Annoying vacuum gremlin!
 

Alright, going to have to "ask the audience" on this one, since I *think* I know the answer, but I want to be 100% certain.

About a year ago, driving home from work one day, I lost vacuum power. Braking became a chore (not to mention dangerous), door locks eventually stopped working, A/C vents stopped operating properly, transmission clunking, engine wouldn't shut off, etc. I took it to my mechanic, who figured it was my pump going bad, or a bad check valve. He checked the pump, and it was giving 25Hg at the time, so he just replaced the check valve on the pump. Off I went on my merry way, and later that week - same thing happened.

At this point, I wanted to try MY hand at it, so I went out and bought a Mityvac. Even when the "problem" was present, my pump was giving me a strong 25Hg in vacuum, which told me that my pump was likely fine. I stuck the tester on the booster side of the main line, and I got a "wobbly" 10-15Hg of vacuum. Draining the vacuum from that side took a while for it to "recharge". At this point, I basically figured "okay, I have a bad booster vacuum line", forked over $25 and picked up a new line. I installed it, and the car worked flawlessly for well over 10 months. Well, September has started, and the problem has reared its ugly head again. Same thing as last time, 25Hg at the pump, but "flaky" performance at the booster side of the main line.

I'm guessing I got a 'dud' vacuum line, and the check valve in it is broken again. Is it possible that something inside the booster is breaking off and jamming these things, or could it just be bad luck? I'd imagine that pieces of the booster flaking off would probably present other, more obvious issues. There is no paint damage on the outside of the booster, and the booster holds vacuum just fine. I already ordered a new vacuum line, but is there anything else I should check? Is there an in-line filter I could install?

Sorry for the long post, but I figured you guys would probably want the whole story. Thanks!

Assuming you had everything hooked up when you got the 10-15 wobbely inches, you still need to check the other way and make sure all other circuits hold. You might have an intermittent leak in a connection somewhere.

Huh, odd. I was under the impression that the check-valve in the main booster line would prioritize vacuum to the booster, before providing vacuum to the other components.

Even still, what component would possibly have that large of a leak? My pump puts out 25Hg of vacuum, so there'd probably need to be a totally open connection to cause any major problem. I'm not opposed to doing a total vacuum check, but since my door locks will still work after 4+ days of non-use, I have doubts that there's any major leaking going on. =)