Underdrive Piston – Mopar (4431611)

Underdrive Piston is a reciprocating component that seals the combustion chamber. Clearance and surface finish decide whether it seals correctly, so the bore has to be measured before a replacement is chosen.

Replace the Underdrive Piston when a leak-down test shows air escaping past the rings, when the skirt is scuffed, or when ring lands are cracked. Check the ring end gap in the bore it will run in.

This Underdrive Piston is listed as part 4431611 (Pistons, Rings & Cylinders). Where a number has been superseded, the current reference is the one that ships, so check any supersession note before ordering.

The stock here is genuine MOPAR, and this Underdrive Piston keeps the original engineering number, which matters once a number has been superseded more than once.