Scubapro MK25 IP Creep

[Tbar]

Hi

I have just services 3 of my MK25s and find that one of then has IP Creep. The IP seams to be set to about 140psi, that is where its return after a breath. But the IP quickly creeps to 150 then on to 155psi.

I have stripped and re-built - no change.

I have swapped parts with another MK25. I find that whichever 1st stage has the one piston has creep. The piston appears to be the problem.

I have had a good look at the piston under a magnifying glass but see no damage.

Any thoughts? Should I replace the piston? Who will sell me a piston?

Thanks

 

[lowviz]

Look for a longitudinal hairline crack. Illuminate the piston from behind to help visualize it.

 

[halocline]

The only place that can leak HP air into the the IP chamber (the cause of IP creep) is the piston/seat mating surface. If the creep travels with the piston, there's something wrong with the edge. You're just not seeing it. Try a 20X jeweler's loupe. If it's a scratch or burr, you can try to resurface it with some fine abrasive like micromesh. Sometimes it works, sometimes not. Chances are you will need a new piston, and it's not cheap. In the U.S. dealers are not supposed to sell parts to us peons, but a few nice ones do anyway. In the EU dealers are required to sell parts to customers. I don't know what the policy is in Australia, but you will eventually be able to find someone that will sell you one.

Occasionally the small o-ring between the two parts of this piston (head and shaft) can fail and cause a leak. But that's a leak of IP into the ambient chamber, not IP creep.

 

[Zung]

You need a jeweler's loupe with 20x magnification to see the scratches. If you don't see anything with a magnifying glass, it could mean the scratches are small and there's a fairly good chance you could get it right with $10's worth of Micro-mesh. A new piston is like $50 if you can find it.

Check out my report here.

 

[Tbar]

Thanks All

I will try to take a high resolution photo, to see if there are any marks.

Here in Australia all the Scuba manufacturers control supply! Why cant they just sell the parts.

 

[Peter69_56]

The only place that can leak HP air into the the IP chamber (the cause of IP creep) is the piston/seat mating surface. If the creep travels with the piston, there's something wrong with the edge. You're just not seeing it. Try a 20X jeweler's loupe. If it's a scratch or burr, you can try to resurface it with some fine abrasive like micromesh. Sometimes it works, sometimes not. Chances are you will need a new piston, and it's not cheap. In the U.S. dealers are not supposed to sell parts to us peons, but a few nice ones do anyway. In the EU dealers are required to sell parts to customers. I don't know what the policy is in Australia, but you will eventually be able to find someone that will sell you one.

Occasionally the small o-ring between the two parts of this piston (head and shaft) can fail and cause a leak. But that's a leak of IP into the ambient chamber, not IP creep.

It takes an act of parliament, 3 depositions and the blessing of 5 high court judges before you can see a parts list in Australia let alone allow a mere mortal buy scuba parts. I think if you are dead you might just have a chance.

After all we are the free country and would never tolerate fixed pricing, price gouging or lack of free trade!

 

[Tbar]

Good news, local dive shop has sold me a piston - all working fine

Bad news over $100AU for the piston, and I am told that was discounted

 

[Peter69_56]

Good news, local dive shop has sold me a piston - all working fine

Bad news over $100AU for the piston, and I am told that was discounted

I have bad news for you. Because you managed to actually obtain a spare for a regulator in OZ, the only conclusion I can come to is you are either dead (see previous post), God came down and blessed you with a miracle, or you managed to swing an act of parliament allowing a once off purchase.

Then again perhaps you are not a mere mortal scuba diver, perhaps you are a (dare I say it) a....................scuba technician..... incognito ?????????? Because there is no way in hell the average Joe Blow can get their hands on spare parts (and please don't strike me deaf, dumb and mute because I mentioned those hallowed words)!

The rest of the world allows some freedom in gaining access to parts but not here. The norm is to make it so tied up in regulations, rules, fixed pricing, price gouging, lack of intent to supply etc etc). The lucky country

 

[Tbar]

Then again perhaps you are not a mere mortal scuba diver, perhaps you are a (dare I say it) a....................scuba technician..... incognito ?????????? Because there is no way in hell the average Joe Blow can get their hands on spare parts (and please don't strike me deaf, dumb and mute because I mentioned those hallowed words)

There is another Aussie trait - the sceptic. I don't think I would have posted the OP if I was the "....................scuba technician..... incognito ??????????", clearly I would have been sure of the solution and had a ready parts supplier. Sometimes when you ask nicely people help, if you don't assume an outcome then other outcomes are possible.

We are a bit of a nanny state, but we are also a luck country :cool2:

Edit - why I posted: I see post by Peter69 and suggesting I was concealing information, misrepresenting or lying, and hence a personal attack. I have not concealed, misrepresented or hidden any information.

 

[Peter69_56]

There is another Aussie trait - the sceptic. I don't think I would have posted the OP if I was the "....................scuba technician..... incognito ??????????", clearly I would have been sure of the solution and had a ready parts supplier. Sometimes when you ask nicely people help, if you don't assume an outcome then other outcomes are possible.

We are a bit of a nanny state, but we are also a luck country :cool2:

Edit - why I posted: I see post by Peter69 and suggesting I was concealing information, misrepresenting or lying, and hence a personal attack. I have not concealed, misrepresented or hidden any information.

TBar, you missed another Aussie trait - taking the piss out of someone. My comment was in jest and a shot at our inability to get our hands on spares for scuba gear in this country. If you read the whole post in context you will see my comments are not a shot at anyone except the control that is so apparent by big business in this country. All to ensure more profit regardless.

So if you felt I was attacking you, I was certainly not and it was never my intent (my apologies). My opinion is that you struck it lucky in finding someone to sell you the parts. It has been my experience that in the main its extremely hard to obtain spares in this country. All my comments were tongue in cheek in that "if you somehow miraculously obtained scuba spares you must be blessed or a tech..... as mere mortals don't appear to have that power"

it was a J.....O.....K.....E