Diesel Engine Brake Vacuum Pump: Inspection

Separate center plate and vacuum pump housing. Disconnect check valve assembly. Clean all parts and check for wear or scratches on mating surfaces of rotor-to-pump housing and rotor-to-center plate. Replace any worn components. See Fig 1 .

Fig 1: Exploded View of Diesel Engine Vacuum Pump Replace all "O" rings and any pump vanes that are worn beyond specifications.
Check for wear and scratches on pump vanes. Standard vane length is .512-.551" (13-14 mm). Replace as necessary. Check inner wall of pump housing for wear. Standard pump housing inner diameter is 2.244-2.248" (57.00-57.10 mm). Check rotor shaft opening and serrated end of rotor shaft for wear.
Inspect check valve locations and copper washers for bending or deformity. Replace components as necessary. Check for air leaks and proper operation of check valves. Replace as necessary. Remove and discard all rubber "O" rings.