halocline
Contributor
Looks like it was pinched upon installation, or maybe there's a burr on one of the plastic bushings.
The song of a MK25
- Thread starter Zung
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
elan
Contributor
Zung you can probably sell that o-ring on ebay. I was smiling yesterday when I saw a guy selling used D poppets at a high price. (those that do not have a nut)
divingtactics
Contributor
Easy for me to say now that you have disclosed the issue, but my money would have been on that little piston stem o-ring too, given that you had small bubbles coming from the ambient chamber.
diverdoug1
Contributor
Ah! The mating song of the Mk25! I know it well. My Mk25 went into heat after its last service. The squeal of delight was most noticeable when the Mk25 had it's lips pused around a full tank, but died off as the tank did. After a brief argument with my LDS, when he tried to tell me that this was "normal" even though I had never heard it on any of my previous 500+ dives with it, he begrudgingly re-serviced and SHAZAM!!! The Mk25 was no longer in heat. He could not tell me what he had done to fix it (but I suspect he just spayed or neuterd it). On my last dive trip I once again heard the forlorn mating squeal of a Mk25, but it was coming from another diver. At the end of the dive, I approached the diver and noticed that her reg was in fact of the Mk25 tribe! Her story of the reproductive vocaliizations of her Mk25 matched mine. I think, perhaps, an expensive goverment study is in order here, with lots of yummy tax expenditures! Or possibly, in this season of brotherly love, SCUBAPRO could give the customers a break and get thier sh-t together. Happy holidays
R
redacted
Guest
While I'm sure there are those who would object to the technique, I have had some success temporarily stopping the Balanced Piston mating call by adding a little lube through the inlet - remove the filter first. Although, in Zung's case, the problem was more than just in heat, it was %^&$ed.
elan
Contributor
I had my MK25 whisteling and today I have finally decided to fix it. It was a reg bought new last winter an was whisteling since the very beginning. I disassembled the reg and the piston was fairly well lubricated. I cleaned all lube and lubricated with new. Put everything together and while whisteling had got it started lealing air into the ambient chamber. Replaced the hp oring with a PU and reassembled again. No whisteling no leaks. Its strange that the new rings have these kind of problems.
Buy the tech a piston bullet from Herman.
R
redacted
Guest
No bullet tool necessary with the Mk20/25. The piston "knife" edge is dull (tech safe).
The type of damage pictured is nibbling probably caused by extreme extrusion. Wrong hardness fr maybe incorrect installation of the bushings. There are many ways to incorrectly install those bushings and I am unsure about how sensitive the design is to the correct installation.
The type of damage pictured is nibbling probably caused by extreme extrusion. Wrong hardness fr maybe incorrect installation of the bushings. There are many ways to incorrectly install those bushings and I am unsure about how sensitive the design is to the correct installation.
OP
Zung
Contributor
Well, I dunno.
According to the very early service manual, P/N 41-900-002, you use the assembly tool to hold the bushing and the o-ring while you plug the piston from the other side. I could clearly feel the moment when the o-ring gave in.
Then, with the coming of the composite piston, they issued the EB #267 describing a modified procedure where you install the 1st part of the bushing, install the piston in the cap, screw it down, then install the o-ring and the other bushing, one by one, from the other side.
I have the feeling the new procedure is less stressful for the o-ring. Here's a pic from a different angle, there's a round cut that could be caused by the piston stem: its edge is not that blunt.
According to the very early service manual, P/N 41-900-002, you use the assembly tool to hold the bushing and the o-ring while you plug the piston from the other side. I could clearly feel the moment when the o-ring gave in.
Then, with the coming of the composite piston, they issued the EB #267 describing a modified procedure where you install the 1st part of the bushing, install the piston in the cap, screw it down, then install the o-ring and the other bushing, one by one, from the other side.
I have the feeling the new procedure is less stressful for the o-ring. Here's a pic from a different angle, there's a round cut that could be caused by the piston stem: its edge is not that blunt.
R
redacted
Guest
Not so much blunt as dull. Big difference between the Mk25 and the Mk10 knife edges. I suspect that the procedure change was because when you installed the two bushings and the o-ring and then turned the tool in to hold it all in place, it was possible for the o-ring to slip out from between the bushings and block the insertion of the piston.
I don't think you could produce that complete circumference damage you experienced with piston installation, even with a Mk10. The small piece that broke loose is probably what finally produced the leak.
I don't think you could produce that complete circumference damage you experienced with piston installation, even with a Mk10. The small piece that broke loose is probably what finally produced the leak.
Similar threads
