Yet another free-flow question

[moose_grunt]

I have recently run into a violent free-flow problem on my D2 1st/ classic second rig. It was serviced during a class in January, and has done maybe 20 dives between now and then without problem.

the primary second has started to free flow violently at the surface or shallow depths. It does it randomly, though, and only once per day. It's started when I test breathe the reg, upon entry into the water, and about a foot into descent. It will free flow violently, and there is no way to stop it; the usual tricks (finger in mouthpiece, smacking it, Venturi lever) do not work. I have to turn the tank off. Once I turn it back on, it is fine, and works all day without problem.

IP is at 135, and shows no creep. Adjusting the orifice did not help. My next step is to put new soft parts in the second.

does anyone know why this might happen? Trying to figure out why is killing me. It does not do it consistently; it only happens once per day, maybe 3/5 diving days. Once it has i's fit, I can do three or four dives that day without problem.

if anyone has a theory, I'd love to hear it. This has got me buggered.


thanks,
Jim

 

[cerich]

what cracking pressure is the second set at?

All I can think is that maybe the poppet/spring/balance chamber is getting hung up. You took the service class, have you taken the second apart and looked?

 

[moose_grunt]

Update:

I thought it would be something in the balance chamber getting caught, too. Checked all o-rings and the seat, and everything looked fine. Lubed everything, to no avail. I tried swapping out balance chambers, and still had the problem. This made me think first stage, even though it checked out OK. I switched firsts, and the problem went away, with both balance chambers.

I put a new parts kit in the first, and found the HP seat not only had a deep groove in it (expected), but the area inside the groove was extruded. See pictures below. I didn't save the old seats from servicing my regs at the beginning of the year, so I have nothing to compare to, but I don't remember the seats looking like that.

Servicing the first with a new parts kit seems to solve the problem--I've put about 20 hours over 5 days on it, with nary a free flow.

 

[cerich]

cool, let me know if you have any further issues.