Sherwood Valve...What am I missing ?

[Bryan]

When shut off it's fine....When you open it up it leaks like a screen door on a submarine around the stem. I was thinking that years ago Sherwood used to sandwich an O-ring between the nylon packing washers but when I took this one apart these are the parts it contained.

[antique diver]

That is the latest configuration of the valve packing, as the oring was discontinued some years back... but you may be missing the copper washer that goes down into the female threaded area of the valve. It seals the edge of the threaded bonnet against the valve body. (it may still be in place down in the valve, but if not there, the lack of it is a likely cause of the leak)

There is another common cause for the leakage. I know this doesn't sound logical since teflon is supposedly self-lubricating, but this particular combination is notorious for leaking unless you use a fair amount of silicone grease on the shaft and both teflon washers. The thinner washer goes onto the shaft first. I have seen a number of these leak that just needed more grease to solve the problem... so give it a try and let us know.

[Drado]

I had a valve like that with a similar condition before. Had a small leak as well when open. Replaced the copper crush-washer between the bonnet and the valve and it was all good after that.

[Bryan]

I did both... Put in a new copper washer and packed the stem with grease....So far so good! I really appreciate the help.

[Robohips77]

Agree on copper washer. I have a valve just like, took it apart, and it has the copper washer. Is it copper or brass?

[antique diver]

Agree on copper washer. I have a valve just like, took it apart, and it has the copper washer. Is it copper or brass?

The original equipment is copper. If you need one let me know and I'll drop it in the mail. Sometimes getting the old one out is difficult, and sometimes they just drop out. Be careful not to scratch up the sealing surface below it while digging it out if it's stuck.

At times I have had to reuse one just because it wouldn't gracefully come out, and in a pinch have even dropped a new gasket over the stuck one if it wouldn't stop leaking... but that's a last resort to save a valve after trying the next suggestion:

A little silicone grease or O2 compatible lube on the bonnet threads and sealing surface that touches the copper gasket can reduce friction enough to let the bonnet tighten more and compress an old leaking gasket. That's worked for me before.

[luis]

I have used Teflon tape on the threads as a lubricant, a metal isolator, and to help is seal. The only important thing is to make sure the Teflon tape is only on the threads and not near the sealing surface of the copper washer.

I have had very good results with it and when I inspect the valves years later the Teflon tape kept any corrosion from occurring anywhere near the threads, since the tape sealed the threads from the salt water. It was also very easy to disassemble the valves.

That being said, I haven’t being using the Teflon tape recently. No particular reason… I just rebuilt them just like Sherwood recommended and haven’t had any issues. I think I used to see a lot more corrosion in the Caribbean that I do up here.

[sitkadiver]

Forgie me for resurecting an old thread...

Is the copper washer included in the valve rebuild kit in the store? I have about 4 or 5 valves that are all leaking from under the handle when the air is turned on. I suspect that many of these took a tumble on the boat and may have torques the valve stem(the part the handle attached to.)

Could copper washer bend under a load when the tanks go flying? And can I reuse the same seat over again?

[ebj]

It looks like the copper washer is included in the kits and is also available by itself.
I would try tightening the bonnet nut first. I had one sherwood valve out of four that I had just rebuilt leak like yours. Tightening the nut some more solved the problem. Apparently, some valves require a little more torque to seal properly.

[captain]

Copper is used because it is soft and compresses slightly when the bonnet nut is tightened. Brass would be too hard.