1st Stage Hiss...

[Couv]

That throws new light on the subject. I am assuming the nick is on the mating surface of the yoke nut where it seals against the tank o-ring. As you pointed out, it is noticeable probably to the naked eye. Most significant surfaces are examined with a 10x magnifying glass for defects. Next, if the nick is such that it damages the o-ring, then you will be changing o-ring after each use. If you are good at such things, you could polish out the nick, but if you do not feel comfortable with that, invest the money to have piece of mind. At any rate, do not leave it as it is.

c

 

[redacted]

A little o-ring extrusion should fill in the scratches and imperfections (the kind that can be seen but not felt) in the mating surface of the yoke nut. One thing you might try is replacing the tank o-ring making sure to use a duro 70 replacement. If that works, it is a $.10 solution. If the knick is large enough that you can feel it, a little smoothing or replacement may be required.

 

[weaserm99]

I work on delta 4s all the time with the dvt, the hiss is most likely the dvt, i find that when you turn a tank on very slowly it seems to make a hissing sound. If i turn on the tank a little faster i dont seem to realize a hissing noise.