Disco Leaks

[Dbez1]

What do you experienced airgunners use on the threads?  Teflon tape, thread paste?  Thanks.

[JustinB]

Which threads? I torn mine down all the way without needing any.

[Dbez1]

Which threads? I torn mine down all the way without needing any.

Fill valve and pressure gauge.

[JustinB]

Someone else will need to chim in on that.

[stanley1131]

Shouldn't need anything.. just replace the o-rings, I recommend 90 duro urethane.

[Schmeddz1]

I have rebuilt my Disco with an o-ring kit from ^&$@_=s. (Worth the 11 buck or so to save time looking for O-rings) The entire pressure vessel is sealed by O-rings. You do NOT need to put tape on threads. In fact that defeats the purpose if you do.
HOWEVER.. the one exception is the threads on the pressure gauge itself do not have an o-ring. Therefore one layer of tape and NO more than two layers. Some think more tape is better. Not true. That 1/8 inch fitting is tapered. You need the strong mechanical connection of the steel/brass threads on steel threads. Too much tape interferes with the mechanical bond of the threads. It should only seal the air in the thread.
I'm sure there is more info than you needed.
Also... Teflon tape leaves bits and pieces of itself that have a nasty habit of getting into orifices and things internally after disassembly. That tends to mess up small holes that air needs to flow through for good operations. '

Side note after I rebuilt my Disco it leaked around the plug receiver side o-ring where the air guage goes. (Called the gauge port part #1761-016) ^&$@_=s sells a little machined device that helps you install the gauge port into the cylinder without buggering up the o-ring when pushing the port back into place past the hole where the gauge goes through the cylinder wall.

Ok now I've posted enough. I hope.

[Dbez1]

Which threads? I torn mine down all the way without needing any.

I took the fill valve apart and there appeared to be black teflon tape (or some other similar material) from the factory.  I put thread sealer on it and reassembled.  It leaks less, but still leaks.  Are you saying I should clean those threads off and put it back togeather without anything?  Thanks to all for your help.  It's my first PCP and I'm a little over-cautious about messing with it.

[Schmeddz1]

The o- ring is the primary seal and there should be no teflon tape on the threads for the fill valve assembly. The pressure of most HPA assemblies is designed to work with the pressure pushing the o ring into the gap for sealing. Teflon tape will interfere with that by being a contaminate. If the faces of the metal are pitted from any moisture the o ring will not work. The metal must be clean and free of those types of contaminates as well. If I remember correctly there are two pressure o rings. There should be no tape on those threads. If the two Orin's are failing, it could be because the threads inside the pressure cylinder could bugger up the o rings on the installation of the plug. You might also check the fill valve for proper seating. Where is the air leaking?

[gnef]

I will have to disagree, I believe the OP is referring to the male foster fitting inside of the entire fill assembly on the end of the tube. The entire assembly uses o-rings, so no tape is necessary, but the foster fitting inside of it should use tape or sealer. I personally use tape as that is what I have on hand, and I have always used three layers. Mine has been leak free for a while now. My first leak was the check valve inside the foster fitting, and my second leak was at the gauge block. Make sure to use the correct silicone lube on any o-rings, and not any petroleum based products!

[Schmeddz1]

I actually don't think we are disagreeing where to use the tape. I was not being specific enough. The foster fitting nipple will have tape on the threads. Any valve seat that opens and closes under pressure or during any operation of opening and closing in the pressure vessel should never have tape. Anywhere you see an o-ring as the sealing device should never have tape. Tape will always interfere with the designed operation of the o-ring to metal interface.

As Always... My main concern is always safety first, then the leaks. BE Safe!