Question JetStream Woes: Need Advice!

[Njord fr]

Hey everyone,

Today, I ran into an issue with my Poseidon Jetstream second stage getting stuck in free flow just before my dive when I opened my tank.

I had to switch to another regulator because it wouldn't stop, even with the usual trick of putting my finger in or blowing into it. So, I closed the tank, attached a reliable old Cyclon 5000 regulator, and went ahead with my dive.

After coming out of the water, I figured I'd still take a look at it. Even after an hour's rest, when I opened the tank, it went straight back into free flow mode.

I tried it with another Jetstream second stage regulator, and it worked fine, ruling out any issues with the first stage.

I've disassembled, cleaned, and everything, but it hasn't made any difference.

Any advice?

Thanks !

 

[Geo7]

The only time this happened to me was when the whole reg froze over between ice dives. I just thawed it and it worked (you can tell I like Jetstreams).

Back to your question, Bigbella and Rsingler will chime in with more info, but to help (them) diagnose, let's start with the intermediate pressure: Can you measure the IP of the first stage?

 

[Bigbella]

Coincidentally, I was recently working on a Jetstream that was just short of free flow; and it was an issue with a carelessly loosened valve tube, which allowed settings to “drift.” That tiny screw actually has a purpose -- who knew?

A worst case scenario, could be a damaged servo valve, which once did that very same thing, regardless of what I did to stop the flow; it doesn’t really take that much effort to trash it. Further, a damaged sleeve ("condom") on the LP valve or even a blockage of the same, can also cause a free-flow, at least according to the old troubleshooting guides.

Out of curiosity, are you able to pressure test the whole LP valve without the regulator housing; and does it still blow? I keep both a sawed-off section of an old Jetstream housing with the threaded portion intact, to mount the valve on a hose. @Fibonacci came up with an elegant solution for that -- a modern take on an old discontinued tool (see below), which allows for the examination of the entire pressurized LP valve -- and not just the servo tip, of a disassembled housing (minus, say, the cover and diaphragm, etc). A leak can occur elsewhere.

How recent was its last servicing, since spent o-rings can also prove to be a problem?

Could even be a simple issue with your purge button and its spring or maybe your IP setting?

 

[runsongas]

if you have already ruled out the predive switch and a hose issue causing it not to close the servo correctly, then its time to take it apart and check the servo.

 

[buddhasummer]

@Fibonacci

 

[pintafish]

You can take the exhaust cover & diaphram off, turn your tank on and test to see if it still free flows. If you put it in water, you can check to see if your servo valve is leaking. Then you will know whether it needs to be retuned or parts replaced.

 

[Njord fr]

Hello everyone,

Well, I’ve compiled all the responses and having another jet stream, I was able to dismantle everything and test by deduction.
My attention quickly focused on the Servo tip, which was malfunctioning on one or the other of the two Jetstreams.
I looked inside, didn’t see any particular dirt, I operated it manually for a bit with my finger, wiped it off… in short, after reassembling, it works…
I don’t really have any conclusion to bring apart from everything I’ve just explained…
This jetstream in particular has been serviced three month ago.
Thank you all!

 

[Alex Ouroboros]

Coincidentally, I was recently working on a Jetstream that was just short of free flow; and it was an issue with a carelessly loosened valve tube, which allowed settings to “drift.” That tiny screw actually has a purpose -- who knew?

A worst case scenario, could be a damaged servo valve, which once did that very same thing, regardless of what I did to stop the flow; it doesn’t really take that much effort to trash it. Further, a damaged sleeve ("condom") on the LP valve or even a blockage of the same, can also cause a free-flow, at least according to the old troubleshooting guides.

Out of curiosity, are you able to pressure test the whole LP valve without the regulator housing; and does it still blow? I keep both a sawed-off section of an old Jetstream housing with the threaded portion intact, to mount the valve on a hose. @Fibonacci came up with an elegant solution for that -- a modern take on an old discontinued tool (see below), which allows for the examination of the entire pressurized LP valve -- and not just the servo tip, of a disassembled housing (minus, say, the cover and diaphragm, etc). A leak can occur elsewhere.

How recent was its last servicing, since spent o-rings can also prove to be a problem?

Could even be a simple issue with your purge button and its spring or maybe your IP setting?

Can you believe only in the last week with having trouble fault finding on an exstream I came to the same conclusion as finding an old knackered housing and literally cutting everything off apart from the necessities for attaching the hose as couldn’t correctly diagnose servo, or servo to next part at fault… a great idea though!!

 

[Bigbella]

Can you believe only in the last week with having trouble fault finding on an exstream I came to the same conclusion as finding an old knackered housing and literally cutting everything off apart from the necessities for attaching the hose as couldn’t correctly diagnose servo, or servo to next part at fault… a great idea though!!

Here are a couple of those tools — the yellow one, just a sawed-off piece of an old Jetstream; and the other, @Fibonacci’s modern take on the original Poseidon tool (2894), which allows for both newer and older LP valves, some of which will not fit over the ABS alignment “pins” (which can just be filed off) in newer housings.

For whatever reason, Poseidon no longer requires water testing of valves, with the notable exception of the Jetstream PP, for their Atmosphere full face mask.

I’ve always done the water testing with each model, and would still encourage it . . .

 

[Alex Ouroboros]

Here are a couple of those tools — the yellow one, just a sawed-off piece of an old Jetstream; and the other, @Fibonacci ‘s modern take on the original tool, which allows for both newer and older LP valves, some of which will not fit over the alignment “pins” (which can just be filed off) in newer housings.

For whatever reason, Poseidon no longer requires water testing of LP valves, with the exception of the Jetstream PP, for their Atmosphere fill face mask . . .

Thanks for that clarification