Cummins ISX Inframe Technical Bulletin

There have been several updates to the components in the ISX15 / QSX15 engines since they were original introduced. Making sure you use compatible designed components in your build is critical to the service life of this engine.

All Pistons within the engine must be of the exact same design style. You cannot mix open skirt, closed skirt and 2 piece articulated pistons in the same engine. Also, all pistons must be installed facing the correct direction. Failure to align the deep valve pocket and the piston skirt cooling notch correct will result in extensive engine damage.

Engines produced before 2003 were built using 2 piece articulating pistons and traditional-type, solid beam connecting rods.

Engines produced during or after 2003 were built using upgraded, single piece open or closed skirt pistons and "Rifle Drilled" connecting rods.

Rifle Drilled Connecting rods have an oil hole drilled all the way along the inside of the shaft. This oil hole allows oil to flow to the piston pin connection.

Earlier engines can be upgraded to the newer, single piece piston design, but you MUST USE RIFLE DRILLED CONNECTING RODS when installing single piece pistons. Non-drilled rods will not provide sufficient lubrication to the piston pin and can/will result in engine damage and/or failure. Rifle Drilled connecting rods for this application can be viewed / purchased here.

For all types of pistons within this platform, the manufacturer recommends a heavy film of 85w-140 gear oil with an EP (Extreme Protection) additive be applied to three specific areas during initial installation. Failure to lubricate the piston pin bore, piston pin and pin bushing inside the rod properly can result in engine damage and/or failure.

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