Leaking Stem on US Divers K Valve

[agdobson]

I took my cylinders in for visuals and the dive shop reported that when re-filling, air was leaking around the stem and handle of the shown US Divers K valve. They gave it back to me more or less in pieces, so I am not sure if there were more washers and O-rings when I gave it to them. The J valve below it is fine.

I have looked at the excellent Power Point in the manuals area, but since my valves are newer (early 80s, I think, with left-hand threaded bonnets and plastic handles) there may be some differences. I would appreciate any help from those familiar with the newer versions of these valves.

The diagram in the power point shows only one washer (Part 0502-08) on the stem and no o-ring on the bonnet, but my J valve had an o-ring on the bonnet and the 1975 Aqualung catalog says on page 13: "This year's revised bonnet includes O ring and backup ring sealing mechanism to insure absolute reliability at high pressure." There was no O ring on the K valve's bonnet when it was returned from the dive shop, but the bonnet and valve body appear to be machined to accommodate the O ring, so I have put one on. My J valve has two washers on the stem: a thin, slightly larger diameter one and a second thicker, smaller diameter one. Both fit snugly on the stem shaft. The K valve came back with the one, thin , small diameter washer that is fairly loose on the stem shaft. There is no copper crush washer on either valve (nor do I believe there should be).

I am thinking that the best solution would be to make the K valve the same as the J valve. That is, an O ring under the bonnet and a thin and thick washer on the stem. Any comments?

I am guessing that the O rings I need are the ones on the valve page in the store in this site described as "Thin Teflon Washer" and "Thick Teflon Washer". Does anyone have experience with these parts and can confirm they work on the US Divers valve stem?

Thanks for your experience and help.

Andy

[captain]

This is Aqua Lung's latest online valve manual and should answer any questions as what is what. I also should have most or all of the replacement parts for these valves if you need anything.

http://www.aqualung.com/militaryandprof ... _07-07.pdf

[Gilldiver]

There should be a white teflon backing ring or packing up insides of the bonnets. When the stem starts leaking it is almost always because the O-ring is shot. I am surprised that any dive shop didn't fix it on the spot after they asked if you wanted it fixed as the valve stem assembly is the same now as it was then.

[agdobson]

Thanks for the responses and accept my apologies for being so late replying- I was lucky enough to be away for the last 3 weeks and even got in some diving!

Captain:

Thanks for linking to the Aqualung valve manual. My J-valve and K-valve look exactly like the ones shown on page 10 of this manual, but as can be seen in the above photos neither are configured in the same way. Instead of the blue thrust washer, o-ring and back-up ring shown in the manual, my J valve (which does not leak) has a blue thrust washer and a thick washer. No o-ring or back-up ring. Since the K-valve leaks, the single washer on it is clearly not correct.

Interestingly, the valve rebuilding.pdf downloadable from this site shows no o-ring on either the stem or the bonnet and only a single thick looking washer on the stem. Also on page 15 of your manual, the slightly different K and Z-valves have an o-ring and packing washer on the stem, but no thrust washer. Are these just different ways of "skinning the cat" and all would be suitable? Or should I try to get the exact bits shown on page 10?

If you do have these replacement parts, I appreciate your kind offer of selling me some.

Andy

[scubasteve59]

I had the same experience on my last dive shop VIP....leaking valve that they could not fix. Fortunately, I have a box of spare valves. I think the days of true dive shops are over, perhaps I'm wrong.....and these guys want to do annual reg. inspections for me. Ha.