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Thread: SP MK5 1st stage SQUEAL!

  1. #1
    TadPole
    Join Date
    05/14/2011
    Location
    Nashville, TN
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    5

    SP MK5 1st stage SQUEAL!

    Got an OLD SP MK5 back from ST about a month ago. Breathed dry, the piston squeal is next to deafening. Foolishly, I took it diving the other day as a pony reg, but failed to use it at depth and see if this went away. Back on dry land, it still squeals.

    I know this happens from time to time with some pistons, the MK5 in particular, but I wonder what the odds are that it will pass soon. I figure that since it made it out of ST's service area, it must have been behaving itself at the time.

    Maybe it is a function of temperature or humidity or gremlins who don't like vintage gear.

    I can certainly live with it if it is okay at depth (I shoulda checked!) or if it will soon be nothing but a memory.

    I'll probably use it again later this week, but any reassurances from DIY or other types would be welcome. I'm willing to crack it open to lube the piston o-ring, but am hoping that it won't be necessary.

    In the meantime, I want to emphasize ST does fantastic work. I am SO pleased with the two SP "beaters" that came back from them in late March, squeal or no squeal. I love these old regs.

    Thanks.

  2. #2
    Grouper
    Join Date
    04/14/2009
    Location
    S.E. Wisconsin
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    251
    I seem to remember reading in a Sherwood manual that a squeal like this will sometimes originate from the high pressure spring. The cure was to turn the spring around. Easy enough to try.

  3. #3
    Guppy vegas911diver's Avatar
    Join Date
    04/23/2010
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    United States
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    195
    Same thing happens with the Atomic Regs. I had one the other day squealing pretty bad. I disassembled it, turned the spring around in the first stage and generously lubed the piston and everything is fine now.

  4. #4
    TadPole
    Join Date
    05/14/2011
    Location
    Nashville, TN
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    Thanks!

    Thanks guys. Fortunately, I used this reg as my primary today on a near 0 viz quarry dive. After a couple minutes the squeal had completely disappeared. If it comes back, I'll try the spring flip, but for the time being, I'm content to see what happens. Long live MK5's.

  5. #5
    Guppy
    Join Date
    03/13/2010
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    United States
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    My MK15 first stage is squealy until I breathe the tank down to about 2500 PSIG.

    Caused other folks on our most recent dive trip ask whether anyone saw the dolphin that was obviously close out there ;>

    I'm wondering if it's worth the effort to take it back to the shop that did the last annual service and have them turn the spring around after seeing this thread.

    Is there any wear & tear issue associated with the squealing at the high range of tank pressure (high first stage differential pressure)?
    We do not do this thing because it is permitted. We do it because we have to. We do it because we are compelled.

  6. #6
    Grouper
    Join Date
    08/05/2007
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    Oklahoma city, OK USA
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    ok - I'm not a techie guy (well not with regulators anyway - ask me what I do for a living and it's another matter).

    I had a mk2plus which did the same thing after an annual service. It appeared to work, but during dives it made a clarinet like squeak or horn noise that would come and go and varying depths, and pressure of the tank.

    Eventually I called up SP and said "lifetime warranty - fix or replace please" They had a shop work on it - until it stopped. I don't think the shop ever felt like they had a culprit. My daughter dives it now - with no such issue.

    For the record - it always seemed to work, noisy or not. I only cared because it could get annoying during a dive if it went on for a few minutes. I'm sure some folks wouldn't be bothered by it.
    Slowly exhale, relax, your brain will kick in...and if you can breath and think calmly, there's not too much you can't figure out, in any part of life.

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