Moved this post to here from the General area: 880 leaking air

[airgunaut]

Since late July my shots have intermittently been bizarre. Like too far off to be Just Me. But as I said, it was intermittent. I automatically blamed it on myself until this morning, when yet again the first couple of shots were excellent, like make-me-very-happy accurate, shooting anywhere from 37’ to 50’ standing offhand.

But it was a problem with the 880 after all. Today I actually heard hissing from the rifle when I pumped, but only sometimes. I had not heard that before.

I replaced the o-rings only 6 months ago! During that time, the gun didn’t make any leaking sounds but it wouldn’t retain air for more than a little time after pumping. This time, the gun sometimes holds air well and then it just stops doing so on the next attempt at pumping. Then reverts to holding some air, etc etc. Pulling the trigger only results in a CLICK, and the pellet remains in the gun. I tried adding more pumps and fired it to clear the pellet, which shot weakly, slowly, with a POP much quieter than normal.

The gun is lying in ignominy right now, till I feel motivated to open it up. I did not like repairing it back then and am not looking forward to the process again, such a short time afterward. Shouldn’t the thing work well for more than 6 months?

I have a complete piston assembly (? name) with the elastomer keg etc, plus an abutment assembly and an extra chamber seal that Daisy sent before. I don’t have a bunch of o-rings around, so I’ll open it up only after buying some of those, because I might as well replace those while the thing is disassembled.

[Ronno6]

Mr. Pat,
Where do you hear the hissing?
If out the barrel or loading port with the bolt open, your problem is most likely the exhaust valve.
Put a balloon over the end, cock and close the bolt, and see if air leaks into the balloon....
I would consider that for an intermittent problem.
Otherwise it could be the chamber seal or the O-ring that seals the pump tube to the valve body.

Make sure that your pump tube is not moving when you pump the arm.
Possibly your tube (aluminum I am assuming...) may sometimes be riding up over the retaining indentation
in the top of the pump frame. If that is moving intermittently, that could cause the problem.

The piston assembly should not be part of the problem.....

[airgunaut]

I heard the hissing from what sounded like the receiver bottom.***

Sometimes it hisses upon pumping and sometimes not. Several times now I gave it a pump or two and listened (no hissing), then closed the bolt and dry-fired. Each time there was a pop of released air. Very unpredictable, erratic behavior. As if something is randomly sitting tight and other times opening or moving in a way that lets air escape.

I’ll have to buy balloons when I next go into town. None on hand. I might try tightly rubberbanding a plastic bag over the muzzle meanwhile. From what happened this morning, the air escapes before the trigger is pulled, sometimes in part and sometimes ALL the pumped air.

When I replaced the o-rings earlier this year, I cleaned and inspected the abutment assembly (the chamber seal looked and felt like a new one). I took apart and cleaned the exhaust valve assembly. The little white sphere thingie (poppet?) looked like new. I replaced the tiny o-ring.

The pump tube is aluminum.


***Just now I test pumped it again. I got the gun to hiss this time. Sounded like air came out the loading port, alright. I pumped some more and quickly put my finger over the port, which changed the sound and volume of the escaping air. When I closed the port and fired, there was still enough air to make a pop.

Oh, BTW, I am a Ms./Mrs.

[Ronno6]

Oh, BTW, I am a Ms./Mrs.

Well, that answers the age old SNL question.......
My Apologies......

Sounds like exhaust valve.......

[caudie]

I'd do an alcohol flush before I took it apart.  Could be just a little crud in there.

[airgunaut]

Oh, BTW, I am a Ms./Mrs.

Well, that answers the age old SNL question.......
My Apologies......

Sounds like exhaust valve.......

Trying to make that weird Pat the It sound…ih ih ih ih ih ih.

Monday I’ll order a new exhaust valve assembly and a set of o-rings from Daisy. I did the hiss check again and now it is happening more often. It sounds sort of fizzy with only one or two pumps.

[Ronno6]

Hope I'm right, then. Fingers crossed.........

[Ronno6]

Have you tried putting a drop of oil where the exhaust valve stem exits the retainer bar?
There is an O-ring just inside that can be causing the stem to stick a bit....

[airgunaut]

Hope I'm right, then. Fingers crossed.........

If the leak is caused by something else, I’ll have a spare exhaust valve assembly, not a bad thing. I’m not opening up the gun until I have the part on hand and time to dedicate to fixing it. I don’t have space to leave it in pieces on top of my table/desk.

[Ronno6]

I would give the oil a try...easy enough to do.

[airgunaut]

I would give the oil a try...easy enough to do.

Hmmm, maybe. ND 30 wt? I do wonder if the big increase in humidity the last few weeks has anything to do with this intermittent weirdness. Normally it is really dry in this area.

[Ronno6]

I would give the oil a try...easy enough to do.

Hmmm, maybe. ND 30 wt? I do wonder if the big increase in humidity the last few weeks has anything to do with this intermittent weirdness. Normally it is really dry in this area.

That would do nicely if you have it......or Pelgun oil....

[airgunaut]

Last night I again pumped two strokes and dry fired the 880. First shot, no hissing heard, shot sounded normal. I knew not to think the gun had healed itself. 😆

Second attempt at pumping, the hissing started. It is coming from both the loading port and the muzzle. When I pulled the trigger, the sound was weak unless I quickly added more pumps.

It felt like the pump arm moved a tad laterally when I did the second attempt, as if there is play somewhere. Could I have literally worn out some part?!!!??

This matches what was happening when I would start practicing. The first couple of shots might go normally, and then the gun acted shortwinded.

I picked up a new valve assembly kit and o-ring seal kit in the mail yesterday. Need to re-view the videos I watched 6 months ago and make a new screw location template. And dedicate a temporary work area. It’s not happening this weekend, except maybe rewatching the videos and making the template.

[caudie]

I would say it's the valve assembly.  I don't think in worn or you wouldn't get a normal shot out of it.  Probably sticking a little.

Put a 1/4 teaspoon of alcohol just ahead of where you oil with the muzzle up.  Let it sit a minute or 2 then pump 1 or 2 times and shoot into a folded up towel.  Pump and discharge into the towel until it stops discharging any mist.  Put 3 or 4 drops of oil same way you do the alcohol and pump and discharge into the towel.  Then try it and see if it works more normal.  If you can get a few normal shots and it sticks again repeat above.

Nothing to lose if you're going to tear it down and replace seals and valve anyway.  You might be surprised. 

[airgunaut]

 

I would say it's the valve assembly.  I don't think in worn or you wouldn't get a normal shot out of it.  Probably sticking a little.

Put a 1/4 teaspoon of alcohol just ahead of where you oil with the muzzle up.  Let it sit a minute or 2 then pump 1 or 2 times and shoot into a folded up towel.  Pump and discharge into the towel until it stops discharging any mist.  Put 3 or 4 drops of oil same way you do the alcohol and pump and discharge into the towel.  Then try it and see if it works more normal.  If you can get a few normal shots and it sticks again repeat above.

Nothing to lose if you're going to tear it down and replace seals and valve anyway.  You might be surprised.

I oil the foam wiper donut (plus hinge points when needed). Is that where you’re saying to put isopropyl alcohol on?

[caudie]

No need to put alcohol on the wiper.  Just drop it in on the Elastomer close to the compression tube end and let it run in.  Same with the oil after you pump and shoot into the towel.  Then when you get no more mist coming out oil the wiper good.

[airgunaut]

Have you tried putting a drop of oil where the exhaust valve stem exits the retainer bar?
There is an O-ring just inside that can be causing the stem to stick a bit....

Just want to make sure I understand what spot to lube. In the attached photo, would the oil be applied at A, B, or C? Sorry if this is a dumb question.



I think I’ll try the alcohol flush first, as Caudie recommended. No disassembly, and I can leave the scope on it.

If that doesn’t fix the leak, then I’ll remove the scope, open the exterior, and try oiling the stem. I remember there was a tiny o-ring that I replaced after removing the valve assembly and cleaning the recess.

If that still doesn’t work, I have a new valve assembly, a new abutment assembly, and a new o-ring seal kit.

Fervently hoping the alcohol flush takes care of it.

[Ronno6]

Oil at location "A" where the metal stem exits the metal brace.
Turn the valve body on its back, cock the sear, apply a drop of oil, then fire.
This will work the oil into the O-ring inside.

[airgunaut]

Oil at location "A" where the metal stem exits the metal brace.
Turn the valve body on its back, cock the sear, apply a drop of oil, then fire.
This will work the oil into the O-ring inside.

Thanks! Worth trying as Plan B.