Sihi pump leaks

[madmapler]

I used a 2 stage 7.5 hp sihi pump this year on a 2000 tap bush and could only pull about 22hg. The system is new and tight. This pump sat around a few years before being put back in use and the seals leak water pretty bad when the pump isn't running. Could this also be causing enough of a vacuum leak, if at all, to drop the pressure that much? It should be able to pull 28hgs easily. When the system was frozen up solid at the releaser I could still feel a good amount of air passing through the exhaust. I'm taking that as an indication that the pump probably does leak. Am I right or should I be looking elsewhere? Thanks.

[WMF]

MadMapler,
I think you are correct. If the pump is moving air out the exhaust it is pulling it in from somewhere unless it is very hot and is making steam from the service liquid. If the impeller clearances were too big the air bypasses them and does not come out the exhaust.

Is this a 3708 ? I have one and mine has packings on each seal end which can be tightened by two small nuts and a flange. Some had a rotary lip type seal that would have to be replaced.
I would seal up all openings on the pump and put about 20 psi of water on it and see where the water leaks out.

[madmapler]

Its a lphe 45316 but it does have the nuts and flange like yours. I tried tightening them a little but wasn't absolutely sure about what I was doing. It has a fresh cold water supply that I had to restrict because unrestricted it would draw too many amps. I balanced the flow rate with the highest vacuum level I could achieve so I guess the seals have to be it. Thanks.