On the ISX CM871 and CM2250, the flywheel housing overlaps the rear main seal housing. If you torque the flywheel housing without first ensuring the rear seal housing is perfectly flush, you will crush the seal.
Incorrect torque leads to:
Some older or specific ISX/QSX15 variants may list a final torque of 150 ft-lb (203 N•m) [4, 27]. Always verify with your specific Engine Serial Number (ESN) Cummins QuickServe Installation Procedure & Sequence Cummins Isx Flywheel Housing Torque Specs
The later ISX engines (X15 architecture) use an aluminum flywheel housing to save weight. Aluminum changes the game: On the ISX CM871 and CM2250, the flywheel
Two hollow dowels (one at 3 o’clock, one at 9 o’clock on the block face) ensure concentricity. Always verify with your specific Engine Serial Number
: Clean the mounting surfaces thoroughly. Apply a consistent, recommended bead of approved sealant to the housing's rear side.