CUMMINS 4089950 GENUINE PISTON & RING KIT (STD) - OEM FOR 2003-2004 5.9L CUMMINS

The Cummins 4089950 Genuine Piston and Ring Kit (Standard Size) is the OEM solution for rebuilding your 5.9L common rail Cummins engine. Designed to meet factory specifications, this kit restores proper compression, oil control, and durability in your diesel engine.

Each kit includes a matched piston and ring set manufactured from high-strength alloys for long service life in both stock and towing applications.

Features & Benefits

• OEM Quality: Genuine Cummins parts guarantee exact fit and reliable performance.
• Standard Bore Size: No machining required if cylinder walls are within service limits.
• Complete Kit: Includes piston, wrist pin, circlips, and piston ring set.

Cross Reference Part Numbers

• Cummins 4089950
• Replaces: 4089400, 4089951
• Interstate McBee M-4089950

Frequently Asked Questions

Do I need to hone the cylinders before installing?

Yes. Even with a standard-size piston, a light hone is recommended for proper ring seating.

Is this kit for one piston or a full set?

This listing is for a single piston and ring set. Order quantity based on the number of cylinders being rebuilt.

Will this work in a performance build?

Yes, but for high-boost or racing applications, consider forged aftermarket pistons.

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.

Fitment

• 2003 Dodge Ram 2500/3500 5.9L Cummins
• 2004 Dodge Ram 2500/3500 5.9L Cummins

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