Massive SP D350 freeflow in dive mode

[ericpitar]

Here's a close-up of the set screw. A bit blurred. Could this last another year? It doesnt seem to be that bad now that I've looked at the close up but I could be mistaken.

 

[Isaac-1]

Yes, that's some corrosion you see. It was actually recently cleaned for the initial service but has worsened in the short amount of time since then (span of less than a month). I'm waiting for parts to arrive and will have that changed as soon as I get em.

Until then, I'm very tempted to remove the rubber cover to check/correct the diaphragm positioning for myself. A few questions:
1) What precautions do I need to take if I decide to give it a shot?

Don't loose any of the parts or cross thread the cover, no tools should be used anywhere in the process. Note when fully disassembled (for our purposes here) you will have 4 or 5 parts.

the main body
the rubber cover
the screw down cover
the diaphram ring & diaphram assembly (the thin ring may or may not be stuck to the outer edge of the diapharm)

2) I've seen how the tech twisted and wrestled the rubber cover to remove it. Is there a certain technique for this?

remember the D350 can be up to 20 years old, and has likely lost some of its strech and are prone to split from the corners around the switch. I try to remove them with a motion that will also loosen rather than tighten the screw down diaphram cover (pull on hose side first by sticking my thumb in the exhuast) then rock back and forth until it is off. No tools are needed for this step, if the rubber inside is lightly lubricated with silicone when reinstalling, it will make removal much easier next time.



3) After removal and inspection, when screwing back the diaphragm cover, how tight should this be? (hand-tight? finger tight?)

I would call it finger tight, the screw down cover is rather fragile, particularly around the ribs, care should be used when unscrewing it to not use excessive force, since it was recently serviced it should come off easily when grasped by the bare hand around the edge. Again don't cross thread.


4) Would I need to make other adjustments requiring tools and air tank?

No other adjustments should be needed, if it was assembled correctly, or close to correctly Remember the diapharm should be hooked on the lever, so after lifting the edge of the diaphram it will slide gently to the side to unhook.

5) Anyone have a diagram to illustrate how the diaphragm should sit on the case and other steps in the process?

Not on me, it is rather simple, but as always this is a do so at your own risk.

Thanks again.

p.s. note that when the set screw is changed the regulator may need to be retuned to get maximum performance.

 

[Isaac-1]

Here's a close-up of the set screw. A bit blurred. Could this last another year? It doesnt seem to be that bad now that I've looked at the close up but I could be mistaken.

It is hard to say, it certainly could last another year, or another 5 years, my biggest concern would be corrosion you can't see freezing it in place. If the tech did remove it, clean it and reinstall during the last service, this is less of an issue.

Ike

p.s. The question that comes to mind about your recent service, is what did the tech do, did he just clean the regulator, did he change any of the annual service parts at all?

 

[DA Aquamaster]

1. I have always found that running warm water over the cover helps it come off much easier and I have never cracked or done one when doing this.

2. Leave the Lp hose attached to the reg when you remove the cover - it prevents your hand florm slipping on the reg and gives you a bit more leverage. I shoudl add you do not put pressure on the hose or use it as a handle but rather use its presence on the inlet housing as an aid in stopping the reg from rotating in your hand while you pull off the cover.

3. Replacing the screw should not require removing or re-adjusting the poppet - but be sure the flat on the lever is properly seated on the top of the set screw.

4. The amount of slack in the lever needs to be just enough to ensure the reg does not freeflow with the diaphragm and cover installed. That varies a bit from reg to reg but generally about 1/16" to 1/8" of play in the lever is in the ballpark.

5. The assembly order is:
a. diaphragm (with the small bumps properly indexed to ensure the slot is aligned).
b. thin white or black anti-friction ring (prevents the cover from turnign the diaphragm when you tighten it)
c. Spoked screw on cover. (inspect to ensure there are no burrs on it that coudl damage the diaphragm) Just a bit beyond finger tight is fine.
d. THe rubber purge cover. Warming it up in hot tap water will help it go on smoother with less force required. .

 

[Couv]

In addition to the great advice you've gotten already, please ensure that if that is a self locking nut (usually nylon insert) at least one thread is engaged into the locking feature....hard to tell from the pictures, but it doesn't look like you have any threads into the nylock.

couv

 

[redacted]

In addition to the great advice you've gotten already, please ensure that if that is a self locking nut (usually nylon insert) at least one thread is engaged into the locking feature....hard to tell from the pictures, but it doesn't look like you have any threads into the nylock.

couv

There is a coating of blue "loctite"? on the threads of the screw so if it is threaded, then the locking feature is engaged.

7 Aug: I just looked again with a magnifying glass and that does look like the older style set screw with the nyloc insert just barely engaging which should leave the lever too loose. Probably worth a second look if you plan to dive that reg before it is properly serviced.

 

[ericpitar]

The question that comes to mind about your recent service, is what did the tech do, did he just clean the regulator, did he change any of the annual service parts at all?

It was completely dismantled and cleaned in ultrasonic cleaner. He stated the cleaning took longer than usual because of the set screw. Only the seat was changed per my request because the repair kit was just too costly. I'm already expecting a kit to arrive in a month or two but if you know where I can get repair kits for more reasonable price, please pm me. Hi did make some adjustments for the cracking pressure but didn't ask me to "test" it on the spot in dry land. Since breathing's significantly different on land vs. underwater, I did not bother to ask....Especially that a violent complete freeflow never even crossed my mind.

So bottom line, the original problem I had was the stuttering inhale before any service was done. After the initial service for that, I got a different and bigger problem which was the massive freeflow. This was "fixed" yesterday. Next step is to pool test to determine if the original stuttering inhale problem is fixed.

Thanks for the feedback!

e

 

[ericpitar]

I've just obtained a D350 schematic which better illustrates what this "slot" is. It looks like the inside end of the lever linkage....Correct? I'm hesitating to bother opening it now coz it looks like a tech would have to be a moron to not think of the importance of proper alignment on this....hmmmm....That said, I still may check it out if I get into a paranoid mode or thirst for some firsthand knowledge.

Thank you everyone for your feedback!!!!!

E

 

[redacted]

I've just obtained a D350 schematic which better illustrates what this "slot" is. It looks like the inside end of the lever linkage....Correct? I'm hesitating to bother opening it now coz it looks like a tech would have to be a moron to not think of the importance of proper alignment on this....hmmmm....That said, I still may check it out if I get into a paranoid mode or thirst for some firsthand knowledge.

Thank you everyone for your feedback!!!!!

E

Perhaps the tech did not think you would be diving it until all parts were received and it was properly serviced. After looking at the pic with a magnifying glass, I have to agree with couv. It looks like your set screw may be an older style with an embedded plastic plug that functions like a nyloc nut. The plastic plug looks to be barely engaged which would suggest the lever may be too loose (in both pics). The set screw on my D350 has about 1.5 threads showing. It's hard to tell if yours is much looser than that or if it is just the reflection from the chromed housing. A loose lever might explain the original problem of stuttering inhale.

 

[ericpitar]

Perhaps the tech did not think you would be diving it until all parts were received and it was properly serviced. After looking at the pic with a magnifying glass, I have to agree with couv. It looks like your set screw may be an older style with an embedded plastic plug that functions like a nyloc nut. The plastic plug looks to be barely engaged which would suggest the lever may be too loose (in both pics). The set screw on my D350 has about 1.5 threads showing. It's hard to tell if yours is much looser than that or if it is just the reflection from the chromed housing. A loose lever might explain the original problem of stuttering inhale.

I made it clear I intended to dive with it. Otherwise, I wouldn't have changed the seat at all and just waited for the entire annual kit to arrive.

I can't recall the exact sequence of events but I do remember him making an adjustment on the setscrew at one point and he may have done so after I took that photo. Here's another set but more close up showing before the lever correction and after. The initial closeup shot of the set screw in a previous post was taken from the "before" photo on this composite. The shot on the right may not be much help in counting the threads since it was taken at a slightly shallower angle as you'll probably notice.