In article ,
Bob Engelhardt wrote:

I have an IR home-shop compressor (20 gal, 1 1/2 hp) with a leak. I
just measured & timed it: in 17 hours the pressure dropped from 100 psi
to 55. This means the compressor runs several times a day just to
maintain pressure. It is loud, so this is annoying.

If my ballpark calculations are correct, you're losing 3.7 gallons of
air (at atmospheric) per hour, so you should be able to see bubbles when
you hit it, unless it's distributed over a lot of joints, each leaking a
little bit.

You can add a bit of glycerine to the soapy water to help the bubbles
last longer, but generally soapy water (and good lighting) does the
trick. Does this thing have piping connected to it? Have you checked all
that? If it has an airhose attached and pressurized, drop the hose in a
bucket of water and look for bubbles.

Other option is just to turn it off when you are not using it.

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