sanborn air compressor goes to pressure 135 lb and then bleeds air to 80 and starts all over again

air compressor goes to pressure then bleeds air for some type of safety valve to lower pressure and starts over

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Bill says...

Bleeding from where? If from the UNLOADER VALVE then have a read of the page on CHECK VALVES.

I suspect, based on what you've written, that a leaking check valve is your compressor problem.

Cheers,

Bill