Scubapro mk10 piston wall damage.

[p_kos]

I have polished a similarly “pitted” MK20 with the @rsingler recommended micromesh (few minutes spinning it around in there with a finger) and it came out perfectly smooth and works without leaks. I have also assembled a couple regs with the same level of wear without polishing and they too work just fine. Without polishing, even if it works fine, I suppose the oring may be prone to failing sooner running over a rougher surface but I have no long-term data/experience to confirm this.

 

[rhwestfall]

I've got a mk-20 with a bit of crud on the wall. It seems to have some drift. Wondering if it is the cause. Need time to work on it...

 

[p_kos]

I've got a mk-20 with a bit of crud on the wall. It seems to have some drift. Wondering if it is the cause. Need time to work on it...

I would put the piston edge under magnification and rule that out first, although I assume you’ve done that already.

 

[Still Kicking]

I've got a mk-20 with a bit of crud on the wall. It seems to have some drift. Wondering if it is the cause. Need time to work on it..

Pretty sure drift/creep is related to the HP seat and the piston edge. The wall damage would let air pass by the main piston o-ring and bubble out of the body. Easily evident.

Drift isnt uncommon with SP pistons - not a huge deal if they lock up reliably.

 

[rhwestfall]

Drift and creep are NOT the same thing....

 

[Still Kicking]

Drift and creep are NOT the same thing....

I know.

 

[Tr4lover]

Got the 108hp all ready for Mexico this weekend.

 

[Tr4lover]

I just thought of a possible solution. I have a master cylinder boring tool that I use to restore a old Triumph tr4 master/slave cylinders. I'm thinking bores are about the same size as a mk10. This tool would allow me to cross hatch and clean up most of my mk10.

This being said I'm no expert on diving equipment. Cars are more in my wheel house. Would you see any benefits in using this tool?

 

[lexvil]

I just thought of a possible solution. I have a master cylinder boring tool that I use to restore a old Triumph tr4 master/slave cylinders. I'm thinking bores are about the same size as a mk10. This tool would allow me to cross hatch and clean up most of my mk10.

This being said I'm no expert on diving equipment. Cars are more in my wheel house. Would you see any benefits in using this tool?

It may make you feel better about tossing it the scrap heap…

 

[p_kos]

I just thought of a possible solution. I have a master cylinder boring tool that I use to restore a old Triumph tr4 master/slave cylinders. I'm thinking bores are about the same size as a mk10. This tool would allow me to cross hatch and clean up most of my mk10.

This being said I'm no expert on diving equipment. Cars are more in my wheel house. Would you see any benefits in using this tool?

Sounds too aggressive, this is soft brass after all. You risk taking too much material off and then the piston head wont seal. Run it as is or use micromesh (very very fine sandpaper) with finger pressure.