Jay,

The rotary exhauster is used to provide vacuum for vehicle brake system. This is mounted on the right side of the engine as you sit in the seat. I guess you have a Perkins engine?

Engines that are diagnosed with excessive crankcase blow-by must first have the rotary exhauster removed from the engine and the engine
run for this diagnosis to be valid. A brake booster diaphragm failure may also cause the rotary exhauster front seal to be pushed out causing
crankcase pressurization. Good Luck