Reg Troubleshooting

[aquaregia]

I was using my regs in the pool (SP Mk10 w/ R109s adjustables) and I noticed that if I breathe very hard/quickly off one of the 109s it seems to close up an refuse to give air as fast as if I breathe slowly. This isn't the case on the other 109. The 109 that I'm having problems with has a brand new poppet, seat, o-rings and a new plastic orifice. The other 109 has a new (ok, flipped) seat and o-rings, but still has the original metal orifice. What is this problem likely to be caused by? My initial inclination is that something on the diaphragm is unhappy.

Additionally, the Mk10 whines pretty loudly when I breathe hard or inflate. Is this a sign of problems?

 

[Bubbletrubble]

Have you examined the condition of the diaphragm in the problem second stage?

One possibility is that the diaphragm needs to be replaced. When you inhale, this creates a negative pressure inside the second stage body, which under normal circumstances pulls the diaphragm in. This depresses the lever which begins air flow. It might be possible that the old, floppy diaphragm is getting sucked in so far that it's plugging up or severely hindering the flow of air. The way to test this would be to swap the diaphragms in your two 109s. If the problem follows the diaphragm, that's your problem. Be forewarned that I have no specific experience working on the 109s.

I have no experience with the MK10 first stage either. Is the IP within normal limits and stable? How is the IP recovery?

Let us know how your troubleshooting works out...

[Edited later: I see that awap has just posted. With all things involving regs, I'd listen to what he has to say.

 

[redacted]

I believe there have been a few versions of levers in the 109s and I have heard there can be some conflict between the new style poppets and the older style levers. I had one lever on a 109 that sat way too high ( with the cover off) and required that the orifice be screwed in further than I wanted when the cover was installed. So the lever should be a prime candidate. I would not expect the orifice to be the problem.

Your description make me think the lever is the problem. You should be able to see the operation of the lever on the poppet on each of your 109s which would help you locate the problem. New levers are fairly cheap.

I always like to tune my rebuilt metals with the cover off which is how I found my problem lever. Adding the cover usually requires a minimal addition adjustment to stop a slight freeflow.

 

[aquaregia]

The lever would make sense. I had quite the time getting that one reassembled, and I wasn't able to get it below 1.5" without it freeflowing.
Cheers

 

[Couv]

Yes, my bet is on the lever too. I had a similar problem with a new style "Duro" poppet. I just could not get it to adjust properly until I replaced the lever with a new one.

Having said that, Bubbletrubble points out an important technique in trouble shooting. "Convict the bad part" an old aircraft maintenance instructor I knew would say. Swapping parts one-at-a-time, not just until you have solved a problem, but in order to duplicate it. This can be an important step in understanding a discrepancy in a system where the problem is not obvious.

While I'm thinking of it, I should mention when you have the diaphragm out, have a look at the surface where the lever makes contact. Some of the plastic buttons get engraved and could cause the lever to drag. Not hard to fix, just rotate the diaphragm 90 degrees or polish it out.

I look forward to your findings,

Couv

 

[halocline]

It's probably the lever, Awap is rarely wrong....except in regards to his opinion of double hose regs.

The Mk10 whining is a resonance issue with the piston; you fix it by re-lubing the HP piston o-ring and maybe flipping the spring; the spring bit might help, but a well-lubed HP o-ring will cure it. Usually this just means rebuilding the reg, as you have to take the thing apart anyway to get at the o-ring, and unless it's brand new you might as well replace it, and the seat while you're at it. Unless the noise really bothers you, you can just dive with it until you're ready for a rebuild. If you recently paid someone to rebuild it and it does it, I'd bring it back and have it done over. The unfortunate part is that once you remove the piston, you really should replace the seat because you'll never get it lined up exactly the same, so you'll have 2 grooves cut in the seat by the piston edge, and especially with a MK10, it'll creep. You might get lucky, but probably not.

 

[aquaregia]

I just redid the Mk10 with the help of my LDS tech. We used a fairly insane amount of lube on the o-ring. If it's just a ... cosmetic ... issue I don't really mind.

 

[Zung]

... You should be able to see the operation of the lever on the poppet on each of your 109s which would help you locate the problem...

"Each" is the magic word: more explicitely, since you're lucky enough to have a good one, put them side-by-side and compare: lever height, effort required to move the lever, smoothness of the mouvement, condition of the diaphragm, and so forth.

 

[halocline]

I just redid the Mk10 with the help of my LDS tech. We used a fairly insane amount of lube on the o-ring. If it's just a ... cosmetic ... issue I don't really mind.

Depending on the IP, number of washers you used, and the seat you used, you could try switching to the next tallest seat in the kit, which will lower the IP, then adding a washer on each end of the spring. (You're not supposed to use more than three washers total). The idea is that the plastic washers dampen the spring. I'm not sure how well that works, because I've always been able to get rid of the honking just by rebuilding.

Or you could live with it, it won't hurt anything and it might just go away on it's own.

What's a little weird is that the tech working at the dive shop did not catch the lever issue.

 

[knowone]

Contrary to popularly held beliefs. Scubapro Regulators are destructable.