Used to remove carbon build-up from the glow plug bore on 6.6L diesel engines. A light coat of grease is placed in the flutes of GM-52074, which is installed into the bore in place of the glow plug. GM-52074 is turned with a ratchet BY HAND (no air ratchets) to remove carbon build-up, which, if left, could damage the new glow plug tip.
For 2016 and older Duramax engines, please see tool GM-51249.