Corrosion and Rust Scubapro MK20 and MK25

[Hickdive]

When (not if) the Teflon coating on the spring becomes compromised then it simply serves to trap water and promote corrosion.

Fortunately, the corrosion is cosmetic and doesn't affect performance.

 

[axxel57]

OK, I've decide since we I don't have a Scubapro dealer handy and don't trust just anyone to work on my stuff I'd do an inspection on my own gear. I had purchased all the tools sometime back from Peters nows scubatools.com when I was traveling the world and had gotten the basic from our local dive shop at the time.

So I tore into my favorite MK20 which was serviced last August and has been on two trips or 20 dives in the past year. Hear's what I found:

Corrosion inside the Cap

https://www.dropbox.com/s/nxotaazf00t3aq3/IMG_1267.JPG

Pitch marks on the Piston O-Ring. Both my Mk20 and 25 have these notches in the piston.

https://www.dropbox.com/s/jq7z69mqovldjhg/IMG_1269.JPG

I had also purchased a S600/mk25 as a backup reg and found rust on the spring. This reg was serviced serviced 6 months ago so the tech most of thought leaving the rust was OK!

https://www.dropbox.com/s/qjtf46b2omve69a/IMG_1272.JPG

Anyone know the best way to clean these?

DIY

There is some little rust on on the main spring, yes, but really unimportant for the function at this stage.

What I see in the cap is no corrosion, it is the rubber of the piston stem o-ring which has disintegrated and is clinging to this part of the cap wall where the piston is moving while working.

It happens when somebody before has waited too long with a service, but it's not a big deal.

You just have to clean it in ultra sound and polish this area with a Dremel until this wall is smooth again. The stains will stay, but your reg will work perfectly.

Sometimes you will remove parts of the chrome as well, which means 'corrosion' can occur more easily, because the water in the main spring chamber will reach some parts of this area and without the protection of the chrome minerals can stick easier at this area.

A very common problem for me, easy to deal with, and no reason to worry.

 

[DIY]

Thanks axxel57, I lightly cleaned the spring with a brass brush, it appears there's a clear coat of something on it and it's peeling away. The rust formed where the salt water had gotten under the clear coat just as "hickdive" stated. It took about a minute with the brush and it looks like new now. The Mk25 is back together now an the max pressure I can get to the 2nd stage is 145 psi.

I'm not a 100% sure on setting the crack on the s600. Using the In-Line-Adjustment tool I turned the screw until it free flowed and then back in a halve a turn. Should the adjustment knob be fully clockwise or counter clockwise when making the initial set? I don't have a Magnehelic Gauge and I doubt I be getting one.

 

[redacted]

So, the HP piston o-ring has disintegrated due to lack of service yet the regulator had been serviced August 2014 and was performing flawlessly!!! And you think it is a good idea to take a Dremel tool to a regulator sealing surface!!!

Would you provide the name and location of your shop?

---------- Post added August 30th, 2015 at 05:49 PM ----------

I'm not a 100% sure on setting the crack on the s600. Using the In-Line-Adjustment tool I turned the screw until it free flowed and then back in a halve a turn. Should the adjustment knob be fully clockwise or counter clockwise when making the initial set? I don't have a Magnehelic Gauge and I doubt I be getting one.

A half turn is too much. With the adjustment knob fully counter-clockwise, stop any leaking and then another 1/12 of a turn is the book solution. Since I do my own, I leave it just barely leaking and control the leak with the knob as needed.

 

[DIY]

A half turn is too much. With the adjustment knob fully counter-clockwise, stop any leaking and then another 1/12 of a turn is the book solution. Since I do my own, I leave it just barely leaking and control the leak with the knob as needed.

Sounds good. I thought I remember it being pretty simple.

Can the spring be recoated?

I'll be picking up a ultrasonic cleaner this week we'll see how the old cap turns out.

 

[axxel57]

So, the HP piston o-ring has disintegrated due to lack of service yet the regulator had been serviced August 2014 and was performing flawlessly!!! And you think it is a good idea to take a Dremel tool to a regulator sealing surface!!!

Would you provide the name and location of your shop?

---------- Post added August 30th, 2015 at 05:49 PM ----------





awap, if you read carefully you can see that I was referring to something that probably has happened a while ago. I did not understand that this was the first service this regulator had.

These stains in the chrome or brass will stay for the rest of the 'life' of this first stage.

And yes, I think it is a good idea to use a Dremel at the sealing surfaces.

And if you are willing to learn even from me something, then you should, if you ever come across one of those cases, clean this area with Q-Tips and alcohol, and then use a Dremel with those felt discs and polish this part until you feel the heat of the friction in the cap.

If you check with your finger this part you will feel the smoothness of this area.

I polish and lube always these parts where the piston o-rings run.

By this I can make sure that even very old or worn out 1sts work perfectly.

 

[DIY]

Got them both back together today and pool tested. Both still run flawlessly. The cap of the Mk20 cleaned up nicely in 50/50 white vinegar mix follow by a baking soda rinse. It has micro size pitting but doesn't appear to affect it.

Thank You All

Anyone have a better source for parts kits then ebay?