What is this washer?

[Rawze]

Looks like the injector cam retainer/taper compression plate. It is common for mechanics to over-torque it because it is well known for the injector cam to slip if the gear is not installed exactly to procedure.


It is the one on the top right..


using an air tool on it will crack it like that too. Cummins has had an updated retaining plate that is much thicker to replace the older style that cracked on your friends truck. The old style retaining plate in the picture you provided should not be used or re-installed if someone takes one off.