Usage:
3406 Truck Engines
Description of Change: A new piston group is now used in the connecting rod and piston group on 3406 Truck Engines. The new group has a new piston body and a new "top" piston ring. The new piston ring is thicker and has a plasma layer on the outside diameter. These changes make the ring stronger and give better resistance to scuffing. The new piston ring is 3.84 mm (.151") thick in comparison to the former piston ring which is 3.05 mm (.120") thick. See the illustration. The new piston body has a wider "top" ring groove for use with the new piston ring.
Adaptable As: The new parts are direct replacements for the former parts when used together in this application. Both the new and former pistons and rings have a "Keystone" design. The parts are in effect on 3406 Truck Engines with Serial Number 92U55996. The new parts are adaptable to 3406 Truck Engines (92U28617-Up).
Formerly, a 1W8900 "Top" Piston Ring and a 1W8901 Piston Body Assembly were available for parts service. This ring and piston were the thicker design and were the same as the new parts. These former parts have been canceled because of the use of the new ring and piston at the factory.
It is our recommendation to install six new pistons and rings if you have a broken top piston ring. The former ring and piston that were used at the factory can still be used for parts service, if desired.
Cross section of piston ring.