Sherwood dry bleed contaminated piston

[fmerkel]

Opened up my wife's Oasis pony rig. It's been sitting a long time so don't remember it's history for sure. Nasty inside, obvious saltwater incursion somehow. Cleaned it up, no new parts, assembled, IP adjusts and locks up fine and breathes sweet.
Test dunk for leaks > no dry bleed....none.
A bit of research and I may be part of the problem as I put the piston along with all the rest of the metal parts in a vinegar ultrasonic bath. Nice and shiny but probably contaminated with the silicone lube residue, or the saltwater, or who knows?

This is what I've tried so far:
1. New soft toothbrush, scrub with straight Simple Green. Rinse.
2. Ultrasonic with diluted ultrasonic green (ultrasonic scrubbed 2x with simple green before being used. Rinse. Piston feels squeaky clean to feel.
3. Ultrasonic with fresh water. Rinse. Blow dry well.
Dry bleed is now ~ 5-10 BB sized bubbles/minute, no where near the spec of 13-27cc/minute
Bench test of function is great.

How do I clean that piston port? Seems silicon contamination is not easy to remove.

Addendum: Overnight soak in common rubbing alcohol (isopropyl 70%). Rinse, dry, assemble.
No improvement at all.

Now have it in a clean glass soaking in acetone, the whole thing in a warm ultrasonic bath of water.
----Well, that didn't work either.

MEK next? Other options?

 

[KeithG]

Boiling it does not work either.

One of our regs was totaly screwed up by our LDS (they fully packed it with lube).

My ultimate solution was to buy a used $40 first stage on ebay.

I claim if you are getting "some" bubbles then you are fine. As long as there is some positive pressure it will prevent water from entering the chamber via the bleed valve.

Your cleaning did not break it. Salt water incursion means it was broken before (unless the salt came from the tank side, then maybe you broke it). Salt in the chamber means piston will be screwed.

Worst case the reg will work fine even if it does not bleed. You will just need to clean it often.

 

[keyshunter]

I assume that you have an older Sherwood first stage with the dry bleed orifice and scintered filter in the piston. These filters have defied all sorts of cleaning that I have tried. The best solution is to find a new piston. A used first stage from ebay might have the same problem that you are trying to solve. I believe that this issue was the reason that Sherwood went (in the 90's) to a round first stage with a replaceable dry bleed and filter mounted in the body instead of the piston.

 

[fmerkel]

Boiling, why didn't I think of boiling.

Yes, it's an old reg, first one my wife bought back in 95'. It starved her for air on an 85' deep dive in current once and was replaced by a ScubaPro MK14....which I use now (she got a deal on a used MK20 from a known source). We converted it to a pony rig, but we're both small, rarely carried the pony so it has mostly just sat for 15+ years. No salt from a tank for sure, and that was before I started overhauling our regs. I wonder now if the reg was messed up way back then.

Been overhauling our main regs and decided to look at that one just in case we did want to use it. Insides were kind of a shock. Not having read through the manual (it's a pretty simple reg to overhaul) and not knowing the cautions about the dry-bleed I just threw the (salt coated) piston the ultrasonic with everything else. I can definitely see some issues with that dry-bleed.

 

[KeithG]

was the pony bottle first stage always pressurized when you took it under? i doubt the rubber bleed valve plug thingy would keep salt water out at depth. it is totally fine for the rinse tank.

 

[KeithG]

p.s. all 3 of the used first stages i bought on ebay worked properly. they were bought from a reseller of scuba regs that inspects them before hand.

if you have any concerns ask the seller if the reg works properly and specifically refer to the piston. if they do not know, then the answer may be no. if they say yes and it does not, then ebay will give you your money back.

 

[grf88]

Sherwood Scuba Regulator HP First Stage Piston Part Dive 3107-10

 

[redacted]

I have no experience with sherwood. Would it be possible to reliably plug up the piston bleed hole and open up the ambient chamber hole?

 

[fmerkel]

giffenk - Don't know, been too long. Back then I would probably have turned it on because the way the pony is rigged it would be about impossible to turn it on during the dive (back mount, pony holder, valve up). OTOH, it WAS a long time ago.

Note - I tried boiling. Didn't work. You said it wouldn't but someone in the Sherwood forum said they had luck with it. No harm in trying. Oh well.

grf88 - Thanks. It's an option if i really want to put this reg back to work.

awap - The piston bleed is the passage to the ambient chamber. It's small, like ball point pen refill size and at an angle. You could simply pull the plug and make it open to water to act like a regular piston but you would need to take it apart to clean it out every time. No way to flush or rinse it. I suppose on some models you might be able to simply drill holes and do the same thing but the piston is shorter than Scubapro and the ambient chamber is smaller. Probably not practical. Certainly would be a kludge work around.
****
Hours long soak in MEK make no improvement at all.

New approach - I'm taking a small diamond bit in a Dremel to the bleed plug. Take off a little and test it. Getting pretty good at taking the thing apart and assembling again. Last try I got 10cc! Almost up to spec.
I figure, what the hell, got nothing to lose.

Too bad you just can't make a hole the size of a hair. Much simpler, should do the same job. That piston plug is a serious practical weakness, even if a clever engineer concept.

 

[abnfrog]

just remove the dry bleed plug and replace it you probably wrecked it. now you used mek , its supposed to be pliable NOT hard I suspect its hard before you started (that's what we were taught in our repair course years ago to check )