Apply anti-seize to exhaust flange bolt threads and start all bolts by hand. Torque to specification in cross pattern. Repeat for left bank turbocharger. Verify turbos are secure and properly seated.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
12. 12

    Reconnect turbocharger oil and coolant lines
    Install new sealing washers on oil feed and return fittings. Reconnect oil feed line to top of turbocharger and oil return to bottom, torquing to specification per service manual. Reconnect coolant inlet and outlet lines with new O-rings. Verify all connections are secure and properly routed without interference. Repeat for both banks.
    ℹ️Oil return lines must have slight downward angle to drain properly. Verify routing matches original configuration.
13. 13

    Install downpipes and heat shields
    Position new flange gaskets between turbo outlets and downpipes. Raise downpipes into position and apply anti-seize to flange bolt threads. Install and torque flange bolts to specification. Install exhaust hanger bolts and torque. Position heat shields around manifolds and turbos, install shield bolts and torque to specification.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)

    Hanger Bolts22 Nm (16 lb-ft)

    Heat Shield Bolts10 Nm (7 lb-ft)
14. 14

    Reinstall oxygen sensors
    Apply anti-seize to oxygen sensor threads only, keeping compound away from sensor element. Thread sensors into manifolds and downpipes by hand to prevent cross-threading. Torque to specification using oxygen sensor socket. Reconnect all four oxygen sensor electrical connectors. Verify connectors are fully seated and locked.
    Torque spec

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

    Refill engine oil and complete reassembly
    Install new oil filter and drain plug with new crush washer. Fill engine with 5.5 quarts of Selenia Racing 10W-60 oil. Reconnect all vacuum lines, electrical connectors, and coolant lines per labels and photos. Reinstall intake plenum and engine cover. Reinstall undertray and side panels. Reconnect battery negative terminal.
    ℹ️Do not start engine yet. Complete verification procedures first to check for leaks and proper installation.

Reassembly

1. Double-check all electrical connectors to oxygen sensors and other components are fully seated
2. Verify all coolant lines are connected and clamps tightened
3. Confirm all vacuum lines are properly routed and connected
4. Ensure no tools or parts remain in engine bay
5. Verify engine oil level is correct on dipstick

Verification

• With engine cold, start engine and allow to idle. Listen for exhaust leaks at manifold gaskets and turbo connections
• Monitor for any oil leaks at turbocharger oil feed and return lines during first 5 minutes of operation
• Check coolant level and top off if necessary after engine reaches operating temperature
• Using scan tool, verify all oxygen sensors are reporting properly with no codes
• Perform test drive at varying loads, listening for exhaust leaks or unusual turbocharger noises
• After first 50 miles of driving, re-inspect all manifold nuts and flange bolts for proper torque retention
• Check engine oil level after test drive and verify no consumption or leaks at turbo connections
• Verify no exhaust odors in cabin and proper turbocharger boost response

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