G250? Worth servicing?

[buddhasummer]

Thanks Matt, I'll send it to them tomorrow and see what they say. Will then try lowering the ip. Interestingly when I owned a MK25 with 2 G260s I never had this problem. I guess I just want a definitive answer as to what is going on. In total I've tried 5 or 6 different 2nd stages and all have the same problem so it's definitely the 1st stage, that much is clear.

The IP was 130.

 

[halocline]

This is what I don't understand. The end port does provide a linear path for the air coming out of the piston shaft. When this air gets moving, it's going to create a venturi affect in the turret, which could lower pressure in the vicinity of the other ports. This would lower the pressure in other LP hoses. I have no idea how this could force a freeflow in a 2nd stage connected to one of those ports. You would need higher pressure for that.

A simple test might be to put the G250 on the end port, with a LP inflator hose on one of the side ports, everything else plugged. Put an IP gauge on the LP inflator, start a freeflow, and watch the IP gauge. It's going to drop considerably as the venturi effect pulls air from that hose. If it somehow starts rising, there's your answer, but I would be kind of shocked if that's what happened. Maybe someone else with a MK25 can try that. I don't have one......I've worked on several and toyed with the idea of getting one, but I'm cheap and l have plenty 1st stages that work great.

My only guess is that they (SP) are thinking that the end port provides such a strong path for the air that it creates enough of a venturi in the turret to keep the piston pulled up away from the seat and you have what is essentially "free flow" in the 1st stage, only with HP air. But simply interrupting the flow by blocking the mouthpiece should very quickly allow enough pressure to build up in the turret to shut it down.

Don't forget, the MK25 has been around now for way over a decade, and has been a regulator of choice for thousands of technical divers, most of whom use the end port in doubles configurations. In fact, SP has touted the end port as "improving breathing" which is BS but it shows that they've pushed its use for a very long time.

 

[buddhasummer]

I have no tank so unfortunately cannot do the check you suggest. I'm wondering if the issue occurs rarely but because it does occur and because SP don't know why they post an all care no responsibility warning in the MK25 manual. I also wonder if the problem isn't overly reported here because a) perhaps not many single tank divers use the 5th port and b) tech divers are not using two 2nd stages on the same 1st stage (?) ? I have no idea, my set goes to SP tomorrow so will be interesting to hear what they say.

If anyone else reading this thread has experienced the same please post.

It has come up before:

Mk25

 

[buddhasummer]

Update:

Got it back, was told there was nothing wrong with the 1st stage. Advised me to either a) not you the 5th port if using another 2nd stage or b) don't intiate a free flow on horizontal port 2nd stage with Venturi on max.

It's for sale, I'm done with piston regs, I'm going back to diaphragm regs.

I'd like ¥17000 (in yen) including postage by PayPal sent as a "Gift" to avoid fees. Anyone interested "PM" me. I'll send by EMS so to the States should take 4-5 days. Cheers.

 

[halocline]

It's too bad. Something weird is going on. I've always been happy with the older SP regs, although the MK25s that I've worked on are pretty impressive in terms of flow and IP stability. Who knows what's going on with yours.

If you want to really spend some money on old regs, get interested in doublehose. I am a certified cheapskate and have basically never spent more than $100 on a regulator.....except my PRAM. That one kind of blew the bank between the nozzle, all new rubber, re-chrome, and now it looks like I'll have to get Luis's HP 2nd stage.

But, at least the doublehose regs do give you a completely different diving experience.

 

[buddhasummer]

I'll look into DH when I've recovered financially from the single hose vintage obsession I fell into. I don't even want to calculate what I've spent and still don't have a working set, waiting on some DS4s.

 

[buddhasummer]

It's too bad. Something weird is going on. I've always been happy with the older SP regs, although the MK25s that I've worked on are pretty impressive in terms of flow and IP stability. Who knows what's going on with yours.

If you want to really spend some money on old regs, get interested in doublehose. I am a certified cheapskate and have basically never spent more than $100 on a regulator.....except my PRAM. That one kind of blew the bank between the nozzle, all new rubber, re-chrome, and now it looks like I'll have to get Luis's HP 2nd stage.

But, at least the doublehose regs do give you a completely different diving experience.

Different in what way?

 

[scubafanatic]

Almost wish I hadn't too, but having said that I've learnt a lot from all this so even if I go back to Apeks I'm much wiser for the experience. I'm hoping once this issue is sorted that I'll love them as much as do Apeks.

It's put me out of the water until I get this fixed, over confident with my abilities to service, bought 6 G250s, sold all my Apeks equipment prematurely, hindsight is 20/20, now I'm stuck on dry land as have no functioning regs and have spent a small fortune on parts for the G250s. I will love SP, I will love SP even if it's just the G250 with a different brand, Apeks, diaphragm 1st.

You REALLY did sell off ALL your Apeks regs and didn't keep them 'on standby' as 'plan B' ??? WOW!

Over the last couple years I've rounded up/assembled a fair number of MK5/109-156 reg sets, but still kept all my 'modern' reg sets too (mainly an assortment of Atomics/ Apeks / Aqualungs) as they are proven performers for me, and used gear isn't worth all that much anyway in terms of resale 'cash'....they are worth more to me as 'ready reserve' units already paid for.

 

[buddhasummer]

You REALLY did sell off ALL your Apeks regs and didn't keep them 'on standby' as 'plan B' ??? WOW!

Over the last couple years I've rounded up/assembled a fair number of MK5/109-156 reg sets, but still kept all my 'modern' reg sets too (mainly an assortment of Atomics/ Apeks / Aqualungs) as they are proven performers for me, and used gear isn't worth all that much anyway in terms of resale 'cash'....they are worth more to me as 'ready reserve' units already paid for.

Yes, really, and of course lost money on the sale. I have an growing list of decisions made in haste that I got to lament in leisure. Foolish. Although hindsight is 20/20. Over confidence in my ability to service. I figured I could quickly service the G250s, combine them with my new MK25 Evo and be in the water before breakfast, boy was I wrong.

 

[buddhasummer]

Having said that once finished and combined with some DS4s reckon I'll be good to go. Yeah, said similar before...hope springs eternal and all that.