User avatar
Fibonacci
Vintage Diver
Posts: 98
Joined: Wed Oct 19, 2016 5:08 pm
First Name: Graeme
Location: Melbourne, Australia

Scubapro MK V yoke retainer?

Sun Sep 03, 2017 1:01 am

Just pulled down a late model MK V with G250... while the first stage is generally in good condition, indications are it was not rinsed off properly then stored for a long time with the dust cover on before I got hold of it. The area under the dust cover has retained salty moisture and allowed corrosion to take place.

The area of the yoke retainer bolt (item 29 #10-101-147) that seals against the tank valve o-ring had some corrosion and bubbling under the chrome.
After pickling in 50:50 white vinegar, then ultrasonic cleaning the chrome lifted right off leaving bare brass with some pitting.

It would seem to me this part may need replacing or at least the pits sanded out with wet and dry paper on a sheet of glass... what is the VDH opinion please?

Not sure if this is still available as a spare part or the pitting it not worth worrying about but being bare brass now it will probably corrode ?
You do not have the required permissions to view the files attached to this post.
'A man can never have too much red wine, too many books or too much ammunition' Rudyard Kipling

User avatar
Herman
VDH Moderator
Posts: 1234
Joined: Thu Oct 25, 2007 1:45 pm
Location: Raleigh NC

Re: Scubapro MK V yoke retainer?

Sun Sep 03, 2017 7:22 am

I would just lap it on a piece of glass with using 300-400 grit sandpaper to remove the any pits followed with 800-1000 grit sandpaper to polish it. I prefer wet/dry sandpaper with a good amount of water on it. While it detracts from the appearance of the reg, it does not hurt anything functionally. Use a wide figure 8 pattern to lap, rotating the part every few passes to prevent uneven material removal.
Herman

User avatar
luis
VDH Moderator
Posts: 1598
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: Scubapro MK V yoke retainer?

Sun Sep 03, 2017 10:30 am

That part has not been available for many years, unless you find a NOS somewhere, but it is not likely that you will find one. You may get a used one in better condition, but it is probably not worth the trouble.

I would follow what Herman recommended. It doesn't have to be perfect for that face seal O-ring to create a good seal, but the smother the better.

The O-ring actually keeps that surface dry, so corrosion will not be as bad as it may seem. Not having chrome in that surface is not that bad. The outer edge may not look great, but it will be mostly cosmetic.

Good luck.
Luis

Buceador con escafandra autónoma clásica.

User avatar
couv
Master Diver
Posts: 347
Joined: Tue Jul 18, 2006 10:26 pm

Re: Scubapro MK V yoke retainer?

Sun Sep 03, 2017 10:38 am

As always great information from Herman on dressing the sealing surface.

The yoke retainer is one of the undesirable points when it comes to the MK5. Unlike most other SP models, it cannot use the universal yoke retainer or DIN, so when you have an issue such as the OP's you're almost stuck with it.

I'm not a big fan of using vinegar in any concentration on regs already showing signs of compromised plating. Chrome really does not like vinegar, and vinegar does not like chrome. I know it's used and extolled by many, but something more gentle like 5-10% phosphoric acid does just as good a job (or better) and the smell is more pleasant. I'm sure there are other products equally as effective. I think Bryan uses Salt-X.

Anyway, a little elbow grease and you're MK 5 is back in business.

(Edit: Good morning Luis, I did not see you at the typewriter...er computer)
A sincere THANK YOU to all at VDH who make this wonderful resource available and to all the thoughtful contributors.

User avatar
georgeaustin
Master Diver
Posts: 272
Joined: Mon Nov 04, 2013 8:41 am
First Name: george
Location: Los Angeles CA

Re: Scubapro MK V yoke retainer?

Mon Sep 04, 2017 7:33 am

I have lapped these back to service using the technique that is outlined above. They have performed quite well since.
One of mine even had a defect possibly up to a couple mils deep where I had dropped it onto that face.
Obviously I needed to lap past the chrome plating thickness but I've still got high quality, corrosion resistant marine brass there. Patience and a nice flat surface to lap on. I used a surface grinder bed with wet dry paper taped to it

User avatar
Fibonacci
Vintage Diver
Posts: 98
Joined: Wed Oct 19, 2016 5:08 pm
First Name: Graeme
Location: Melbourne, Australia

Re: Scubapro MK V yoke retainer?

Wed Sep 06, 2017 11:07 pm

Thanks for your advice guys, turns out the pitting wasn't so deep and lapped out quickly using 320/800/1200 grit wet and dry on some plate glass lubricated with Ed's Red (overkill but I had some handy... a very useful witches brew I usually use to free 'frozen' metal parts).
Now for a VDH kit :mrgreen:
You do not have the required permissions to view the files attached to this post.

Return to “Single Hose Regulators.”

Who is online

Users browsing this forum: No registered users and 4 guests