Question MK11 Scubapro reg question

[Tressamb]

Just purchased this with C370. Prob 20 dives in. When I inhale it seems like the unit drags and makes an almost farting like sound. Had shop adjust it and it stopped but does it below 45ft only. What can be causing this?
I’ve tried all the reg adjustments on the mouthpiece and it doesn’t seem to change anything.

 

[lexvil]

Can you tell if it’s the 11 or the 370? My bet at first would be the diaphragm testing it on the surface dry but at 45 ft. Sounds like something else, is the adjuster (knob on your left side) fully open? Is the “dive” “predive” lever fully on “dive”? If so take it back.

 

[Nemrod]

The IP could be (very) low. Having the scuba shop adjust it does not inspire confidence with me. Did they say exactly what they adjusted? I like details, right now we have very little.

 

[Tressamb]

Can you tell if it’s the 11 or the 370? My bet at first would be the diaphragm testing it on the surface dry but at 45 ft. Sounds like something else, is the adjuster (knob on your left side) fully open? Is the “dive” “predive” lever fully on “dive”? If so take it back.

Its the MK11 first stage with the C370 second stage. so, both. the adjuster knob is set to dive.

 

[Tressamb]

The IP could be (very) low. Having the scuba shop adjust it does not inspire confidence with me. Did they say exactly what they adjusted? I like details, right now we have very little.

They said they adjusted it by taking it from

The IP could be (very) low. Having the scuba shop adjust it does not inspire confidence with me. Did they say exactly what they adjusted? I like details, right now we have very little.

sorry..not sure what happened there. They have a sticker on it that says IP 143. 2nd Cp 1.2H2o adjusted Octo CP 2.2 H2O. I don't know what they did either. What should the IP be?

 

[BoundForElsewhere]

IP is at 143? no, no, no, no. IP should park at around 132ish. 143 is putting not a huge amount but more than necessary pressure on the 2nd stage valves. MK11's are easy to adjust... depressurize the regulator, use an allen key to back pressure off the diaphragm, and take an IP reading again. You can get yourself an inline pressure gauge from DRS and do it all yourself. Just don't try to turn the allen key with the tank open. you will score the seat.

 

[lexvil]

Its the MK11 first stage with the C370 second stage. so, both. the adjuster knob is set to dive.

Can you tell from which the noise is coming? The adjuster is the knob thing athat sticks out of the side, the dive/predive lever is between that and the main body of the reg.

 

[lexvil]

IP is at 143? no, no, no, no. IP should park at around 132ish. 143 is putting not a huge amount but more than necessary pressure on the 2nd stage valves. MK11's are easy to adjust... depressurize the regulator, use an allen key to back pressure off the diaphragm, and take an IP reading again. You can get yourself an inline pressure gauge from DRS and do it all yourself. Just don't try to turn the allen key with the tank open. you will score the seat.

I run most of mine at 145

 

[Tressamb]

Can you tell from which the noise is coming? The adjuster is the knob thing athat sticks out of the side, the dive/predive lever is between that and the main body of the reg.

I’m 45ft under water. I cant tell. It seems line it’s coming from the mouthpiece, and I’ve played with all the mouthpiece adjustments while under water. No real difference.

 

[Nemrod]

Per the SM the Mark 11 IP should be between 9 and 10 bars (125 to 145 psi).

The cracking effort adjustment should be around 1.2 inches. There is no reason to set the secondary to such a high cracking effort, use the adjustment knob instead and turn it in a turn or two on the secondary/octo to prevent free flow. The secondary/octo should be at the same setting as the primary for an adjustable regulator.

At this point, I would remove the second stage poppet and balance chamber and ensure that the assembly is properly lubricated, a wild guess here. I know that people freak out, but I find silicone (100% food grade) a better choice here than the "other" stuff. But being as it is a new regulator, the shop is going to use the O2 safe grease which I found is inadequate and cakes up and gets hard or washes off.

Does this phenomena occur with both second stages or just the primary?