Accuracy in the bottom end is the key to engine longevity. Learn how to use the ATC 7900 to ensure a perfect piston seat on MX13 engines.

Why Dedicated Ring Compressors Beat Universal Tools

The PACCAR MX13 uses high-tension rings and specific liner top-chamfer angles. Universal "adjustable" band compressors often fail because they allow the ring to expand slightly before it hits the liner, leading to a "hanging" ring that snaps under the pressure of a mallet. The ATC 7900 is a solid, tapered-bore compressor that transitions the rings directly from the tool into the liner without any gap for expansion.

The 5-Step Professional Installation

1. Lube the Tool: Apply a light coat of clean engine oil to the internal taper of the ATC 7900.
2. Stagger the Rings: Ensure your ring gaps are staggered according to PACCAR service specs to prevent blow-by.
3. Position the Compressor: Seat the ATC 7900 squarely on top of the clean cylinder liner.
4. Guide the Piston: Carefully lower the piston assembly into the compressor. The weight of the piston should be supported to prevent tilting.
5. The Final Seat: With the compressor held firmly against the liner, use a wooden or plastic mallet handle to drive the piston home. If you feel sudden resistance, STOP—the tool ensures alignment, but it cannot overcome a ring that has "popped" due to improper tool seating.

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