GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: SpeedyBB on August 31, 2020, 07:42:41 PM
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Hey long time no post. So I was shooting my Marauder today, and suddenly one shot sounded too weak and quiet, next shot same thing happened. Third shot it didn't even shoot the pellet which is now stuck half way down the barrel. Removed the magazine and checked the air pressure gauge, double checked by hooking it to my pump, it definitely has 2,900 psi. Shot it a couple more times with no magazine and still nothing. So I disassembled it and found the issue, the valve pin appears to be stuck, you can see where the hammer struck the valve body. Picture is attached. The black dust is graphite powder, I cleaned and added some more last summer. Somehow air is not rushing out, but I don't think it snapped off since there were clearly two anemic sounding shots then the third which didn't even fully shoot the pellet down the barrel. A break off should have happened all at once don't you think? Maybe it is a break though, I am puzzled. If it did break I don't know where the pin is. If it is currently leaking it is very slow, I will update the status of the pressure later.
So clearly it's going to need a new valve. But how do I get the air out? Should I just loosen the gauge a little or something? Valves are out of stock on pyramydair until the 29th, too bad. But maybe I will find one somewhere else. The valve is the only thing I have not had out of the gun, but it looks easy. For now the gun is reassembled. Pellet still stuck in the barrel.
So maybe it being flush without all the air coming out is impossible and it snapped, I haven't looked to see what the inside of the valve looks like though. But the picture doesn't look like a break at all.
EDIT
Picture size is too big and I am on my phone. Hang on I will need to shrink the file size from my computer.
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Here is the picture. Same picture but I added a second which is zoomed in. Doesn't look broken to me.
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I suspect the poppet stem punched through the delrin poppet head. You might not need a whole valve, just a poppet.
I think the best price for complete valve assy is from crosman, but you have to call them with the part number.
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Yea would say fractured poppet ... But also looking at picture it sure looks like some serious hammer striker contact with valve !!
And valve looks modified too not looking stock around the poppet stem in general ???
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I agree with John, definitely poppet. Crosman part number - 1700-140, $1.70 each when I ordered in December. I would get a couple. $4.00 shipping.
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Thanks for the replies. Yeah I figured it might have pushed through some sort of seal in order for it not to be leaking. Has anyone seen this happen before? It's not even tuned for power, three turns on the preload and 3.5 on the stroke.
Motorhead, this is a stock valve, got the gun directly from Crosman about two years ago now. Were they different on earlier models?
So to release the air should I loosen the gauge a tiny bit? And what about the amount of damage the brass valve body took. Is it thick and heavy enough for that to make no difference? That was not a lot of hits, only a few. I didn't keep shooting it.
This might be time to consider an aluminum air tube since it will need a complete tear down. Haven't seen how much they cost in a long time, hole they are still for sale.
Probably a dumb question but I will ask anyway for the sake of safety. Is there anything internal in that valve that might shoot air into the transfer port somehow now it has failed? Pellet is still stuck in the barrel I don't want it going off into the wall next to where it is on the rack.
I will call crosman tomorrow.
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You can safely degas using the gauge. it seals via an o-ring at the bottom of the threaded hole, so if you back it out a bit it will slowly leak down. You don't need to worry about the gauge shooting out of the block as long as you keep the movement limited to a turn or so, and do be sure to move it around some as you do it - sometimes you get some flow and it stops before it is empty. I like to take the gauge all the way out once the pressure gets very low just to know it is fully empty.
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Okay, watching this video here https://www.youtube.com/watch?v=kCqPYmHG048 (https://www.youtube.com/watch?v=kCqPYmHG048)
I see how the valve works now. Sure looks like it was a dumb question about it possibly going off. Doing searches I found this thread on airgunnation and I suspect this is what happened to my poppet.
https://www.airgunnation.com/topic/marauder-rifle-poppet/ (https://www.airgunnation.com/topic/marauder-rifle-poppet/)
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If stock ... indeed somethings gone sideways IMO ....
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The problem as I see it is that if your poppet broke and looks like the one in the picture in the link, it would not hold pressure - the air would almost certainly leak out past the stem. And in the unlikely event it held pressure, it would not stay like that in that position if there was any pressure in the gun - the pressure would push the stem back against the remaining bit of seal that is pressed against the valve (the pressure would act on the 0.125" stem area, wish is atmospheric on the outside of the valve) and your stem would then protrude out the valve.
I don't see how that can be your problem if your gun has not dumped its air charge.
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I think that is the bottom of the stem with the bevel on it. I have heard of the poppet breaking and holding pressure, but it has not happened to me.
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Could the poppit stem have disintegrated leaving all the powdered metal, and now not long enough to open when the hammer drops?
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Ethan, we all look forward to you opening the valve and solving the mystery. :)
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Okay, ordered multiple parts, went ahead and ordered two valve stems as mobilehomer suggested, price was still 1.70 a piece. Also got a new valve spring just in case. And a bunch of other random o-rings just so I'll have them if needed down the road. Parts were all cheap. I didn't get a new valve body, that little dent shouldn't effect anything, but if it somehow does I'll order a new valve body. Parts are supposed to be here in 5-7 days so when I tear it back down I'll give an update.
Gun is still at the same pressure today, so it appears to still be completely air tight. Hunterwhite, the dust is just graphite powder for lubrication.
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I started wondering if I should have ordered a new valve body due to damage. I wanted to double check, so I tore it back down and cleaned the graphite powder to get a better look. Looks like the damage was just an illusion. There is no damage at all, picture attached. It's back together, now just waiting for a new valve stem.
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Speedy, just a word of caution. you have some high pressure on the other side of that stem. With not knowing what's going on or broken, that valve stem could become a projectile. Would be a good idea do degas it now and be done. Keep it pointed in a safe direction.
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I've had the same thing happen to me and it held pressure perfectly. The interference fit of the stem in the poppet head kept it sealer. As far as the stem shooting out, IMHO there isn't enough surface area to provide enough push to push it out.
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Either way you’re going to have to de-gas to make repairs. I kind of agree that it feels like an accident waiting to happen. My opinion is it’s best to just give it a slow pressure leak either at the gauge, or (I usually) bleed out slow through a connected pump.
As a bonus, you’ll be able to pull the valve ahead of the parts and show us what’s going on in or around it.
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It's back together so the hammer would block it's path anyway. Worst it could do is push on the hammer spring then make the air rush out. I want to keep it pressurized until the part comes to keep the o-rings fresh. No way it's blowing out the back of the tube, I just can't see that happening.
Cool to hear someone else had the exact failure. So was it like the picture in that link?
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I had this happen before, it was with one of my first home made poppets. When inserting the stem, I didn't bottom the stem out in the hole drilled in the poppet head. Initially I used it on a gun regulated at 1500psi, and it worked very well for quite some time, well over a year and thousands of shots. Later I moved it to a 3000psi unregulated application. The third shot resulted in a click---the stem moved in relation to the head........ I was rewarded with a 2800psi bomb, lol.... After quite a bit of inspection, head scratching, and a few choice words, I realized what had happened. In the end loosened the foster enough that it created a slow leak that fully degassed over night.
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As far as the stem shooting out, IMHO there isn't enough surface area to provide enough push to push it out.
The stem is 0.125", a pellet is 0.177".
I wouldn't spend too much time staring down into the tube.
Hunter
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Okay, it's done. Picture attached, old is on the bottom, new is on the top. It was exactly what was guessed. Glad I got a new spring too because look at the amount of rust on the old one. Gun always gets pumped indoors with air conditioning but I guess Ohio humidity can still be too much. I had to re-use an old o-ring because two got torn on the gauge port hole when re-assembling, not happy about that, whether it leaks or not will be known soon enough. I used a dremel and carefully de-burred the inside of the gauge port hole, after that the o-rings slid right over it, wish I had known to do that from the start. How the factory got them in there without the same thing happening is beyond me. I used a little Trident 100% silicone grease on the o-rings when assembling.
Now here's the mystery, I'm pretty sure the gun is shooting harder now, and I didn't change the tune. I did some quick night testing with a flashlight aimed at the target, and I thought it sounded louder (I didn't forget to put the de-pinger back in). The amount of shots brought the pressure down more than it should have. Very strange. If this is the case I will need to re-tune I guess. I'll get the chrony out with it tomorrow if the weather is good and I'm feeling it.
I have covid, right now, confirmed. Six days in of symptoms. Pumping the gun up from nothing to 3,000 was tough, and I needed to take more and longer breaks than I otherwise would have. Also went to show just how much air is crammed into that tube to get it to 3,000 psi, it's pretty neat.
EDIT
Come to think about it, the gauge port o-rings shouldn't matter much. So I hope the one on the valve is a new one. Cannot remember.
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YUP ... poppet stem driven right threw the poppet head !
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YUP ... poppet stem driven right threw the poppet head !
Yep. Maybe all the moisture rotted it? But I am really wondering if it had a small tear for a really long time because I'm pretty sure the gun is shooting harder now. Either that or the new valve spring is weaker, but I doubt that.
Also, I re-re-thought it over, the gauge port o-rings ARE important as to stop air from leaking out of the gauge port hole, duh. Hasn't leaked yet in hours, so it's a good sign so far.
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Cool....sheared the top part of the poppet off...nothing it could have done but end up with the valve stem shaft about even with the face of the valve.
Usually they'll slow leak down the exposed pin shaft when that happens.....and it does happen.
As much as we think of Delrin as non-reactive, it really isn't immune from hardening...and a right angle (like the "step" in the valve poppet from large to small) is a stress collector.
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I have hit those poppets with a heavy hammer tune as hard as any other power tuner has pushing a little over 75 FPE with my .25 Synrod. I have never had one to do me that way. So yes, that one may of had a flaw in it, or became overly hot while in the sunshine/heat.
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Thx for the follow up post. Lots of rust on that poppet stem, as well as the spring. How was the inside of the tube? Near the front gauge block o-ring is a typical problem area with high moisture conditions.
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Tube seemed mostly fine, not perfect. Nothing that's alarming me, just signs that eventually the tube will need replaced. I saw orange so rust wanted to start somewhere, likely where the depinger was sitting. After pushing some rags through everything looked really polished and shiny except for one very small spot, there was one really little smudge (smaller than a dime) that might have been early surface rust starting where the depinger was. I didn't see any rust rings where the o-rings were, there was a tiny bit of orange on the gauge port o-ring though, but I think that was just collected as it pushed past that smudge left by the depinger since it was not around the o-ring but in one small spot like was seen on the depinger. There was no pitting as far as a flashlight could tell me.
There was a lot of filth in the tube, picture attached. There is the depinger after coming out which collected a lot of the filth, that congealed clearish white stuff that looks like salt was soft to the touch and could be broken apart in your fingers. Maybe it's congealed silicone oil that gets in there when I'm pumping? I'm not sure what it was. And you can see a little orange on it too. All in all I think the tube is fine for now, if it needs replaced down the road it's easy enough to do. It would be an excuse to switch to an aluminum tube anyway, taking more than a pound off the gun.
By the way, as for it getting louder, I took a look at the dowel I used to measure how far to push the depinger, and it had another mark on it from a previous project from who knows when that I accidentally used. Took the fill valve off and sure enough the depinger was not pushed in far enough, it had like four inches to go. The factory pretty much had the depinger sitting directly in the middle of the tube so that's about what I did plus a little more to hopefully clear that smudge. I'm about to test the gun to with the chrony to check the tune. Hoping it didn't somehow change.
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tiggerheat:
Add the word "yet" and you're good.
Gauge blocks:
realize that they are open to the outside air between the two O-rings on the gauge block (through the tube hole for the gauge)….what happens there is unpressurized and not the fault of the fill air.
The inside of the valve (where that valve stem retrun spring lives) will see every bit of fill moisture pass though/collect on the spring...less moisture is going to take longer to rust it,but it will get rusted...it'swhere the drop in pressure/cooling/condensation would want to deposit it.
If you had not already put it all together, would tell you to "wax" (thin coat) everything inside with Silicone grease.
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tiggerheat:
Add the word "yet" and you're good.
Gauge blocks:
realize that they are open to the outside air between the two O-rings on the gauge block (through the tube hole for the gauge)….what happens there is unpressurized and not the fault of the fill air.
The inside of the valve (where that valve stem retrun spring lives) will see every bit of fill moisture pass though/collect on the spring...less moisture is going to take longer to rust it,but it will get rusted...it'swhere the drop in pressure/cooling/condensation would want to deposit it.
If you had not already put it all together, would tell you to "wax" (thin coat) everything inside with Silicone grease.
Using the gauge port with old o-rings I used the trident grease and pushed it through the tube a couple of times, adding grease each time. How well that will work I don't know. There is definitely a thin layer of grease though. The inside of the valve and valve stem just got a thin layer of silicone oil though. Valve is brass so it'll be fine. The spring and stem will inevitably rust again though.
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Glad it is fixed. I find two things amazing about that condition: 1) that the gun still held air like that at 2900 psi, and 2) that the stem was not pushed back down flush over time, as at 2900 psi there was about 35 pounds of pressure on that stem.
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To me, what I could tell, it got pushed flush over three shots. So it did hold for a little bit.
And puzzling but I do have a 40 fps increase. I am going to leave it for now, although I hope that the hardcast crosman pellets don't foul my barrel at 880-890 fps. I just got a couple sub .25" groups at 25 yards and some shot some earplugs at 50 so it can still shoot straight at this speed.
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Glad you are back in business!
I use a 3/4" wood dowel to work the HP tube. One end has a hole drilled in it to cover over the valve stem when installing/removing it. I put a rag or paper towel over the rod to clean out the tube. I lube the entire tube with silicon grease afterwards the same way, twisting as I go for more cleaning/lubing power. I have never seen any rust inside my two. I hand pumped for a couple of years with a Benji pump with no kind of filters, but did that indoors in drier air, and was mindful of heat buildup and didn't push it. I never trashed an O-ring in the hand pump either. I think the silicon lined reservoir had something to do with no rust inside, or I may have just been lucky. Either way, the inner components sure do slide in and out easily.