Help with Mares MR12 IV / Navy 2nd stage

[mkaz]

While working on a Mares MR12 IV / Navy 2nd stage, I had to remove the by-pass tube to service the o-rin under it. The other of the by-pass tube that attaches to the mouthpiece channel did not have an o-ring.
There only was some black, deteriorated stuff around the tube.
The tube diameter is 8.8mm, the hole 9.0, leaving very little space and no o-ring groove. When test assembled there is no space at all between the tube protusion and the body. Everything is a tight fit but not airtight.
Should this be assembled with glue or some kind of sealing compound? If yes, what kind?
Anybody with experience with this particular reg?
On later models, such as the XTR, the diagram shows a slightly different design and an o-ring. I tried fitting a very small o-ring but there is not enough space.
Any help would be appreciated.

 

[John C. Ratliff]

I have one of these second stages, but have never taken it apart. I also am hesitant to do so, as so far there is no problem with it. Since it is a tight fit, and it is mainly at ambient pressure, I would simply use the adhesive sealant, Clear RTV Silicone. That way you could take it apart again if needed.

The diaphragm on mine is also without an O-ring, and it seals just fine. Test that by putting the diaphragm in, the top cap on it, and screw in the retaining ring. Then put your finger over the LP screw-in for the hose to block it off, and inhale. You should get an air tight seal.

Good luck,

John

 

[eelpout]

I sold and serviced them for the years , that part was not intended to be taken apart, your schematics show that.