Jerky air delivery on D400.

[elan]

Hi guys. have you ever had this kind of issue with the reg after reassembly.

I have serviced one of the D400s I have got recently, the reg was not completely clean with some traced of salt deposits on the metal parts of the body so I completely disassembled the reg, cleaned it up in the ultrasonic cleaner using vinegar solution and simple green, replaced all the o-rings (except the pre-dive switch, which turned out to be in a very good shape) I also replaced the poppet with the new one from the kit so the reg has received a completely new seat.

I followed the procedures published by DA Aquamaster and halocline and the reg tuned perfectly to 0.6 inch on the 2 cent magnehelic It happens to be inline with the CGF value as it bubbles very slow (1 bubble in 10 secs) when turned on the side and with the mouthpiece plugged and does not bubble at all in a normal diving position.

What happens is when I put the rubber cover on I get jerky air delivery when the reg is submerged and I inhale strongly although the delivery is OK without the cover and when inhaling normally.

There is very little play in the lever (just enough for the reg not to react to normal shaking) and the venturi is about halfway open.

I remember I had the same effect on my Air 1 when I put a new seat but it went away after a couple of dives. I have not had a chance to dive this specimen yet though.

The reg seems to be the older D400 (metal orifice and the lever has only one side shaved off)

Thanks a lot in advance

 

[DA Aquamaster]

Two thoughts:

1) Your venturi adjustment may be closed too much. Stuttering as you describe is a normal side effect of high airflow with no where to go. I like the venturi either fully open or just once click closed (which was the specified setting on the D400). Since you can see it through the mouthpiece and move it with something pointy, it's an easy adjustment to make.

2) If that does not resolve the problem, you can try adding just a bit more play in the lever.

 

[elan]

Thanks DA Aquamaster, I will try to play with the venturi and if it does not help I will try to increase the play in the lever (I guess that limits the flow as well).

What puzzles me that this does not happen when the rubber cover is not installed and the diaphragm is fully exposed. I guess it has something to do with the rubber limiting the water movement .

 

[Golan68]

Take out the cover and look at the diaphragm from the side if it's not too stretched forward. If yes see if the lever is flat. If it's flat try to flip it. All before giving more play [the last resort] I like it when there is no play, responsiveness and air delivery is much better, imwo.And, dear DA, do you have a list of all the orings needed for the Pilot? I didn't find any info so far. ​

---------- Post Merged at 06:49 PM ---------- Previous Post was at 06:47 PM ----------

one more thing, look that the pre dive position if it is not moving the lever forward

 

[elan]

The lever is installed as per the guide and it does not have much play and is not pushed forward by the predive switch. I tried giving it a bit of play but that did not help. Opening the venturi actually makes it worse. Im still to dive it to test completely in the field.

It still puzzles me that the effect only appears when the cover is on and does not apprear when its off.

 

[axxel57]

Did you check the membran?
If the lever is the old D350 style with only one side shaved off but the membran was changed for the newer D400 style with the bigger orifice for the lever there would be some play when the cover is touching the tip of the membran pin causing maybe those described effects.
Also, when the membran is pretty old the material wears out and the membran has no smooth surface anymore, it looks corroded and might also add some play which could cause some unusual play and therefore some sort of harmonics or jerky air delivery.
I would also have a look on the adjusting screw surface if you didn't change it. sometime with the years they are not completely smooth anymore and can cause strange behaviour.
Other thing, check also the exhaust valve by inhaling relatively strong with the air turned off.
I had to change three exhaust valves recently because they would flip into the exhaust tee, causing air to get through. I think that is more a problem of the old D300 & D350, but checking is a good idea anyway. The new exhaust valves are much thicker and stronger than the old ones.
Thanks for reading.

---------- Post Merged at 09:15 AM ---------- Previous Post was at 09:13 AM ----------

Sorry, I meant the surface of the membran might look corrugated, not corroded.

 

[elan]

Axxel I will check the screw as I have not changed it, I should have a kit with the screw which I can install. The membrane and the exhaust valve looked in a good shape, the reg seems to pass the sucktion test , thanks a lot for all the hints.

 

[axxel57]

Elan, I'm not sure if you understood one part of checking the membran.
The linkage for the lever has has a different diameter depending on the D model. So you cannot put the latest D400 lever into the linkage of a D350 membran bececause the lever diameter is too wide. The other way around it is working, but the lever would have quite some more play.
I was thinking that if over the time a former owner has changed the old membran with the small linkage for the newer D400 membran with the bigger linkage but kept the old lever style in the 2nd stage, there could be maybe too much play for the lever within the linkage causing that strange behavior at high airflow. The lever must have very little play in the linkage.
I don't know if SP made this changes in a way that the old lever style is interchangeble with the new membran linkage. I would check that anyway.
You got the SP repair guide for the D400?
Thanks for reading.

 

[elan]

Axxel yes I got you. If i rmember correctly the level had no play in the membrane connection but I will check it when Im back home

 

[elan]

I was finally able to take the reg for a dive today after it was sitting on the shelf for a couple of weeks, The reg was working well with no bad effects