Scubapro MK10 Rebuild Question - 1st Time DIY

[uncfnp]

Hi guys. Another question. This is a pic from an MK 10 of the spring and piston from an ebay purchase. Just did a lite cleaning so far but concerned about all the corrosion on the piston. This is my first time servicing a first stage but looks pretty bad to me. So two questions...

Would this piston still be servicable after a proper cleaning?

What would cause this type of damage? It is an Mk 10 with the environmental seal. The chamber was packed.





Thanks!

 

[halocline]

Someone didn't do a great job of packing the chamber. It's a little trickier on the MK10 than the MK5 due to the way the body assembles. Anyhow, moisture (probably salt water) penetrated the grease and got trapped against the piston head. It's not uncommon. If the sealing edge, shaft in the vicinity of the HP o-ring, and the o-ring channel for the large LP o-ring are clean (they appear to be in your photos) then I'd use a little very fine emery cloth or sandpaper to try to remove as much surface rust as you can, and make sure there's a coating of grease on the spring and piston head. Then I might start looking for a replacement piston, but I wouldn't fret over it too much. If you find one at a decent price, get it and replace it at the next service.

If you're going to re-pack the chamber, I would consider using silicone grease, I think it's better for that. A pair of my MK10s are packed with tribolube, and so far it's worked well, but I also have taken great care to make sure the chamber is completely filled with no voids whatsoever.

 

[redacted]

I would not call that damage. Rust in that location is just a little cosmetic defect. Clean it up a bit but don't worry about getting it all removed. Good post dive care will keep it in check.

 

[Couv]

I would not worry too much about the rust. Just clean it away as Halo suggested-Scotch Bright might be a little easier to use than sand paper.

The important thing is to have a really good look at the knife edge of the piston. Run your thumb nail around the edge and feel for nicks or other imperfections. If you have a 10x magnifying glass that would help.

If you find any issues, (or not) have a look at this thread http://www.scubaboard.com/forums/re...6-scubapro-piston-there-life-after-death.html where Halo and Zung give detailed instructions on how to dress the edge.

If you're not feeling up to that, I'm pretty sure I have a NOS MK 10 piston for sale-but you won't get your DIY merit badge.

 

[scubafanatic]

Hi guys. Another question. This is a pic from an MK 10 of the spring and piston from an ebay purchase. Just did a lite cleaning so far but concerned about all the corrosion on the piston. This is my first time servicing a first stage but looks pretty bad to me. So two questions...

Would this piston still be servicable after a proper cleaning?

What would cause this type of damage? It is an Mk 10 with the environmental seal. The chamber was packed.

View attachment 218391

View attachment 218392

Thanks!

Your photos have just reinforced my 'policy' of not packing any of my MK 5's with anything, but instead just leaving them 'open' and flushing/rinsing the ambient chambers instead.

 

[ams511]

Your photos have just reinforced my 'policy' of not packing any of my MK 5's with anything, but instead just leaving them 'open' and flushing/rinsing the ambient chambers instead.

Not only that it is PITA to remove the lube.

 

[uncfnp]

Not only that it is PITA to remove the lube.

Amen! That stuff was thick and sticky. Is it worth the effort to replace or can I leave the lube out. If I do omit the lube, do I leave the seal off?

 

[uncfnp]

...

If you find any issues, (or not) have a look at this thread http://www.scubaboard.com/forums/re...6-scubapro-piston-there-life-after-death.html where Halo and Zung give detailed instructions on how to dress the edge.

If you're not feeling up to that, I'm pretty sure I have a NOS MK 10 piston for sale-but you won't get your DIY merit badge.

Thanks couv but the edge looks and feels pretty darn good to me.

The cleaned piston...

 

[halocline]

Amen! That stuff was thick and sticky. Is it worth the effort to replace or can I leave the lube out. If I do omit the lube, do I leave the seal off?

Unless you're using the reg for really cold water, there's no reason to re-pack it. Take the boot ("seal") off and save it. Someone will certainly buy it from you, those SPEC boots are hard to find.

It looks like you did a really good job of cleaning up that piston!

 

[uncfnp]

Thanks halocline.

Those cone filters are darn expensive. Can you clean and reuse?