Peugeot 607 3FZ EW12J4 Main Bearing Torque Specs, Bolt Sequence, and TTY Procedure

User question

Main bearing torque for Peugeot 607 3FZ engine

Artificial Intelligence Response

Direct answer to the question

• Engine: Peugeot 607 – 3FZ (EW12J4, 2.2 L DOHC 16 V petrol, 1999-2009)
• Main bearing cap retaining bolts are torque-to-yield (TTY) and must be replaced at each build.
• Factory procedure (Peugeot Service Box, EW12J4 workshop manual – most recent revision):

1. Pre-tighten vertical M11 bolts to 10 N·m.
2. Tighten M6 “keeper” screws to 5 N·m.
3. Completely slacken all M11 bolts.
4. Retighten M11 bolts to 10 N·m.
5. Tighten M11 bolts to 20 N·m.
6. Angle-tighten M11 bolts a further 70° ± 5°.
7. Tighten M6 screws to 10 N·m.
   • Bed-plate / cross-bolts (M8, horizontal): 35 N·m, single stage (replace bolts).
   • Tightening sequence: start at the centre main, work symmetrically outward (3-2-4-1-5 on five-cap block).

Detailed problem analysis

1. Engine architecture
   – The EW12J4 (3FZ) is an aluminium open-deck block with an integral cast–alloy ladder frame (bed-plate).
   – Vertical M11 TTY bolts provide clamping; horizontal M8 cross-bolts add rigidity.
2. Why the multi-stage procedure?
   – Seating/pre-torque (10 N·m) aligns caps and starts bolt stretch.
   – Relaxation removes uneven friction.
   – The final torque-plus-angle phase guarantees predictable clamp load independent of thread and washer friction.
3. Torque-to-yield behaviour
   – Bolts are stretched into the plastic/elastic transition. Re-use risks inadequate clamping or bolt failure.
4. Bearing clearance check
   – Plastigage target: 0.027 - 0.051 mm for mains (Peugeot spec).
   – End-float: 0.07 - 0.27 mm (thrust on centre main).

Current information and trends

• PSA’s later EW & EC engines all migrated to torque-angle TTY on mains and big-ends; 70° superseded an older 45° angle found in early print manuals.
• Aftermarket bolt sets (e.g., ARP) available that use single-torque values (≈70 N·m) and are re-usable, popular in motorsport builds.
• Widespread use of bed-plate blocks continues in modern downsized turbo units for NVH and rigidity.

Supporting explanations and details

• Angle gauge accuracy: within ±2° for even clamping; inexpensive digital gauges simplify field work.
• Lubrication: light engine oil on threads and under-head, not Moly; PSA data assume oil.
• Sequence illustration (five-cap block):
centre (3) → 2 → 4 → 1 (front) → 5 (rear).

Ethical and legal aspects

• Failing to replace TTY bolts contravenes Peugeot repair guidance and can lead to catastrophic engine failure, a potential safety hazard.
• Always document torque values in professional workshop records for liability protection.

Practical guidelines

• Use calibrated torque wrench (±4 %) and verified angle gauge.
• Spin crank after each stage: it must rotate freely with <1 N·m break-away torque.
• Clean block threads with M11 chase tap; debris raises friction and under-torques the joint.
• If the ladder frame is removed, reseal with anaerobic flange sealant specified by PSA (Loctite 518 or 5205 equivalent).

Possible disclaimers or additional notes

• Some early EW12J4 documentation lists “20 N·m + 45°” – superseded by 70° bulletin (2003). Always confirm by engine VIN and edition of Service Box.
• Values in generic torque tables or 3.0 L ES9 (V6) data are not valid for 3FZ.

Suggestions for further research

• Compare clamp-load scatter between PSA TTY bolts and ARP reusable studs for performance builds.
• Investigate friction-modified lubricants on torque-angle correlation for aluminium ladder frames.
• Monitor introduction of stretch-bolt ultrasonic verification tools in OE plants and their aftermarket applicability.

Brief summary

For the Peugeot 607 3FZ (EW12J4) engine, renew the main-cap bolts, seat them at 10 N·m, slacken, retorque to 10 N·m then 20 N·m, and finish with +70° (±5°). Cross-bolts take 35 N·m. Follow the centre-out sequence, check crank freedom, and verify clearances. Using the correct TTY procedure is mandatory for durability and safety.

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