GTA
Airguns by Make and Model => Benjamin Airguns => Topic started by: sweatyk on May 11, 2025, 03:58:52 PM
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I need a little guidance. I'm just now starting to reassemble this rifle but I bought the seal kit approximately 12 years ago. I have the front end in with the new pump cup and pump handle reattached. I'm starting on the back end and there is a significant difference in the new check valve in comparison to the original. Being a newbie I don't think I can post pictures at this point but I'm looking for some advice. The new one is of course flat brass on one side and the black rubber side is completely flat also. The original has a center post with a black rubber seal around it. Would like to know before I start the assembly if I have the correct one. Same diameter but the new one is slightly thicker too. Has anyone had this before? If the pictures attach then the one on the left is the original.
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it will work, some rebuild kits come with a white disc of Delrin as the intake valve.
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Since posting this I did start the process and started installing things. I got the check valve in with the 2 springs and washers. When I got to the valve I had a hard time trying to get the threads to catch. Pulled it out and the lead ring was a bit boogered up. I dont think it's too bad and I might can straighten it up enough to work. I did read on another thread that someone said getting that in position is an art form.......I believe them. If it wont work is there a source for just single parts or would I have to purchase another kit to get one?
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I have reused the original lead seal on one I rebuilt, so I do have a spare plastic seal from a kit. I have also used a proper fitting oring and got a good seal also.
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My original is not in terrible shape and might get used if I can't get this one in good. I do have another question.....when I disassembled mine there were 2 washers between the springs where there is normally 1. With the new check valve being thicker than the original would it be ok to just use 1 washer between the springs? I don't know if that extra thickness would make it difficult to get the nut started.
Forgive me for the dumb questions. This is my first rebuild of an airgun, however I tear down everything to repair it.....I just have a curious nature
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One other question. What type of grease is safe to use to help hold the rubber and lead o-rings in place on he valve while trying to install?
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One other question. What type of grease is safe to use to help hold the rubber and lead o-rings in place on he valve while trying to install?
Would dielectric grease work for this application?
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My original is not in terrible shape and might get used if I can't get this one in good. I do have another question.....when I disassembled mine there were 2 washers between the springs where there is normally 1. With the new check valve being thicker than the original would it be ok to just use 1 washer between the springs? I don't know if that extra thickness would make it difficult to get the nut started.
Forgive me for the dumb questions. This is my first rebuild of an airgun, however I tear down everything to repair it.....I just have a curious nature
According to UJ's repair manual some guns do have two washers between the springs. When I rebuilt my Sheridan per that manual it shows to start the nut place the tool and nut in the tube action and hold the tube vertical while pressing down on the work bench and slowly rotate the tube action itself until the threads catch. This helps overcome the valve intake spring resistance. I ditched the lead seals and used Teflon washers instead. They hold air indefinitely where the lead did not in my gun.
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The theory is that petroleum based grease or oil will degrade the seals over time, and if in the compression chamber, may ignite due to dieseling. I've never actually seen a problem with any of that, but to be safe, still use silicone based grease, like divers grease or o-ring grease. And you can install the nut without any of the other guts, and put a mark (sharpie or whatever) on the tool when you hit the threads. That way you'll know visually when the nut, with all the internals in place, is ready to thread doing as Van suggested.
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Thanks guys. I have tried a few times today and still not able to get it catch the thread. I removed the second washer and put the original spring back in but still having a difficult time. I will continue forward until I get this...........
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Forgive the bad picture but something that I overlooked is the surface that meets the rubber gasket. At a glance it appeared to be clean when I started this but closer inspection shows some of the old gasket bonded to the surface. This may or may not be whats keeping me from getting the nut started but it needs to come off. I've tried some 91% alcohol on a gun patch and trying to scrape it off using a chopstick. What do you guys use to get in there and clean that surface without causing any damage. Open to suggestions.
Picture is crappy but you might be able to see what I'm referring to.
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Thanks guys. I have tried a few times today and still not able to get it catch the thread. I removed the second washer and put the original spring back in but still having a difficult time. I will continue forward until I get this...........
I had a problem getting that nut started on a Benjamin 310 with lead seals which is similar valve. I made a seal from Teflon valve rope packing from the plumbing section a Lowes. It compressed more than the lead and forming to the seat to give me enough slack to start the nut in the threads. It has been holding for many years now. Another member here who could not get the nut to start used this stuff to seal a Dan and reported that it worked on the first try.
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Forgive the bad picture but something that I overlooked is the surface that meets the rubber gasket. At a glance it appeared to be clean when I started this but closer inspection shows some of the old gasket bonded to the surface. This may or may not be whats keeping me from getting the nut started but it needs to come off. I've tried some 91% alcohol on a gun patch and trying to scrape it off using a chopstick. What do you guys use to get in there and clean that surface without causing any damage. Open to suggestions.
Picture is crappy but you might be able to see what I'm referring to.
I used a brass rod to prevent damage that I sharpened to make a flat scraper and Goo Gone to remove that old residue then a wood dowel with a fine piece of sandpaper glued to the tip to gently smooth up after. It was tough to get off but worked out ok. After all the work flush and flush again with 90% alcohol till all the tube comes clean.
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I was thinking about using a valve lapping tool with something on the end to get it off. I played *(&^ getting it off of the valve. Had to use a small flathead and cautiously scrape little by little
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I think I would try a pad of green Scotch Brite cut round and glued to the end a wood dowel soaked with Goo Gone if I had to do it again. That would not damage the metal seat but goo gone might keep the pad from sticking to the dowel.
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I think I would try a pad of green Scotch Brite cut round and glued to the end a wood dowel soaked with Goo Gone if I had to do it again. That would not damage the metal seat but goo gone might keep the pad from sticking to the dowel.
I bought a valve lapping tool to use. I'll bond the scotch brite pad to it so that it does not come off. But before I start this major cleaning process I'm going to remove the pump section on the front that I have already installed to ensure no trash gets in there. I hate to have to remove it but it is the right thing to do.
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I don't usually promote my own videos, but the first few minutes of this one might help;
https://youtu.be/c4_A3Cg6i8o?feature=shared
The brass rod is a good suggestion, unless you run into a particularly stubborn one.
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Jon I had no idea this was you. I've been watching your videos on the streak from "heck" for years now. It is what inspired me to do the rebuild myself. Thank you for your contributions!
I'll check out this video.
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That valve body seal can be lead or rubber. Mine was rubber with a lead seal under the nut. Some guns had two lead seals with no rubber one. I think you have a deteriorated rubber one back there like I did. Also if you have the eairler valve body with a single exhaust port the tab must be lined up with the slot in the chamber when you install it.
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That valve body seal can be lead or rubber. Mine was rubber with a lead seal under the nut. Some guns had two lead seals with no rubber one. I think you have a deteriorated rubber one back there like I did.
Yes it was rubber.....and it had fused to both the valve and the facing in the chamber. It took a good bit of effort to get it off the valve. Got some ideas to get it off the other end. Once done I'll go through and make sure there's no debris left and start the reassembly again
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I just added to my post above about the single exhaust port valve vs the multiport one. Which do you have? The single port must be in the right way or you cant start the nut without breaking off the tab and the port will not be lined up. The multi can go in any way.
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I just added to my post above about the single exhaust port valve vs the multiport one. Which do you have? The single port must be in the right way or you cant start the nut without breaking off the tab and the port will not be lined up. The multi can go in any way.
Mine is the multi port. 4 openings on it
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I managed to get the fused rubber gasket material off of the mating surface inside. It turned out really good. As for installing the valve, I'm still not able to get the threads started on the nut. No matter how hard I push down it doesn't seem far enough. The one thing that I haven't done is to compress the new exhaust spring. I did try to do it with the original spring thinking it would be easier but it was no different. I'm done for this evening so I will try again tomorrow.
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If you are using two new lead seals they can be hard to compress enough to start the nut. Try leaving out the lead seal under the nut. If the nut starts then crank it down to see if it will compress the valve seal enough to make it start then add the second seal under the nut. I had to use the TEF rope I mentioned above under the nut on one gun when i could not get the lead one to compress enough to start the nut when using both lead seals. It is easier to compress than lead. If Mac1 is still working on getting back open he has thiner flat white TEF seals for those locations that work so much better than lead for me. I used them on two other guns and the nuts started so easy.
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If you are using two new lead seals they can be hard to compress enough to start the nut. Try leaving out the lead seal under the nut. If the nut starts then crank it down to see if it will compress the valve seal enough to make it start then add the second seal under the nut. I had to use the TEF rope I mentioned above under the nut on one gun when i could not get the lead one to compress enough to start the nut when using both lead seals. It is easier to compress than lead. If Mac1 is still working on getting back open he has thiner flat white TEF seals for those locations that work so much better than lead for me. I used them on two other guns and the nuts started so easy.
Only the rear washer is lead. The front that mates to the inside surface is a flat rubber ring. I was pondering if perhaps the tip of the exhaust valve is not fully seating into the opening of the spring. That would certainly be enough space to keep the threads from starting on the nut. I wonder if that has ever happened to anyone before?
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I removed all of the springs and put the valve in with no gaskets on it, i was able to catch a thread.....good so far. So then I put the rubber gasket (o-ring) on the front and installed it....again I was able to start the nut in the threads. Put the new lead gasket on the rear and could not get it to catch a thread. I swapped the new lead gasket for the original and it still wont catch a thread. >:(
Guys I have no spring tension to deal with and it still wont get started......There should be nothing to keep it from catching. What am I missing?
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If you are using two new lead seals they can be hard to compress enough to start the nut. Try leaving out the lead seal under the nut. If the nut starts then crank it down to see if it will compress the valve seal enough to make it start then add the second seal under the nut. I had to use the TEF rope I mentioned above under the nut on one gun when i could not get the lead one to compress enough to start the nut when using both lead seals. It is easier to compress than lead. If Mac1 is still working on getting back open he has thiner flat white TEF seals for those locations that work so much better than lead for me. I used them on two other guns and the nuts started so easy.
Only the rear washer is lead. The front that mates to the inside surface is a flat rubber ring. I was pondering if perhaps the tip of the exhaust valve is not fully seating into the opening of the spring. That would certainly be enough space to keep the threads from starting on the nut. I wonder if that has ever happened to anyone before?
If your gun is an older one It used an exhaust valve with a 5/32'' diameter raised boss that seats into a spring of that size opening. The later "C" guns used a 1/4" boss and fit in a spring with a larger spring opening. A later valve would not seat into an early spring if mismatched. Thats the only thing I can think of to keep it from fully seating.
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If you are using two new lead seals they can be hard to compress enough to start the nut. Try leaving out the lead seal under the nut. If the nut starts then crank it down to see if it will compress the valve seal enough to make it start then add the second seal under the nut. I had to use the TEF rope I mentioned above under the nut on one gun when i could not get the lead one to compress enough to start the nut when using both lead seals. It is easier to compress than lead. If Mac1 is still working on getting back open he has thiner flat white TEF seals for those locations that work so much better than lead for me. I used them on two other guns and the nuts started so easy.
Only the rear washer is lead. The front that mates to the inside surface is a flat rubber ring. I was pondering if perhaps the tip of the exhaust valve is not fully seating into the opening of the spring. That would certainly be enough space to keep the threads from starting on the nut. I wonder if that has ever happened to anyone before?
If your gun is an older one It used an exhaust valve with a 5/32'' diameter raised boss that seats into a spring of that size opening. The later "C" guns used a 1/4" boss and fit in a spring with a larger spring opening. A later valve would not seat into an early spring if mismatched. Thats the only thing I can think of to keep it from fully seating.
But I removed the springs from the equation and just used the valve itself to test fit. That's what has me puzzled. And the fact that it's the original valve with the original lead o-ring between the valve and the nut. The only thing new to the equation is the rubber o-ring which is quite thin and I can't see it stopping this from getting started even without the springs installed.
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Here is a photo of the assembly page from the repair manual stating to leave out the lead seal under the nut with everything else in place including the seal under the valve and only use that seal under the nut if you get blowback when fired. If the nut tightens down and no blowback you may not have to have that seal. One of the seals may be too thick for the nut to catch.
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Here is a photo of the assembly page from the repair manual stating to leave out the lead seal under the nut with everything else in place including the seal under the valve and only use that seal under the nut if you get blowback when fired. If the nut tightens down and no blowback you may not have to have that seal. One of the seals may be too thick for the nut to catch.
Before reading your post I also had this thought....leaving the lead washer off (as you pointed out) but put a little teflon tape on the threads of the nut to help seal it?
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So I have left the lead o-ring off and was able to get the nut to catch and tightened it. I pumped it a few times and tapped the firing pin and got it to fire. I pumped it 8 times and when it fired I felt some blowback coming out of the end. It might have been coming from where the bolt sits but I'm not sure. Would that be expected? I didn't put any teflon tape on the threads but if needed I can do that.......Thoughts?
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OK....8 pumps and now we wait to see if there is any leakage....... 8)
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Great news! After sitting overnight holding 8 pumps, there was no leakage from the check valve or the rear of the exhaust valve. Time to start the rest of the reassembly. Thanks to everyone for your assistance and guidance. I will continue to post the progress until she's completed.
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Great! Lead seals are hard to get compressed enough in my experience. That seal under the nut is only necessary according to the manual if it has blowback without it. Always glad to see a classic like that restored because they truly don't make them like that anymore. At 8 pumps my 1971 model is shooting 685fps with the old Sheridan 14.3g pellets and around 700fps with 13.73g JSB Exact. I got that by adding an adjustable pump rod to get more air in per pump. If the bolt O ring leaks it can be replaced with a size 004 Buna. If there is too much blowback, with a good bolt seal, try the tape or the Tef Valve Packing Rope under the nut. That worked for me on one gun that had a problem getting that nut to start. JSB Exacts are the best of the modern pellets, I think. Let us know how she shoots.
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Will do. I bought mine new in 1977 I think. How is the serial number interpreted for the date of manufacturing? Mine is 178635
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JG Airgun has a list of Sheridan serial numbers that I have printed. 1977 went from 175840-211020 so it falls in that year.
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JG Airgun has a list of Sheridan serial numbers that I have printed. 1977 went from 175840-211020 so it falls in that year.
I mowed a lot of lawns back then to buy it......
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Everything is back together with the exception of the trigger guard which I seemed to have misplaced. It will turn up eventually. Ran a pellet through it and it fired just as it did the day I bought it. All I have left to do other than find the trigger guard is apply a finish to the sanded stock. It looked horrible when I first took it apart so I sanded all of the finish off. I have a bottle of Tru-oil from Birchwood that I plan to use on it. I'm very happy with the results once I got past the valve issue. Thanks again for those who chimed in and shared your experience and knowledge.
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(https://www.gatewaytoairguns.org/GTA/Themes/CustomGTA2023/images/post/thumbup.gif)
Glad to see another classic back in action ;D 8)
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I found the trigger guard now I need to find the time to refinish the stock 😝