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Sherwood dry bleed contaminated piston

Discussion in 'Regulators' started by fmerkel, Aug 13, 2016.

  1. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
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    I'll pull mine and get a measurement on that underside relief. The picture is not good enough for that and the difference is quite small.

    Swap? Dunno...have to rummage through some stuff and see what might work for you.
     
  2. couv

    couv Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: 13th floor of the Ivory Tower
    4,669
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    Sorry about the pictures; I took them with my laptop camera-I had to crop out my ugly mug.

    Here are a few dimensions in inches.
    Spring cavity depth 0.140
    Spring cavity diameter .625
    Piston head thickness .220

    If this is what you are looking for don't sweat the trade-we'll work something out.
     
    Last edited: Oct 3, 2016
  3. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
    1,603
    586
    113
    Looks like the one. This is off my original piston:
    Spring cavity depth 0.130
    Spring cavity diameter .626
    Piston head thickness .219

    This is off an unbalanced Oasis parts reg off eBay (didn't notice that in the picture).
    Spring cavity depth 0.046
    Spring cavity diameter .630
    Piston head thickness .218

    The cavity depth is such that I can't even attempt to use the parts piston, which does work fine in the reg it came in after being cleaned up.

    PM sent for possible parts swap.
     
  4. giffenk

    giffenk Great White

    # of Dives: 500 - 999
    Location: toronto
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    2,403
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  5. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
    1,603
    586
    113
    That 3107 definitely has a shallower spring cavity. Mine looks like the 3601.

    Where do I find out for sure what model my Oasis is? There don't seem to be any identifying marks. It is balanced, vs. the parts model that is also an Oasis but that one is unbalanced and obviously older.
    The newer one is about 20 years old but not used much, possibly because that dry bleed port became plugged and the performance went to hell on a deep dive. Distressed the wife considerably.

    Interesting note. I overhauled the old Oasis 2nd, no new parts, put in on my own kit replacing a SP M109 converted to balanced, and it worked just as well for practical purposes. On the bench the 'beater' Oasis 2nd breathes better than the newer and in better shape Oasis. Improvements....right.
     
  6. giffenk

    giffenk Great White

    # of Dives: 500 - 999
    Location: toronto
    4,924
    2,403
    113
    go to frogkick and download all of the sherwood manuals http://www.frogkick.dk/manuals/sherwood/

    find the one(s) that has your gear in it. my impression is that the model numbers tracked the second stages, not the first stages. i have also seen a mix of first / second stages on ebay. not sure if this was factory or shop induced.
     
  7. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
    1,603
    586
    113
    Looks to be the SRB3700. Tthere is no ID mark on 2nd stage like they 'claim', just what is apparently a serial #. This would make the piston 3601-10.
     
    Last edited: Oct 5, 2016
  8. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
    1,603
    586
    113
    couv sent me the 3601-01 piston. Fit right in and after getting it together right magic bubbles appeared. Yes!.
    IP was stable, no other leaks or issues. I took it out on the club pumpkin carve today and it worked fine.

    Moral of the story seems to be you cannot fix a contaminated Sherwood piston except by replacement. It's kind of a good idea but when it gets contaminated by whatever means it's shot.
     
    couv likes this.
  9. miguelation

    miguelation Angel Fish

    7
    3
    3
    Well, after baking the Sherwood piston, model 3601-10, in the glass top cooktop red hot for 45 minutes, ultrasonic cleaning with hot water or vinegar for hours, dishwasher soap combination, degreasers, steel brushing it, boiling it in the microwave oven, also I ground a penny coin to fit inside the scuba tank joke style valve, drilled a small hole 1/16” and clamp the piston to it, so I could blow 3,500# of air thru the air bleed filter hole and that only improved just a little bit. However, yesterday, I put the piston stem inside a long small 1/4” socket, grabbed with locking pliers locked in place, and used a 2,500# pressure cleaner, using the stream fitting, cleaned both sides for over a minute each side, and it worked! . Now is streaming about 60cc/ minute. It was originally contaminated with lubrication from my hands, while placing the orings. The filter was completely clogged after that.
     
    couv and fmerkel like this.
  10. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
    1,603
    586
    113
    Well, damn! Good for you.
    But I'm not so sure those [2,500# pressure cleaner] are readily available to most divers. At least I don't have one.
     

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