Is this crazy or will it work??

Is this crazy or will it work??

Joined: November 5th, 2008, 8:23 pm

April 30th, 2017, 4:34 am #1

I have a slow leak on my benjamin discovery.
I've listened and don't hear any "hissing" or releasing of air.
I've taken it apart and replaced all the o-rings in the pressure tube.
The two on the front side of the valve, the two around the gauge block, and the one at the filler end.
I also replaced the little o-ring underneath the pressure gauge.
And it still has a slow leak.
I'm thinking one of two places.
Either the check valve in the foster fill fitting, or the exhaust valve?
I can't really check the exhaust valve short of replacing either it or the entire valve assembly.
But I did have a thought how to check the foster fitting.
Could I not take a kids party balloon and fix it around the filler port with a zip tip or something and then see if the balloon expands over a short period?
Would this not tell me if it got a slow leak there?
Thanks
Ray
Last edited by ray1377 on April 30th, 2017, 4:36 am, edited 1 time in total.
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Joined: November 28th, 2002, 6:26 pm

April 30th, 2017, 4:40 am #2

The old standby of soapy water would probably work better. If you go the balloon route, why not also put one over the muzzle (with the bolt closed) to check the exhaust valve?

But in any case, don't forget that Crosman pressure gauges are a frequent source of leaks.
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Joined: November 5th, 2008, 8:23 pm

April 30th, 2017, 5:01 am #3

I'll give that a try and see what happens.
Thanks
Ray
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Joined: June 11th, 2002, 12:12 pm

April 30th, 2017, 10:03 am #4

I have a slow leak on my benjamin discovery.
I've listened and don't hear any "hissing" or releasing of air.
I've taken it apart and replaced all the o-rings in the pressure tube.
The two on the front side of the valve, the two around the gauge block, and the one at the filler end.
I also replaced the little o-ring underneath the pressure gauge.
And it still has a slow leak.
I'm thinking one of two places.
Either the check valve in the foster fill fitting, or the exhaust valve?
I can't really check the exhaust valve short of replacing either it or the entire valve assembly.
But I did have a thought how to check the foster fitting.
Could I not take a kids party balloon and fix it around the filler port with a zip tip or something and then see if the balloon expands over a short period?
Would this not tell me if it got a slow leak there?
Thanks
Ray
Or you stuff the front of the gun in a bucket of water and watch to see where the bubbles come from it should not be difficult to figure out what is leaking then.
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Joined: November 17th, 2006, 3:51 am

April 30th, 2017, 3:05 pm #5

I have a slow leak on my benjamin discovery.
I've listened and don't hear any "hissing" or releasing of air.
I've taken it apart and replaced all the o-rings in the pressure tube.
The two on the front side of the valve, the two around the gauge block, and the one at the filler end.
I also replaced the little o-ring underneath the pressure gauge.
And it still has a slow leak.
I'm thinking one of two places.
Either the check valve in the foster fill fitting, or the exhaust valve?
I can't really check the exhaust valve short of replacing either it or the entire valve assembly.
But I did have a thought how to check the foster fitting.
Could I not take a kids party balloon and fix it around the filler port with a zip tip or something and then see if the balloon expands over a short period?
Would this not tell me if it got a slow leak there?
Thanks
Ray
They do make industrial/commercail leak detection stuff...and basically NONE of us has that laying around.

If you got little kids, may have some bubble making stuff (those little plastic bottles with the plastic ring to blow though from the Dollar store?).

If not, we pretty much all have water and some form of soap.

YEah...water freaks airgunners out. Not sure why, it's not as if a pressurized system is going to suck stuff in, and we manage the "art of drying" every time we take a shower.

I count 8 places you'd need to cheack for "static" leaking (leaking while it's just sitting there)but only 7 of them are easy to get to.

Basically everwhere there is a sealed opening or sealed joint to the outside world.

1. Leak from the muzzle (if the bolt is closed) is the valve stem seal not sealing.
2. Leak from the open end of the fill nipple is the little o-ring inside the fill nipple not sealing.
3. Can leak from the threads of the nipple into the end cap.
4. Can leak at the joint of the end cap and the air tube.
(the next 3 are right next to eachother, so will need to really look closely to tell which is leaking)

5. Can leak from the back of the gauge itself (there is a little hole on the back face of the gauge...if it bubbles out of that, you need a new gauge).
6. Can leak from the threaded shank of the gauge were is screws into the gauge block inside the tube.
7. Can leak from the opening in the tube that the gauge's shank passes through to get to the gauge block. That gauge block has an o-ring on each side of that hole that often go bad.

8 (The harder one). Could leak out the back end (striker end) if the o-rings that seal the valve to the tube or the o-ring that seal the two halves of the valve go bad. To check that, are going to have to take the rifle apart becasue we need to check around the rear of the valve/air tube.

USUALLY, will find that if the o-rings on the valve body leak, will find a little bubbling at the two valve retetion screws in the side of the air tube, the front trigger housing screw...but those may not show a slow leak (air taking the easiest passage out, which is along the sides of the valve to the back).

So, out the stock...barrel band off...reciever and barrel off...pluck out the transfer port parts so you don't lose them...rear end cap, striker and striker spring out...now you can look down into the rear of the tube and see the back of valve. It's still retained by all the fixation screws, so you can gas it up for a leak check aound the rear end of the valve.


THE TRAP:

Stopping at the first leak you find?

What we (myself included) often do is detect a leak, fix it, and then get POed that the thing still leaks.

Well..there is no rule saying that there has to be just one leak, but we (myself included) stop checking once we find the first one (especially it is one of the simple ones to fix).

We might even have been right and there was only one leak...but we created a new leak while fixing the first one.
Last edited by gubb33ps on April 30th, 2017, 3:08 pm, edited 1 time in total.
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Joined: November 5th, 2008, 8:23 pm

May 1st, 2017, 2:07 am #6

getting an airgun or any gun for that matter wet, let alone dunking it under water.
But that would be one sure fire way to find a leak.
Thanks
Ray
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Joined: June 25th, 2002, 1:34 pm

May 1st, 2017, 11:46 pm #7

I have a slow leak on my benjamin discovery.
I've listened and don't hear any "hissing" or releasing of air.
I've taken it apart and replaced all the o-rings in the pressure tube.
The two on the front side of the valve, the two around the gauge block, and the one at the filler end.
I also replaced the little o-ring underneath the pressure gauge.
And it still has a slow leak.
I'm thinking one of two places.
Either the check valve in the foster fill fitting, or the exhaust valve?
I can't really check the exhaust valve short of replacing either it or the entire valve assembly.
But I did have a thought how to check the foster fitting.
Could I not take a kids party balloon and fix it around the filler port with a zip tip or something and then see if the balloon expands over a short period?
Would this not tell me if it got a slow leak there?
Thanks
Ray
remove the hammer and spring, fill the tub or sink with water, submerge the action, and see where the bubbles come out. The action is pressurerized water will not enter it. hth.
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Joined: November 17th, 2006, 3:51 am

May 2nd, 2017, 12:25 am #8

getting an airgun or any gun for that matter wet, let alone dunking it under water.
But that would be one sure fire way to find a leak.
Thanks
Ray
...not a Crosman in this case, a BAM 51, but it pretty well localized the leak. (yep...dowdy seals can go bad).

Under 2.5" of hot water.




HOT WATER is the key here (no little ones here, so the hot water is hot...like 180-185F)...dry it with a towel, "fling-n-sling" the tube, (if you have compressed air to blow out the little creases, all the better) and it's dry in about 2 minutes.
Last edited by gubb33ps on May 2nd, 2017, 12:27 am, edited 1 time in total.
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Joined: November 5th, 2008, 8:23 pm

May 2nd, 2017, 3:16 am #9

I have a slow leak on my benjamin discovery.
I've listened and don't hear any "hissing" or releasing of air.
I've taken it apart and replaced all the o-rings in the pressure tube.
The two on the front side of the valve, the two around the gauge block, and the one at the filler end.
I also replaced the little o-ring underneath the pressure gauge.
And it still has a slow leak.
I'm thinking one of two places.
Either the check valve in the foster fill fitting, or the exhaust valve?
I can't really check the exhaust valve short of replacing either it or the entire valve assembly.
But I did have a thought how to check the foster fitting.
Could I not take a kids party balloon and fix it around the filler port with a zip tip or something and then see if the balloon expands over a short period?
Would this not tell me if it got a slow leak there?
Thanks
Ray
put the balloons on her this evening.
I'll check it in the morning before work.
I hope it works. If it doesn't, I'll be giving her a "HOT" bath.
Thanks for the info fellows.
Ray
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Joined: October 14th, 2006, 12:30 am

May 2nd, 2017, 10:40 am #10

I have a slow leak on my benjamin discovery.
I've listened and don't hear any "hissing" or releasing of air.
I've taken it apart and replaced all the o-rings in the pressure tube.
The two on the front side of the valve, the two around the gauge block, and the one at the filler end.
I also replaced the little o-ring underneath the pressure gauge.
And it still has a slow leak.
I'm thinking one of two places.
Either the check valve in the foster fill fitting, or the exhaust valve?
I can't really check the exhaust valve short of replacing either it or the entire valve assembly.
But I did have a thought how to check the foster fitting.
Could I not take a kids party balloon and fix it around the filler port with a zip tip or something and then see if the balloon expands over a short period?
Would this not tell me if it got a slow leak there?
Thanks
Ray
If the valve stem isn't sealing well it will leak. That was the culprit on my hpa'd 2260.
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