vacuum gauge not returning to zero

tchicken

Registered User
I was working on an SC today after a long winter hibernation, and noticed it is running a little rough. Idle rpm changing occasionally for no reason, and it is making a humming sound that changes in pitch with the idle rpms. Only pulling about 11" of vacuum, so I figure I've developed a vacuum leak. But now I notice the needle on the gauge isn't returning to zero when I shut the car off - it still reads 2-3 psi boost after two hours. Now it has been a few months since I've driven an SC due to the weather, but I could swear that isn't normal. Anyone else have a gauge that won't zero out? Any ideas on fixing the gauge?

Horn

update: More forum searching led to a poster who previously pulled the plastic cover, pulled the needle and put it back on to show "0" when car was off. I successfully tried this same approach yesterday. Be careful pulling the pointer, as the brass-looking stem the pointer sits on is easily bent during removal. As for what caused the gauge to start reading off in the first place . . . ?
 
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If driving it more and thereby exercising it and drying it out don't improve things, you may need to replace it.
 
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