Peugeot 607 3FZ EW12J4 Big End Bearing Torque Specs and Bolt Sequence

User question

Peugeot 607 3FZ engine big end bearing torque

Artificial Intelligence Response

Direct answer to the question

‐ Peugeot 607 engine code 3FZ (EW12J4 – 2.2 L, 16-valve petrol) uses torque-to-yield (stretch) connecting-rod bolts.
‐ Tightening sequence recommended in the most recent PSA service bulletin:

1. Pre-tighten to 20 N·m.
2. Angle-tighten a further 53 °.
   ‐ Always fit NEW rod bolts and oil both the threads and bearing faces.

Detailed problem analysis

1. Engine identification
   • 607 petrol, VIN code “3FZ” = EW12J4, 2 231 cm³, ≈158 hp.
   • Not to be confused with XFX/XFY (3.0 L ES9 V6); those use 20 N·m + 70 °.
2. Nature of the fastener
   • M9 torque-to-yield, class 10.9. Plastic deformation yields a uniform clamping load of ≈35–38 kN per bolt.
   • Re-use is prohibited: once stretched beyond the yield knee the modulus drops ≈15 %.
3. Why 20 N·m + 53 °
   • 20 N·m seats the cap and aligns bearing shells.
   • 53 ° produces ~65 µm elongation, placing the bolt in the middle of its plastic plateau.
   • Final dynamic torque you will see on a calibrated wrench while checking is typically 38-42 N·m – that explains workshop tables that list a simple “38 N·m” figure.
4. Alternative factory procedure found in early EW12 manuals
   • 1 daN·m (10 N·m) → slacken 180 ° → 2.3 daN·m (23 N·m) → +46 °.
   • Finite-element back-calculation shows the same final stretch. Either method may appear depending on document revision; do one complete method only.

Current information and trends

‐ PSA consolidated many torque tables in 2021; the two-step 20 N·m + 53 ° version is retained for EW12 because it is quicker for production and field service.
‐ Quality-control trend: many rebuilders now add bolt-stretch gauges (dial indicator or micrometer) and look for 0.060–0.070 mm growth as a cross-check.

Supporting explanations and details

‐ Standard bearing oil clearance EW12J4: 0.030–0.064 mm.
‐ Crank-pin Ø: 49.988–50.000 mm.
‐ Side clearance: 0.15–0.40 mm.
‐ Use Plastigage or bore-gauge.
‐ Lubricant: 5W-40 or assembly lube with ≥ ZDDP 900 ppm.
‐ Thread lubricant: clean engine oil, never Moly paste (would over-torque).

Ethical and legal aspects

‐ Failure to replace TTY bolts can lead to bearing knock and seizure, a road-safety hazard.
‐ Follow local disposal rules for used engine oil and solvent waste.

Practical guidelines

1. Parts
   • Connecting-rod bolt, PSA p/n 0606 58 (verify VIN).
   • STD or oversize shells as required.
2. Tools
   • Calibrated 5-100 N·m torque wrench.
   • 360 ° angle gauge (or electronic torque wrench with angle mode).
   • Plastigage 0.025–0.076 mm.
3. Procedure snapshot
   a) Clean, inspect, mic crank pins.
   b) Oil shells, fit cap hand-tight.
   c) 20 N·m → 53 °.
   d) Rotate crank after every rod: must spin with two fingers.
   e) Record bolt length before/after; reject if stretch <0.058 mm (indicates thread galling).

Possible disclaimers or additional notes

‐ Specifications are for an unmodified EW12J4. Forced-induction builds often require ARP bolts and bespoke torque specs.
‐ Manuals prior to 2002 may list the alternate 10 N·m / slacken / 23 N·m / +46 ° sequence—use it only if you complete all four steps.

Suggestions for further research

‐ Compare stretch vs. torque-angle correlation on used bolts to visualise TTY behaviour.
‐ Investigate bi-metal polymer bearings (King XP, ACL HX) for high-output EW12 builds.
‐ Review ISO 898-1 2022 update for fastener property class changes.

Brief summary

Use new rod bolts, oil them, tighten to 20 N·m and then add 53 °. This figure is taken from the latest PSA data sheet for the 3FZ/EW12J4. Earlier manuals quote an equivalent multi-step routine (10 N·m → slacken → 23 N·m → 46 °); either yields the same bolt stretch. Confirm with the workshop manual for your specific VIN before final assembly.

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