Author Topic: Valve pin on Marauder is stuck flush with valve body but no leak? (Read 1156 times))

SpeedyBB · « **on:** August 31, 2020, 07:42:41 PM »

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.

SpeedyBB · « **Reply #1 on:** August 31, 2020, 07:54:16 PM »

Here is the picture. Same picture but I added a second which is zoomed in. Doesn't look broken to me.

FuzzyGrub · « **Reply #2 on:** August 31, 2020, 07:58:32 PM »

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.

Motorhead · « **Reply #3 on:** August 31, 2020, 08:43:23 PM »

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

mobilehomer · « **Reply #4 on:** August 31, 2020, 08:46:35 PM »

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.

SpeedyBB · « **Reply #5 on:** August 31, 2020, 09:20:01 PM »

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.

AlanMcD · « **Reply #6 on:** August 31, 2020, 09:42:44 PM »

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.

SpeedyBB · « **Reply #7 on:** August 31, 2020, 10:44:54 PM »

Okay, watching this video here

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/

Motorhead · « **Reply #8 on:** August 31, 2020, 10:59:48 PM »

If stock ... indeed somethings gone sideways IMO ....

AlanMcD · « **Reply #9 on:** September 01, 2020, 06:50:44 AM »

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.

FuzzyGrub · « **Reply #10 on:** September 01, 2020, 09:48:33 AM »

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.

HunterWhite · « **Reply #11 on:** September 01, 2020, 12:55:46 PM »

Could the poppit stem have disintegrated leaving all the powdered metal, and now not long enough to open when the hammer drops?

FuzzyGrub · « **Reply #12 on:** September 01, 2020, 12:59:56 PM »

Ethan, we all look forward to you opening the valve and solving the mystery.

SpeedyBB · « **Reply #13 on:** September 01, 2020, 04:43:45 PM »

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.

SpeedyBB · « **Reply #14 on:** September 01, 2020, 05:19:01 PM »

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.

RDB · « **Reply #15 on:** September 01, 2020, 05:42:44 PM »

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.

Madd Hatter · « **Reply #16 on:** September 01, 2020, 07:51:44 PM »

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.

Blue · « **Reply #17 on:** September 01, 2020, 08:24:57 PM »

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.

SpeedyBB · « **Reply #18 on:** September 01, 2020, 08:31:16 PM »

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?

mackeral5 · « **Reply #19 on:** September 01, 2020, 08:42:07 PM »

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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Valve pin on Marauder is stuck flush with valve body but no leak?

Author Topic: Valve pin on Marauder is stuck flush with valve body but no leak? (Read 1156 times))