Breathing wet and air leak during vacuum test for Aqualung Mikron ACD

[jdevic]

I recently got my UK-bought Mikron serviced at LDS for the 1st time. Mikron is not commonly sold in Canada, but I was told all AL regs are similar.
After servicing, I noticed it breathed a bit wet when inhaling not looking forward (water seeping in even when Iooking straight down; both primary and octo behave similarly).

When I was away, the DM who happened to have the older version of Mikron checked the diaphragm for me and it was fine. Upon return, the technician checked the 2nd stage again including the mouth piece, diaphragm, adjusting knob and maybe more, and couldn't find anything wrong...

One thing I did notice is that, when doing a vaccuum test inhaling with 1st stage blocked, some air does come in near the exhaust valve area. (My old Mares Abyss Navy II blocked air completely). When I did this at home in the tub facing straight down (no tank), some water did get in as soon as the exhaust valve was submerged.

Is this normal for Mikron/AL? Are water supposed to stop coming in when pressurized?

 

[rsingler]

No. The exhaust valve should seal completely face down, and the seal should get tighter when inhaling.
When inverted, with the exhaust valve high, with the exhaust valve highest, some wet breathing is common as the leaflet flutters during exhalation - air bubbles out and some water seeps in.

I'd remove the cover over the exhaust valve and inspect both the valve leaflet and the case very carefully. There's got to be an irregularity - it's a very simple seal.

 

[jdevic]

No. The exhaust valve should seal completely face down, and the seal should get tighter when inhaling.
When inverted, with the exhaust valve high, with the exhaust valve highest, some wet breathing is common as the leaflet flutters during exhalation - air bubbles out and some water seeps in.

I'd remove the cover over the exhaust valve and inspect both the valve leaflet and the case very carefully. There's got to be an irregularity - it's a very simple seal.

Thank you for confirming that. It is so weird that both my primary and octo are not sealing completely, thus I thought that was normal for Mikron. I will get it checked by the technician again...when I am picking up my Atomic T3 that I ordered out of frustration...

 

[drk5036]

Unfortunately, you're seeing the downsides of the "regular maintenance cycles" that are pushed for regulators. You took a working regulator in and got a...not correctly functioning regulator back. This is not uncommon.

 

[jdevic]

I found a copy of the service manual for the old version of Mikron (I believe the 2nd stage has not changed for my 2018 ACD version). I removed the cover as instructed and was able to isolate the leak to the adjusting knob area. I can notice the change of air flow when i put my finger over the circled area while inhaling. It seems the spins were not lined up as shown in the manual. Could that be why? Both primary and octo are like this... I am not very comfortable nor have the tools to disassemble it further...

 

[rsingler]

Well done! That could easily be the problem.
Now, your challenge is to decide if you can disassemble and reassemble better than the dive shop did, yourself.

It's why the whole DIY Forum exists here on ScubaBoard. Sometimes we don't get the service we pay for.

If you want, send it to me, and I'll fix it for postage.

 

[jdevic]

Thank you sir! I emailed the shop along with the manual and I am bringing it back.

One of the reasons I ordered a Atomic T3 out of frustration (and desire of course ) is because of the 3 year service interval.
Long term I definitely should learn to DIY since this is not my first reg that got messed up after annual service.

 

[rsingler]

Download and use @couv 's thread Regulator Inspection and Checklist (Rev-8)
You'll need to buy an IP gauge for $20.
It doesn't have to be accurate - it's the month to month consistency that matters.

Atomic makes great gear - my favorite piston. But even Monel isn't bulletproof. If you dive steel tanks, tank oxides can sandblast your piston knife edge before your three years are up. Air's making a sharp turn right there.

@couv's checklist will tell you in advance, if you're used to looking at your Intermediate Pressure. When it loses its crispness, and maybe drifts a few psi before lockup, it's time to consider a service.

 

[350xfire]

I found a copy of the service manual for the old version of Mikron (I believe the 2nd stage has not changed for my 2018 ACD version). I removed the cover as instructed and was able to isolate the leak to the adjusting knob area. I can notice the change of air flow when i put my finger over the circled area while inhaling. It seems the spins were not lined up as shown in the manual. Could that be why? Both primary and octo are like this... I am not very comfortable nor have the tools to disassemble it further...


View attachment 701866View attachment 701864

This is quite possible the most frustrating part of Mikron assembly. It appears to all go well but if you look at the valve tube on the inlet side there will be a gap between it and the housing. You really have to tweak the pins to fit into their corresponding grooves. It is pretty satisfying when they finally align and the tube goes in all the way. I have also noticed that you can adjust these Mikrons to perfection and they seem to come out of adjustment more often than other regs. I put mine on the poppet and seat break in machine for 5 minutes to make sure they are broken in before doing final adjustments.

 

[jdevic]

This is quite possible the most frustrating part of Mikron assembly. It appears to all go well but if you look at the valve tube on the inlet side there will be a gap between it and the housing. You really have to tweak the pins to fit into their corresponding grooves. It is pretty satisfying when they finally align and the tube goes in all the way. I have also noticed that you can adjust these Mikrons to perfection and they seem to come out of adjustment more often than other regs. I put mine on the poppet and seat break in machine for 5 minutes to make sure they are broken in before doing final adjustments.

I brought it back to the shop and the technician spent over an hour and overhauled the 2nd stage following the service manual. They did a leak test after servicing and there were no bubbles.
After I got home, I noticed that the primary (left) and octo (right) were slightly different...It seems he did not put the tube all the way for the primary...
I took the primary and octo off the 1st stage, and did the vacuum test again with my finger covering the hose end... the octo was sealed completely when inhaling from the mouth piece. The primary was leaking air from the knob....I guess I have to bring it back again...At least now it is confirmed that it is because of the misaligned pins/grooves..