Scubapro mark V

[racerken]

Hi,

I have a vintage scubapro mark v which is in pretty good condition and I want to clean it out for re-use. My question is regarding the use of metal polish on the internal chambers (which are chrome plated) which have blue surface rust from years of just sitting in my closet. The rubber is fine. My plan is to use the metal polish to remove the surface oxidation then wash thoroughly.

Is this a waste of time in that this is a 30 + year regulator? I think they are great and never had any problems.

Thanks,

Ken

 

[Nemrod]

Nope, there is no such thing as rust on plated brass. The blue you see is a form of corrosion but rust is a ferrous oxidation. To remove the blue residue get some white vinegar and pour it in a container and then soak the plated parts until clean, usually about 30 minutes and then rinse in warm clean water. Where the blue was you will likely now find bare, unplated brass. To fully restore the regulator it will require rechroming.

N

 

[bajashack]

Is this one of those Honkers?

 

[Luis H]

As Nemrod said, the corrosion (verdigris) will come off with a little soaking in white vinegar. DonÃÕ let it sit too long in the vinegar, most of the cleaning happens in the first five minutes and if using undiluted vinegar I would not let it sit much more than Ž½ hour. Some people dilute the vinegar with water by 50%.

After soaking in vinegar I often use some white tooth paste with an old tooth brush to thoroughly clean the threads and totally clean the chrome.

Also as Nemrod mentioned, where the verdigris corrosion was present, you will probably find bare brass spots where the chrome is gone. This is not a big deal since it is mostly cosmetic, but you can have it re-chromed if you want it to look like new. More info on this later.


The Mk-5 is probably one of the most respected and best regulators of all times. It is always worth rebuilding it and diving it. The fact that is 30 years old is immaterial; it will still outlast most modern regulators 30 years from now.

The second stage is the Metal Adjustable 109 and can be upgraded to a Balanced Adjustable (156) during service by just replacing the internal poppet seat, the spring, and associated balancing chamber. It is an easy upgrade that uses all the same parts as the latest Scubapro regulator. And therefore it performs the same as the most advanced modern regulator. With the metal case it has the advantages of durability, also no dry mouth feeling or cold water freezing of the second stage.


If you do a search in the regulator section for the Mk-5, the Scubapro 109, or Scubapro Balanced Adjustable, you will find a lot of threads talking about it. My guess is that this regulator probably has many more followers than any other regulator ever built, including any modern regulator.


Bajashack
No, this is not the honker, the honker is the Mk-7. The mk-7 uses most of the same parts as the Mk-5 but the first stage is much larger to include the sonic low air alarm.

 

[halocline]

If your MK5 has 5 LP ports, it's extremely dangerous and you should probably send it to me for proper disposal.

Actually, there is one thing you need to look at with some caution. The thin bolt that holds the turret (swivel) in place must not be over torqued or it can distort and eventually break. When you take the reg apart, pay close attention to how tight this bolt is, and if it take a lot of force to remove it, you should inspect the threads very carefully. The only thing that could cause a problem would be if someone really cranked down on it during a rebuild. When you put it back together, torque it to 35-40 in/lbs, which is not much more than hand tight.

SP replaced that turret bolt with a stainless steel one that was more tolerant of being over torqued. Who knows, maybe you'll get extra lucky and yours will already have one. If your MK5 is a very old one, with only 2 LP ports, the turret might be held on with a circlip; I've seen a few like that. If that's the case, you could look for a new clip; you might be able to find one at Mcmaster Carr or someplace like that.

 

[racerken]

Wow, you guys are the real thing!

I've got my weekend set aside.

I'm assuming christolube is the recommended lube?

Thanks,

Ken

I'll have pictures of this project later this weekend.

 

[oly5050user]

Wow, you guys are the real thing!

I've got my weekend set aside.

I'm assuming christolube is the recommended lube?

Thanks,

Ken

I'll have pictures of this project later this weekend.

Dug up my old mk 5 out of the basement and rebuilt it last spring..rebuild parts are still available ..can use christolube no problem..using it for my "keep on the boat -beat it up "regulator and my newer ones for trips..

 

[Nemrod]

Use the Christolube,yes, that will be fine, if you can replace all the O rings with Viton rings.

I am a fan of the MkV first stage, mostly the clone versions which were superior in many ways including having a stainless turret bolt, reversible HP seat, large flow through piston, just an excellent first stage for everything but ice diving.

N

 

[racerken]

I think I may have my terminology incorrect.

I have both a 1st and a 2nd stage. I was referring to the turret bolt(I may have misinterpreted what the other poster was referring to...) as the bolt that adjusts the 2nd stage back pressure. I'll take pictures to send in over the weekend to keep me honest. Second thought perhaps the turret bolt is the head of the first stage that allows for multiple low pressure connections?



Where do you get Viton Rings? Mcmaster?

As for this regulator, it's been around the world, Mekong river, South China Sea, Yokosuka, Pearl, smashed by a propeller... Still works. I cannot see myself using anything else!!!

As for my mentality for fixing it myself:
The dive shop wants to charge me 70 plus parts which may run up to 140. In the past when I was diving for a living, it was worth it. You know, back then if I had a failure and under a ship then you use a secondary, grab a buddy, hold my breath or die. Now I only need to dive in a pool to help out with Boy Scouts so I'll do it myself and learn something along the way (thanks to you guys).

Thanks,

Ken

 

[halocline]

You have what was I believe was once sold as the MK5, meaning a MK5 1st stage and a 109 2nd stage. You're really in luck. That's a great 2nd stage. SP has just introduced a new version of a metal 2nd, and I bet it's going to be very expensive.

The turret bolt is a part of the first stage, it's what holds the swivel with all the LP ports in place.