CUMMINS 4089976 GENUINE PISTON & RING KIT (.020 OVERSIZE) - OEM FOR 2003-2004 5.9L CUMMINS

The Cummins 4089976 Genuine Piston and Ring Kit (.020" Oversize) is an OEM factory solution for rebuilding 5.9L Cummins common rail engines that require oversized pistons due to cylinder wear or damage. This kit restores original compression and reliability while ensuring perfect compatibility with factory engine components.

Manufactured from high-strength aluminum alloy and matched with precision-fit piston rings, this kit is ideal for stock and towing applications.

Features & Benefits

• OEM Precision: Built to Cummins standards for fit and longevity.
• Oversize Bore: Designed for cylinders that have been bored .020" over standard size.
• Complete Kit: Includes piston, wrist pin, retaining clips, and ring set.

Cross Reference Part Numbers

• Cummins 4089976
• Replaces: 4089402, 4089975
• Interstate McBee M-4089976

Frequently Asked Questions

When should I use an oversize piston kit?

Use this kit if your engine block has been bored .020" oversize to repair worn or damaged cylinders.

Is honing required before installation?

Yes. Proper honing ensures correct ring seating and long-term sealing.

Can this be used in performance builds?

Yes, but for extreme boost levels, forged aftermarket pistons may be recommended.

Related Piston & Ring Kits for 2003-2004 5.9L Cummins

• Cummins 4089950 Genuine Piston & Ring Kit (STD) - OEM - Standard size for cylinders within factory spec.
• Cummins 4089976 Genuine Piston & Ring Kit (.020 Oversize) - OEM - For cylinders bored .020" oversize.
• Cummins 4089977 Genuine Piston & Ring Kit (.040 Oversize) - OEM - For cylinders bored .040" oversize.