air compressor question
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  1. #1
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    I have a small air compressor, 2.5 hp, 8 gallon. My oil dipstick has been blowing out recently everytime the compressor kicks in. As a quick fix I was just going to tap the hole so it couldn't come out, but was wondering if the compressor should normally be building this kind of pressure or if it was a sign something else was wrong. Any insights?

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    Sounds like either the crankcase breather is clogged or the pump needs a ring job.

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    Mine did that when the vavle plate failed - you may want to check that.

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    thanks guys, I'll check these out!

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    Default Compressor: Lost all compression. Will not pump

    Greetings!
    I'm new to this forum so not even sure if I'm in the right place. Bear with me.
    Have a Quincy Compressor Model 325, Reciprocating, 2 stage, 5HP.
    Lost all compression. Will not pump.
    Thoughts?

    Thank you for ANY info you can provide.
    Paul

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    If it is running, but not pumping ANY air, I would look at un-loader, and the valves. WAG says you will need to rebuild the head, there is a pretty good video series on YT from "rotarycomptech", or something like that showing how to do it, if you are so inclined.

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    Thanks. Ironically I was just looking at that video lastnight!

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    Definately have a look at the unloader valve.
    Is it building oil pressure on the guage?

    I have a 325-7 from 1961, and its next to impossible for it to NOT make air, unless the unloader isnt functioning (oil pressure or blown o rings)

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    The big industrial-flavor Quincy pumps have more than one operational mode, and the unloader function is the key.

    They can be run in stop-start mode... where the unloader dumps head pressure after shutdown, and keeps it in relief state until the pump reaches a fairly high speed... this keeps the motor from being loaded at a slow speed. This is normally used with electric motors, and it can also be used in engine-driven applications where the unloader's pilot pressure acts upon a little air-cylinder to idle the engine down.


    They can be run in constant-speed mode... where the unloader is activated when setpoint pressure is reached... but pump keeps spinning... the pump(s) are just relieving to atmosphere... and when below the activation setpoint, the unloader releases the bypass and causes the compressor to go back to work. This is frequently used in engine-driven applications where the engine speed is not modulatable (it's powering something more important, like a synchronous generator or a traction generator, or a hydraulic power unit, or a pump).

    A compressor SYSTEM may also use BOTH modes.. like an electric motor with a starting contactor, that will start and run, charging up the tank for 5 minutes, and then shutting off for a few hours... BUT... if the motor control system detects that the motor has been cycling more than so many times in an hour, it just keeps the motor running, and operates the unloader in constant-speed-mode instead... and after demand drops off, the system returns to start/stop mode.

    IF the compressor system operated properly prior to arriving in your custody, then I'd bet my lunch ticket's day-stamp that one of the unloader tubes has become crimped-smashed-plugged, or broken, thus not operating properly.

    Compressor valves DO get dirty... and it DOES cause them to lose sealing effectiveness, but they don't all just fail at once.

    BTW, Paul- welcome to the group, and it would have been better for you to start a new thread on your Quincy 325, with that in the heading, than to tail-end onto a very old thread.


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