More DAR bad luck

[Rat Sniper (AKA: PaulT58)]

Interesting, if the poppet wasn't seating and it was leaking wouldn't you see bubbles from the end of the barrel?

[kingrude1]

Interesting, if the poppet wasn't seating and it was leaking wouldn't you see bubbles from the end of the barrel?

yes you would. It was leaking slowly at first. This time when I aired it up it was leaking much more rapidly. Took the poppet stem out, then  the brass guide, brass guide had a gouged place on the bottom, wondering if that material is whats in there causing it not to seal? Cleaned and put it back together, aired it up, and now there's no noticeable leak, will let it set overnight to see if it losses air.

[tracker1955]

Yep, air can't get there unless it's going past the poppet in the valve. How does it look around the valve stem, could it be sticking partially? Don't remember who had said it but one of our guys was having problems with the valve because it was dry fired and bent the brass around the stem causing it to stick. I would empty the air so you can get a better look at the valve without air pressure being on it.

[tracker1955]

Posted at the same time, glad you found it, hope it holds for you.

[kingrude1]

Yep, air can't get there unless it's going past the poppet in the valve. How does it look around the valve stem, could it be sticking partially? Don't remember who had said it but one of our guys was having problems with the valve because it was dry fired and bent the brass around the stem causing it to stick. I would empty the air so you can get a better look at the valve without air pressure being on it.

See above Tom, this is exactly what I did. There was a gouged place on the brass guide, I am thinking that material is what is in there causing the poppet not to seat. Hopefully I got it out.

[Rat Sniper (AKA: PaulT58)]

I asked because when I was checking for leaks earlier today I put a microfiber cloth soaked in soapy water over the end of the barrel with a rubber band to hold it in place and there were no bubbles at all.  No bubbles anywhere else either, but it's still losing air.  I suspect it will be empty by morning, so I may tear it down and look at the valve as well. 

[kingrude1]

We are all learning together Paul. Before I wasn't taking the valve out the block and using on the tube, doing this made it easier to find, well that and the fact my leaking had gotten much worse.

[Rat Sniper (AKA: PaulT58)]

We are all learning together Paul. Before I wasn't taking the valve out the block and using on the tube, doing this made it easier to find, well that and the fact my leaking had gotten much worse.

I'm doing a ballon test on the end of the barrel.  If the valve is leaking, it should inflate the ballon, right?

[kingrude1]

Yes it should inflate the balloon. Had a thought, if you have a slow difficult to find leak, would it cause any harm to the tube if you just submerged it in water? With the pressure pushing outward I don't see how it could, of course you would want to dry and oil the valve & fill end afterwards.

[Rat Sniper (AKA: PaulT58)]

Yes it should inflate the balloon. Had a thought, if you have a slow difficult to find leak, would it cause any harm to the tube if you just submerged it in water? With the pressure pushing outward I don't see how it could, of course you would want to dry and oil the valve & fill end afterwards.

I thought about doing just that.  I’d have to fill the bathtub, it’s the only thing big enough.  I guess I could also fill a bucket and just dip one end and then the other and see if there are any bubbles. I’ll see if the barrel ballon is inflated in the morning, so far it hasn’t filled at all.  There’s 200 bar worth of air in the tube, it’s got to be going somewhere!

[tracker1955]

Air is like water in that it will take the route of least resistance to get out.

[TheSaint]

I'm the guy who told you not to EVER dry fire this rifle, as it will pinch the striker rod holder closed around the striker rod itself. Please read on if unsticking the striker rod holder doesn't stop the leak....

If you've got a leak, and have no signs of air escaping around the regulator, end caps, or gauge, you may need to increase the tension on the poppet valve spring. Take the air tube off the poppet housing. You will see a metal compression disc with four holes in it. Tighten it down untill the leak at the transfer port stops. I had to turn mine in  untill it was close to 6mm deep from the top of the poppet valve housing. This also decreases your dwell time, so any tuning you've done is gonna have to be re-done.

That metal disc is what the poppet valve spring sits against. It's a terrible design, as the spring is not pinned in place by anything. The spring can migrate around the inside radius of the poppet valve chamber at an angle not straight on to the poppet valve and cause the cheap plastic poppet valve to not seat, or break. Ask how I know.

Also, that tension disk will walk itself out of the chamber over time. Lock-tite would have solved this, but as I said before, the design is completely FUBAR. You need to improvise a holding pin for the spring, and also put a thrust washer on the poppet valve where the super stiff, unfinished end, sharp as a knife, METAL poppet valve spring sits on the super-duper cheap, PLASTIC poppet valve itself. Like I said, the design is just wretched.

[kingrude1]

Yes it should inflate the balloon. Had a thought, if you have a slow difficult to find leak, would it cause any harm to the tube if you just submerged it in water? With the pressure pushing outward I don't see how it could, of course you would want to dry and oil the valve & fill end afterwards.

I thought about doing just that.  I’d have to fill the bathtub, it’s the only thing big enough.  I guess I could also fill a bucket and just dip one end and then the other and see if there are any bubbles. I’ll see if the barrel ballon is inflated in the morning, so far it hasn’t filled at all.  There’s 200 bar worth of air in the tube, it’s got to be going somewhere!

The problem with the barrel balloon as I thought about what mine was doing is that air will escape also from breach around the bolt probe too, might not go down the barrel to the balloon. I did as you said last night, took me a cup deep enough, put water in it and submerged each end of the air tube in it, saw no bubbles. Doesn't appear any air is missing this morning, will wait till this evening and check again, at this point I am so gun shy I just expect it to fail at any moment.

[kingrude1]

I'm the guy who told you not to EVER dry fire this rifle, as it will pinch the striker rod holder closed around the striker rod itself. Please read on if unsticking the striker rod holder doesn't stop the leak....

If you've got a leak, and have no signs of air escaping around the regulator, end caps, or gauge, you may need to increase the tension on the poppet valve spring. Take the air tube off the poppet housing. You will see a metal compression disc with four holes in it. Tighten it down untill the leak at the transfer port stops. I had to turn mine in  untill it was close to 6mm deep from the top of the poppet valve housing. This also decreases your dwell time, so any tuning you've done is gonna have to be re-done.

That metal disc is what the poppet valve spring sits against. It's a terrible design, as the spring is not pinned in place by anything. The spring can migrate around the inside radius of the poppet valve chamber at an angle not straight on to the poppet valve and cause the cheap plastic poppet valve to not seat, or break. Ask how I know.

Also, that tension disk will walk itself out of the chamber over time. Lock-tite would have solved this, but as I said before, the design is completely FUBAR. You need to improvise a holding pin for the spring, and also put a thrust washer on the poppet valve where the super stiff, unfinished end, sharp as a knife, METAL poppet valve spring sits on the super-duper cheap, PLASTIC poppet valve itself. Like I said, the design is just wretched.

Thanks Mike you are a wealth of knowledge on how these things go together and are suppose to work.

[Rat Sniper (AKA: PaulT58)]

This info is very helpful.  I think I'll tear into it again today and have a look at the valve and see if it's leaking.  No air in the ballon this morning, but lost about 40 Bar of air overnight, so it may be exiting at the bolt probe if my leak is at the valve like yours.  Hopefully yours will still be holding air tonight.  Thanks to David, Tom and Mike, we may figure these things out after all!

[Rat Sniper (AKA: PaulT58)]

I may have found the source of my leak!  Based on Mike's comments and Tom's findings, I disassembled the valve to have a look at what was going on.  The first thing I noticed was both the retaining disk Mike talked about and the brass poppet valve guide were very loose! 

I removed both and pulled the poppet to see if there was debris like Tom found, thankfully, there wasn't.  But, the plastic poppet head sure wasn't square on the end of the shaft and since it's a very hard plastic, I suspect it is not seating evenly and that's where the leak is coming from. 

I reassembled it, tightened the brass valve guide and applied a drop of blue locktite to the retainer disk and snugged it up against the spring.  It could have gone much further, but I have no idea how tight it really needs to be.

I aired it back up to 200 Bar and put my rubber glove finger over the end of the valve and the transfer port and am letting it sit to see if it fills the finger with air.

I e-mailed Ryan also and sent him the picture of the poppet, hopefully, they have some spares and he can send me one that sits square on the shaft when he sends the o-rings.  It would be great to get this resolved!

[kingrude1]

Well I am almost afraid to say it but the Dar.25 is holding air. Got home from work and it was still at the same pressure I filled it to yesterday 170-180 bar, wasn't able to get a 200 bar fill because tank is low. Mounted scope and now to see what happens when I shoot tomorrow. Already having remorse for not disassembling down to the poppet before putting back together, we shall see what happens, used my other tank to finish filling to 200 bar and let it sit again overnight.

[Rat Sniper (AKA: PaulT58)]

That is encouraging news David!  Mine was still holding air this afternoon so I ran two magazines of H&N Sniper Mediums through it.  It dropped from 200 Bar to about 170 Bar, so I should easily get 3-4 magazines on a fill.  I topped it off and will let it sit overnight and see what it looks like in the morning.  I wonder if the loose retainer plug and valve guide had more to do with the leak than the o-rings?

While I had it apart this morning, I put some RWS Chamber oil on the contact points in the trigger assembly.  I haven't mustered enough courage to take it apart to polish the contact surfaces, so I thought the oil would help some, and it did.  The trigger was much smoother.  Accuracy is getting better too.  I was getting 1" groups at 50 yards.  If I can get the leaking under control, this should prove to be an exceptional air rifle!

[kingrude1]

Glad to hear you are seeing some success to Paul, I think we were do something other than frustration for a change. Aired mine up totally to 200 bar and it is still holding there, mounted me a scope and hoping to get outside with it tomorrow and run me some magazines through it while I site it in.

[Gertrude]

i realize this reply is late, but I highly doubt a balloon over the barrel (shroud) would fill with air from a poppet leaking.
This is because I also highly doubt the shroud is air tight around the breech end of the barrel.
 just food for thought.