Ok , so my brake vacuum pump on the 01 s40 was making alot of noise, I disconnected it til i could get another one from junkyard. I plugged in the power to the new one and it still makes alot of noise, I didn't plug the hose though. My question is, if there is a leak will it make noise. Maybe my original pump is goo and there is a leak somewhere?

 

I played around with the pump, I plugged the power and blocked the tube. The noise was alot less, how much noise are these pumps supose to make? I dont remember my original one making a loud whining noise until I noticed it. Is it possible that one of the tubes on my original one is leaking? How can I test a vacuum leak?

 

You get a mechanics stethoscope from Harbor Freight and go searching. �� There are other more serious methods like a smoke maker with a UV light and special glasses. Pump the smoke in and look for the leaks.

The cheapest, fastest method is a rubber hose placed against your ear on one end while the other is moved around the engine bay listening for that hiss.