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Thread: S400 Breech seal still leaks

  1. #16
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    S400 .177 breech seal part no s536-bs008
    S400 .22 breech seal part no s538-bs009
    Transfer port seal part no s427- 6x1
    take the bs number and the 6x1 into a bearing/ seal supplier and you should be able to get them off the shelf.

  2. #17
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    Quote Originally Posted by Gwylan View Post
    I've lost count of the number of shots I've put through my S400s. If you have to replace them every 2 tins, there's something wrong. OP, are you sure it's the breech seal? The transfer port Oring seal can leak from around the same area, and it's easily misplaced, or even lost, when you do a rebuild.

    Gus
    I agree with Gus. You have to be very careful it doesn't move out of position during the rebuild.
    Try placing a paper tissue over suspect area then dry-fire and watch the tissue for movement.

  3. #18
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    Quote Originally Posted by Simonsays View Post
    Thank you but er which collet and seal please?
    'Brass barrel shim' & 'o-ring 58' on chambers diagrams.

    My brother somehow put them in the wrong way round, which gave 9ftlb with loads of blowback.

    As mentioned, this will probably be obvious to hardened 's series' tinkerers.

  4. #19
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    At one time I think it was UKNeil who made some seals for the transfer port area, using an O ring and a brass ring to stop the seal being drawn through and fired out. Also makes them much easier to place, and to keep in place.
    www.shebbearshooters.co.uk. Ask for Rich and try the coffee

  5. #20
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    Sep 2011
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    Quote Originally Posted by Gwylan View Post
    I've lost count of the number of shots I've put through my S400s. If you have to replace them every 2 tins, there's something wrong. OP, are you sure it's the breech seal? The transfer port Oring seal can leak from around the same area, and it's easily misplaced, or even lost, when you do a rebuild.

    Gus
    I replaced TP with a new seal as well. Incidentally, there is a brass washer that I assume sits inside the TP seal. Can't locate this on the parts diagram so would appreciate confirmation.

    Pretty sure TP seal went back as it should. Leak is coming from the breach, I feel the puff of air on my face when shoting. But I take note of your suggestion.

    It'll get another strip shortly so I'll check it out. Thanks

    S

  6. #21
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    Sep 2011
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    Quote Originally Posted by p.sharp View Post
    'Brass barrel shim' & 'o-ring 58' on chambers diagrams.

    My brother somehow put them in the wrong way round, which gave 9ftlb with loads of blowback.

    As mentioned, this will probably be obvious to hardened 's series' tinkerers.
    Noted thank you.

  7. #22
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    Sep 2011
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    Quote Originally Posted by Rich View Post
    At one time I think it was UKNeil who made some seals for the transfer port area, using an O ring and a brass ring to stop the seal being drawn through and fired out. Also makes them much easier to place, and to keep in place.
    Ah, got one of those! Another mystery solved! Cheers. S

  8. #23
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    Sep 2011
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    Quote Originally Posted by robsue20 View Post
    S400 .177 breech seal part no s536-bs008
    S400 .22 breech seal part no s538-bs009
    Transfer port seal part no s427- 6x1
    take the bs number and the 6x1 into a bearing/ seal supplier and you should be able to get them off the shelf.
    Excellent. Thanks for the info.

  9. #24
    Join Date
    Oct 2004
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    Nuneaton, Warwickshire
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    Quote Originally Posted by Rich View Post
    At one time I think it was UKNeil who made some seals for the transfer port area, using an O ring and a brass ring to stop the seal being drawn through and fired out. Also makes them much easier to place, and to keep in place.
    It was me mate, I did hundreds of those for people with the problem of the S400 series eating the transfer port 'O' ring........ It's almost a reverse Dowty seal.


    Neil
    Current airguns:- Steyr LG110: Steyr LP10: Air Arms HFT500: Weihrauch97 fully customised.

  10. #25
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    Sep 2011
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    Leak update

    I have had a good look at this and found that:

    1. The leak is largely between the brass breech block and the probe housing in which the breech block is located. The leak therefore independent of the probe tip o ring.

    2. The breech block hole and transfer port are not as well aligned as they might be which probably doesn't help. I replaced TP o ring and refitted With the UK Neil washer.

    3. The brass breech block is in tight (i assume glued) and hairdryer heat not enough to loosen it.

    How much heat can I apply (with a gun) without harming the probe housing finishing. Is the finish blued? If so then it won't be so fragile.

    I am itching to remove and reseal this but am stuck at the first hurdle. Any hint and tips please?

    To those following my earlier threads, sweet spot fully sorted by replacing hammer spring and firing valve. Thanks for all the help on this, much appreciated.

  11. #26
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    Jul 2003
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    what bolt do you have? the aluminium was too loose. hence some of the answers.
    got it. dead simple. no fuss. a reread just reminded me. the cap nut on the bolt is loose.
    put some locktite on it. no more spending out on seals that are not wrong.
    the only thing i can find wrong is the nut on the steering wheel.

  12. #27
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    Sep 2004
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    Not sure about your paragraph 1/, if it's leaking around the brass insert, it can't be glued in properly. A hot air gun should shift it. You can use too much Loctite when you replace it, and glue the whole thing into the breech block. Are there dints in the top of the barrel were the grub screws fit? you can usually rotate the whole barrel to line the two holes up.

    Gus
    The ox is slow, but the earth is patient.

  13. #28
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    Sep 2011
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    Quote Originally Posted by max headroom View Post
    what bolt do you have? the aluminium was too loose. hence some of the answers.
    got it. dead simple. no fuss. a reread just reminded me. the cap nut on the bolt is loose.
    put some locktite on it. no more spending out on seals that are not wrong.
    Thanks, its not from the probe seal however but blowing down the side of the brass breech. Confirmed this with soapy water.
    Nevertheless there'll be some benefit in checking the bolt etc. It seems to be aluminium. The attaching Allen bolt is tight and doesn't work loose. The o ring on the bolt allows firm lock up but appears thicker than standard which won't help. However its the breech blow by I cannot access to resolve.
    S

  14. #29
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    Quote Originally Posted by Gwylan View Post
    Not sure about your paragraph 1/, if it's leaking around the brass insert, it can't be glued in properly. A hot air gun should shift it. You can use too much Loctite when you replace it, and glue the whole thing into the breech block. Are there dints in the top of the barrel were the grub screws fit? you can usually rotate the whole barrel to line the two holes up.

    Gus
    As you conclude it ain't glued in correctly. If i can get the brass block out I can sort it. Suspect the answer is indeed a heat gun but had a reservation about cooking the finish so was looking for some reassurance on that before diving in.

  15. #30
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    Sep 2011
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    Quote Originally Posted by Gwylan View Post
    Not sure about your paragraph 1/, if it's leaking around the brass insert, it can't be glued in properly. A hot air gun should shift it. You can use too much Loctite when you replace it, and glue the whole thing into the breech block. Are there dints in the top of the barrel were the grub screws fit? you can usually rotate the whole barrel to line the two holes up.

    Gus
    Yes there are locating dints. Thanks Gus.

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