Information on Correct Piston Usage

This bulletin is being revised to update the Parts Information. Please discard Corporate Bulletin Number 03-06-01-028 (Section 06 - Engine/Propulsion System).

Should any of the above vehicles require a piston for any reason, the following replacement part number should be used.

12585784 - Standard size piston with piston pin, rod and rings

Although this replacement piston may not appear to match the piston that is removed, it has been designed to replace all 2002 and 2003 model year engine pistons. This change was implemented into production engines beginning with EUN (engine unit number): V301290522. The EUN may be found on the left side of the engine under the A/C compressor bracket or at the rear on the back of the cam cover.

Important: When replacing pistons, all six pistons must be replaced if the EUN is below the above number or if the EUN cannot be located. If pistons of different types were installed in the engine, excessive engine vibration would result.

Piston rings for these engines will not be released and will require a piston change if a piston ring change is indicated.

Parts are currently available from GMSPO.