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MK25 Whistle

Discussion in 'Regulators' started by Teller, Jun 1, 2013.

  1. Teller

    Teller Tech Instructor

    # of Dives: I'm a Fish!
    Location: Harker Heights, Texas, United States
    My MK25 has a whistle sound when I inhale. I have already put extra lube on the piston and it did help but its still making the noise. I cycled it over 30 times but its not resolved. Ideas?
  2. halocline

    halocline Solo Diver

    So, what you mean by "put extra lube on the piston" you took the reg apart, removed the piston, then lubed and re-installed? If not, you probably didn't get the lube exactly where it needed to go. Sometimes a bit of lube on the spring ends will help, sometimes turning the spring around helps, sometimes just taking it apart and re-installing the o-ring and bushings helps.

    Usually you can't make it stop humming unless you take everything in the HP o-ring set up out and do it over. Who knows why....you could also just ignore it, it's probably not indicative of a problem.
  3. triggerman365

    triggerman365 PADI Pro

    # of Dives: 500 - 999
    Location: Florida
    When you say you put extra lube on the piston, where did you apply the lubricant? Also, is this a brand new reg? or recently serviced? If it is new I'd take it to your LDS. If this is just developed you may need to have the reg serviced.
  4. Zung

    Zung Loggerhead Turtle

    # of Dives: 500 - 999
    Location: Geneva, Switzerland
    Yeah, inspect the HP O-ring, the one that's between the bushings on the seat retainer side. It MUST have a red stripe on it if it comes from an original service kit: this is to tell it apart from the other O-rings of the same size but are softer. I'd replace it, peace of mind for a dime; it has to be a 2-010, Duro 90, Viton, EPDM or PU.

    I also put a lot of lube on it, no matter what SP says.
    triggerman365 likes this.
  5. Teller

    Teller Tech Instructor

    # of Dives: I'm a Fish!
    Location: Harker Heights, Texas, United States
    Ya i pulled it apart and lubed the piston. Ill try the spring ends. I tried flipping the spring. It didnt help.
  6. Kunundrum

    Kunundrum Divemaster

    # of Dives: I just don't log dives
    Location: Ajax Ont. Canada
    what he said, every time I encountered this was because the wrong o-ring was installed.
  7. redacted

    redacted Guest

    A duro 90 o-ring and lots of Christolube fixed the problem.
  8. Pedro Burrito

    Pedro Burrito Moderator Staff Member ScubaBoard Supporter

    # of Dives: 5,000 - ∞
    Location: Boussens, Canton de Vaud, Suisse
    I took my MK25 in for the first annual service about a year and a half ago. It was fine before the service. It whistled when I got it back in the water. I took it back for service twice more. The whistling was so bad that someone followed me into the bell at Blue Grotto and said, "Dude, you got to get your reg serviced!"

    The tech finally told me the piston was scratched and he replaced it along with a completely new service kit. Thankfully, Scubapro stopped the annual requirement. I'm not looking forward to having it serviced again in December.
  9. halocline

    halocline Solo Diver

    Does that mean that you have found several cases where the tech/dealer installed the wrong o-ring? That's pretty scary considering it's clearly marked which one is the correct one, and anyone can easily tell the difference between a duro 70 and a duro 85. (that's probably what's in the kit, not a 90)

    Chalk up another one for the brilliant scheme of limiting parts and service to 'certified' techs.
  10. redacted

    redacted Guest

    I'm not sure how a scratched piston causes a whistle. If the scratch is in the wrong place, I would expect a leak?

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