ARP 900-0400 4.040 Tapered Ring Compressor | 1989-2007 Dodge RAM 2500/3500 5.9L Cummins

Features:

• CNC-machined from 6061-T6 billet aluminum
• Designed for 4.040-inch cylinder bore size
• True-radius taper ensures smooth piston install
• Compatible with 5.9L Cummins 1989–2007 engines
• Features relief for wire O-ring clearance
• Durable Type 3 hard anodized coating
• Engraved with large bore size identification
• Easy to use for quick, precise installation
• Preferred by professional engine builders
• Superior to standard tapered ring compressors
• Works with standard and metric piston rings
• Precision fit reduces ring damage risk

Make Piston Installs Smooth Every Single Time

If you’ve ever fought with stubborn piston rings during a build, you know how frustrating it can be. The ARP 900-0400 4.040 Tapered Ring Compressor makes that struggle a thing of the past. Designed specifically for precision and ease, this tool helps drop pistons smoothly into place with minimal effort and no ring damage. Whether you're building a fresh 5.9L Cummins or refreshing an old workhorse from the 1989–2007 RAM 2500 or 3500 lineup, this compressor adds confidence to every step. It’s machined from billet 6061-T6 aluminum and finished with a durable hard anodized coating, so it’s built to last through countless builds. The true-radius taper is what really makes the difference, it glides the piston into the bore with a fit that feels factory clean. You’ll appreciate how quickly and consistently it performs, especially when you’re juggling multiple cylinders in one session. If you want professional results without the hassle, this is the kind of tool that earns a permanent spot in your kit.

Engineered For Precision With Every Cylinder Drop

The ARP 900-0400 ring compressor is a high-performance engine tool designed to streamline piston installation in 4.040-inch bore engines. Specifically tailored for 1989–2007 Dodge RAM 2500 and 3500 trucks running the 5.9L Cummins, it’s CNC-machined from high-strength 6061-T6 billet aluminum. This compressor features a true-radius taper, which aligns perfectly with the cylinder wall to compress piston rings evenly and avoid snagging or distortion during installation. A key detail is the internal relief at the base, which provides clearance for wire O-rings, something conventional tapered sleeves often overlook. The outer surface is treated with Type 3 hard anodizing, increasing its resistance to wear and extending its service life through multiple engine builds. Each tool is marked with large, easy-to-read size engravings to eliminate guesswork during fast-paced assembly. Its professional-grade build quality and smart design have made it a go-to among engine builders who value speed, precision, and long-term durability.

Fits: 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 Dodge RAM 2500/3500 5.9L Cummins

Notes:

• Designed for 4.040-inch bore piston applications
• Specifically fits 1989–2007 5.9L Cummins engines
• Made from CNC-machined 6061-T6 billet aluminum
• True-radius design ensures smooth piston installation
• Relieved at the base to clear wire O-rings
• Hard anodized (Type 3) for long service life
• Large engraved sizing makes identification easy
• Widely used by professional engine builders
• More precise than standard tapered compressors
• Compatible with both standard and metric piston rings
• Ideal for serious rebuilders and performance applications