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Compressor Drain leaking air

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  • Compressor Drain leaking air

    I've got a 33 gal, 6 HP Craftsmen Air Compressor. The drain on the bottom was a bit rusty and hard to turn. I sprayed PB Blaster (I think) on the threads. Wiped the excess off with a rag after a minute of soaking. It was much easier to open/close the drain. But now it leaks air and won't get above 45-50 psi. I don't know if I damaged a seal/gasket with the spray. Or if rust is just blocking the valve from shutting all the way. I've been just finger tightening/opening it. Do I need to put some channel locks to it? Anyways, any help would be great.

  • #2
    Re: Compressor Drain leaking air

    I'd replace it. To make draining the compressor easier in the future replace the cheap OEM drain with a street elbow and a length of pipe nipple long enough to almost reach front of the tank. Then, mount a ball valve on the end of the nipple. No more getting on your hands and knees to fiddle with that old hard to get at drain valve. Just bend over, open the lever on the ball valve and drain the air and condensation right out.
    Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian."
    ------- Henry Ford


    • #3
      Re: Compressor Drain leaking air

      I do not know about that model but most are just 1/4 pipe thread, that the drain screws into, that I have seen, in my instance most of my compressors came with a pipe plug in the tanks, and I replaced it with the radiator drain which has the little handle and screws into the tank and passes the air through the center of it,

      it could be that a flake of rust has got between the closing surfaces, could try to turn the compressor on side and open it or remove it and see if there is damage,

      below are some pictures of the drain I am guessing it is (they are of the type I put on my compressors over the years)

      there is of the rear the open position and a side view,

      I would think if it is not sealing then something is keeping it from closing fully,

      at a auto parts place there reasonable low cost, under a few dollars the way I remember it, I have not bought any for some time.

      on my stationary air compressor, I did what was suggested above with the elbow and extension and ball valve,
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      • #4
        Re: Compressor Drain leaking air

        Do just what badgerdave said, you will not regret it. More than likely there is a small piece of crud suck in the elcheapo drain valve. If you do repipe it be sure to use a ball valve, a globe will be more likely to catch debris and clog. With the valve at the front of the compressor you will also drain the tank more often.

        Just be sure to relieve all of the air before pulling the drain valve out.



        • #5
          Re: Compressor Drain leaking air

          I concur, use a ball valve I have a 60 gallon tank and the stock drain valve is just awful!
          I added a right angle and a small length of pipe then a ball valve. I did use plastic tubing to extend the end so I avoid tripping over the pipe.

          To drain I simply place a rag over the plastic tube open the ball valve for a few seconds or until only air is coming out.

          I have had this configuration now over 9 years and never any issues

          Badger Dave is right on

          Cactus Man


          • #6
            Re: Compressor Drain leaking air

            Wow, thanks for the quick response. I definitely wanna install easier to use drain, cause I hate laying on the ground and trying to turn that rusty valve. Love the idea of an easier to use valve. Thanks again.


            • #7
              Re: Compressor Drain leaking air

              If it's the same 33-gal Craftsman that I have (2005), the drain valve isn't nearly as good as that pictured by BHD. On mine, it was barely a knurled knob about 1/2" in diameter. Basically just a threaded piece of brass bar that has an o-ring seal and a T-shaped passageway for drainage.

              On mine, the tank is made by DeVilbiss, (USA made), and has substantial pipe plugs for each area where the check valve, pressure switch, and drain valve are all fitted.

              Installing a fitting and drain tube to bring a drain valve off to the side is very do-able and would/should provide for a less corrosive area for most operating sequence condensation to sit, rather than at the base of the steel tank. (Providing you don't let the few drops to accumulate into larger volume.)

              I wouldn't pipe it directly out to the front however, as it may interfere with the movement of the tank, as you pull it back in that direction (tip it) in order to wheel it around (if you actually do that on occasion).



              • #8
                Re: Compressor Drain leaking air

                If you want to keep it simple, just replace the drain valve with one like BHD shows and use small pliers to gently tighten it a bit more than just finger tight. I recommend some Teflon tape on the threads and be ready to cut it down to about 3/8" width so as not to get into the wrong places as you only want it on the threads. A tiny bit of pipe dope should work too.

                What BadgerDave posted is great for stationary air compressors, but as CWS warns, you need to be careful doing that on a wheeled tank.


                • #9
                  Re: Compressor Drain leaking air

                  I put a ball valve on my portable right after I bought it. Used an elbow and short nipple so it is tucked underneath out of the way. I usually use my toe to kick it open and closed. I like to drain it and leave the valve open whenever I am done using it so there will be less moisture in the tank to rust.