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N/A Crosman 157 resealed leaks Pls Help

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vintageairguncollector@gm

vintageairguncollector@gm

Member
Dec 26, 2023
103
112
Happy, State of Mind, USA
Bought Baker airgun kit and installed it. Gun shoots about 30 shots but then I can hear the gas leaking out the barrel. Slowly and quietly the gas leaks out the barrel.

Could someone with experience help me? What did I do wrong to make the slow leak? The airgun was broke when I bought it on ebay and I am a newbie just trying to learn about airguns.

Randy
 
Randy,
No expert, re-sealed mine Jan. 2021 using $5.50 seal kit from Mlandon61 (eBay), following Eagle View HD's YouTube video, from 4 years ago, called, "Crosman 150 or Crosman 157 Disassembly," found challenging, but doable. Hard to say where your problem lies, hopefully gun isn't damaged more than a re-seal will fix. In your shoes, I'd get another seal kit and follow video to re-seal, paying close attention for internal damage. Use heavy-weight silicone oil liberally on seals and scrutinize carefully burrs or sharp edges which might cut seals. WM
IMG_20221030_141252.jpg
 
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CtShooter

Thanks for the advice and direction. Since I have slow leak that stops when a pellet goes into the chamber. I beleive the valve stem is been slightly depressed by the hammer prior discharge. Also I not sure which o-ring went where, so I think I have to change o-rings around. Please remember me if you are sell vintage spring air pistols.

WorriedMan
I agree this your postion that we learn more as we practice airgun-smithing. I think I can fix it by changing the valve body o ring. I think it leaking from the back of the Co2 holding tube. Just an educated guess about the leak location. I am enjoy learning each time I rebuild it I am smoother at the process.
Thank you for your help.
 
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vintageairguncollector@gm said:
CtShooter

Thanks for the advice and direction. Since I have slow leak that stops when a pellet goes into the chamber. I beleive the valve stem is been slightly depressed by the hammer prior discharge. Also I not sure which o-ring went where, so I think I have to change o-rings around. Please remember me if you are sell vintage spring air pistols.

WorriedMan
I agree this your postion that we learn more as we practice airgun-smithing. I think I can fix it by changing the valve body o ring. I think it leaking from the back of the Co2 holding tube. Just an educated guess about the leak location. I am enjoy learning each time I rebuild it I am smoother at the process.
Thank you for your help.
Click to expand...
Certainly, agree we learn by doing. If my 2021 reseal efforts were unsatisfactory to me, I'd have gone back in and searched out why, after reviewing the instructional video. (Had to do same thing rebuilding my Chinese HPA handpump.) Anybody can miss anything, no matter how much care is exercised. Suggested a path forward for you based upon what I'd have done, adding tips on parts and helpful videos. Wishing you the best of luck, WM
 
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Your leak through the barrel probably means the exhaust/firing-valve is leaking at its (hard synthetic) seal. Even new ones will sometimes leak.

Such a slow leak can usually be corrected by removing the whole valve mechanism, including the valve body and firing valve (stem). Locate the valve seating surfaces, and use a fine polishing compound on those surfaces as you spin the chucked-up valve stem while applying enough pressure to polish the valve-seal against the valve-stem seating surface on the valve body.

.
 
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Replacing the valve spring and pin with plunger fixed the problem. The valve was remaining open after a few shots or even just one pellet with all the gas exiting out the barrel. I believe replacing the spring in the valve fixed it. The old spring felt weak the new one felt too siff but it was perfect.

Lesson Learned - When in doubt- springs come out. I can t measure spring tension with my fingers duh!

Shoots great, so I am really happy with my 157; I used up a bunch of co2 s figuring out the problem. Also bought a seal kit too. I shot my 150 often and recently added a scope and a trigger job. Planning on adding a rail for Red Dot and a laser to the 157.

Thank you for suggestions and encouragement along the way.

Rand
 
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