Scubapro MK17 Evo Retaining Ring & Cap

[DiveDay]

I have a dumb newbie question about the Scubapro MK17 Evo.

I dropped my entire rig on the 1st stage (won't be doing that again, hint: don't leave it standing on a bench). Thankfully it was set up for yoke at the time and the first stage came off the cylinder and nothing was damaged too badly. It was checked out by my shop and it was fine (IP, etc) but the plastic "bumper" cap was damaged. I got a replacement, pushed the old cap off with my thumbs and put the new one on. The moment the new cap went on it basically fused to the metal retaining ring underneath. I'm not sure if the cap is supposed to spin freely, attempting to rotate it actually unscrewed the entire retaining ring.

I couldn't find a MK17 Evo manual but the MK17 is pretty close: https://www.divestock.com/downloads/dl/file/id/240/scubapro_mk17_af_rev_a_10_117_x00.pdf

I'm talking about parts equivalent to 43 and 17.

Should I be concerned? Is the bumper supposed to rotate freely? It doesn't seem to affect function in any way.

Lastly, when the retaining ring unscrewed a bit of liquid came out. It seemed like a mixture of water and white silicone-like lubricant along the threads. Is that normal? I wiped it off and everything else seems dry. It was only a few drops but it made me wonder if water is getting into somewhere it shouldn't.

Thanks for your help!

Edit: After a bit more reading I found Plastic Cap problem ScubaPro MK25 which seems to indicate the plastic cap design is not great. With a bit of elbow grease mine does rotate, but only in one direction without unscrewing the retaining ring. I think I will leave it as-is, removing it would likely break the plastic tabs.

 

[Newdiv]

Part 17 holds the diaphragm for your environmental seal. You have unsealed it if you unscrewed it. While under pressure(3000psi) tank put it back on to seal it again. Make sure you see the diaphragm “suck” down once you turn off air and purge to ensure it’s sealed. (You also might want to spray soapy water before sealing to ensure no bubbles,while under pressure, thoroughly dry before putting part 43 on)

 

[DiveDay]

Make sure you see the diaphragm “suck” down once you turn off air and purge to ensure it’s sealed.

Thanks for the reply! I'm not sure how I can remove 43 from 17 without breaking the retaining tabs at this point. With them assembled together it's difficult to see the diaphragm underneath. Any tips? The fit is so tight trying to rotate 43 unscrewed 17. There's no room to try to pry them without either marring the retaining ring or putting some gouges into the cap.

 

[Newdiv]

Place a thin flathead screwdriver into the side or through the top angled to the sides of part 17 and slowly pry it up. It’s not that fragile. More important to have your reg sealed than a decorative cover.

 

[DiveDay]

More important to have your reg sealed than a decorative cover.

I can't argue with that. I managed to pry it off using an electronics screwdriver. Unlike the retaining ring on the Mk17 the Evo doesn't require a special wrench (phew!) so I unscrewed it using a large crescent wrench.

I put it on a full tank (~2900psi), screwed it back on with the wrench, then cycled the pressure a few times. The diaphragm "sucked in" as you indicated it should.

Thanks a lot for your help! I'm not really regulator savvy - for my education, why does this have to be done under pressure?

Also, I assume that stupid bumper cap has to be removed every time you adjust the IP, right? I don't understand why Scubapro didn't put some threads on it. Between it and the proprietary spline nuts on their hoses I'm not feeling much love for the brand right now. They seem to do their best to prevent any kind of DIY. Ugh.