6.7L Dodge 1989-2007 3920691 Retaining Circlip for Euro 3 6.7 liter Cummins ISB/QSB engines

The 3920691 Retaining Circlip is a Cummins part primarily designed for Euro 3-compliant 6.7L Cummins ISB/QSB engines, but it is not compatible with 5.9L Dodge engines (1989–2007). Here’s why:

Key Differences: 5.9L vs. 6.7L Circlips

1. Diameter & Fitment:

   • 3920691 is sized for 6.7L piston pins (32mm).

   • 5.9L (12V/24V) engines use smaller circlips (typically for 25.4mm or 29mm pins, depending on year).

2. Euro 3 Specifics:

   • The 3920691 clip is hardened for high-pressure Euro 3 engines (emissions-compliant), which have different piston/wrist pin tolerances than older 5.9L engines.

3. Risks of Misuse:

   • Installing a 6.7L circlip in a 5.9L engine could lead to:

     • Clip failure (due to incorrect tension)

     • Piston pin walk (catastrophic engine damage)

Correct Circlip for 5.9L Dodge/Cummins (1989–2007)

Critical Notes

⚠ Never interchange circlips between 5.9L and 6.7L engines—even if they appear similar.
⚠ Always use matched sets (circlips are sold in pairs for each piston).

Need help finding the right circlip for your 5.9L? Reply with your engine’s serial number or build date!