With the pump running and warmed up, I was doing some "housekeeping" tasks, tightening the bolts on the pump and the burping noise dissappeared as I tightened the cap screws on the first stage end plate! Now the pump is quiet except for the snaping sound. This also gave me five microns at the pump throat.
Taking the pump apart was a not difficult, if you decide to try it, don't take off the end plate in the first stage, There is nothing in it but the shaft end. You can clean up the oil sump by just removing the pulley and the 1/4-20 bolts holding the rotor assembly to the case, you dont have to touch the rotors. You can replace the gasket and both shaft seals with this level of disassimbly.
Created on Tuesday, April 24, 2001 11:05 PM EDT by Thomas D Dressel