# Vacuum Pump -> purpose ?



## jlw (Sep 18, 2010)

I've been running without mine for a few days now (removed the push rod) because it was making bad knocking sound, and I notice no difference on how it runs, nor can I logically figure out why its there.. 

Anyone know?


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## s-rocc (Nov 27, 2001)

Audi seemed to love redundancy? I'm guessing they were concerned that there were too many vacuum operated mechanisms for the engine's vacuum alone, presumably only at idle.

I had the pushrod removed from my 4kq for the same reason. It wears ever so slightly after 100s of thousands of miles, and ends up a bit to short, which causes it to make that tapping noise. I never noticed any ill effects, the engine builds plenty of vacuum to operate the brake booster, climate controls, cruise control and the diff locks on awd cars.


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## AudiSportA4 (Mar 3, 2002)

Some extreme braking can require the extra boost, but I have never heard of any instance it mattered. I've owned and worked on a number of I-5s. Tossing that pos is the best thing you can do.


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