Corrosion and Rust Scubapro MK20 and MK25

[DIY]

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?

 

[LowDrag]

I don't know how to fix that but that sucks. I know of a highly recommended shop in Washington state (if you are nearby) that I could get you the info for if you want it.

 

[tstormdiver]

Lawrence Factor Regulator cleaner does a good job at removing the corrosion, followed by a bath in baking soda water (the bubbling action gets a lot of dirt out of very small crevasses) & a freshwater rinse.. An ultrasonic cleaner also helps a lot. It is rather difficult to get the rust off the springs & the older springs that aren't coated it is common. A small wire brush may help get some rust off.

 

[redacted]

The pitting in the ambient chamber may be a problem if the o-ring does not seal but it might be OK. Rust and verdigris can be cleaned by a tech but the user can prevent it with good cleaning. That pitting in the ambient chamber is on the user, not the tech. The rust or whatever on the spring will not hurt anything.

The flat on the nylon portion of the piston head is normal. It is used in the assembly (and disassembly) of the piston. But, if that damage on the o-ring lines up with that flat, then you probably do have a problem with the ambient chamber; perhaps the pitting is catching the o-ring as the piston closes. Normally, there is nothing pressing that o-ring against the flat because IP would be pushing it the other way. That does not seem to be happening in your case. I'm thinking the top o-ring which should provide the seal is being compromised by the pitting and the lower o-ring that should just function as a dirt scraper is having to make the seal. That would cause that upper o-ring to be pushed against the flat. Not a good situation even if it does seal. You probably should start shopping for a new swivel cap.

 

[scubafanatic]

As far as removing the 'rust' on the spring, would that be pointless, given that the exposed metal would immediately re-rust upon immersion in water, especially salt water ?

 

[nickbutcher]

The spring is coated in Teflon to help stop ice forming. Do not try to clean it, aside from a quick ultrasonic dip.

As has already been pointed out, the flat spot on the piston is normal. How old are the regs? I've seen (and used) a lot worse.

 

[tstormdiver]

The spring is coated in Teflon to help stop ice forming. Do not try to clean it, aside from a quick ultrasonic dip.

As has already been pointed out, the flat spot on the piston is normal. How old are the regs? I've seen (and used) a lot worse.

The springs on the newer MK25's are. The older ones are not.

 

[nickbutcher]

The springs on the newer MK25's are. The older ones are not.

Don't Scubapro allow service technicians to swap them out for newer parts? I've had the old brass pistons replaced with the new composite ones for free during a service.

 

[DIY]

Thanks for the replies. My father had the Mk20 for awhile and then gave it back in pretty poor shape. It did perform flawlessly a couple weeks ago so I'll probably try to fine an ultrasonic cleaner and clean it and the spring from the mk25.

Found a mint condition replacement cap on ebay for $20, yay!

 

[tstormdiver]

Don't Scubapro allow service technicians to swap them out for newer parts? I've had the old brass pistons replaced with the new composite ones for free during a service.

Yes, the springs can be swapped out for newer ones. I was only stating that the older springs are not coated with Teflon.