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Thread: Oil out of cam breather

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    Default Oil out of cam breather

    Well I fired up my new built C16SE tonight I’m running twin 40s.
    Started up after 5 turns beautifully,went for a drive 7 miles in starts missing/smoking out of exhaust and oil out of the cam cover breather,removed all 4 plugs to find number 4 oily,I’m thinking blow by what are your thoughts?? Can’t find my compression tester,what compression should I be looking for roughly? Can’t see it been a hole in piston from running lean.
    It was smooth,no smoke and no nasty noises just suddenly smoke then missing

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    maybe the rings died

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    Default Oil out of cam breather

    My 20XE did this, number 1 oil control ring was screwed.

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    First step would be compression test check all and that will give you a good idea of what 4 should be if it comes back low. If its not a ring then I'd maybe be looking for a stem seal that isn't seated properly after the rebuild

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    Quote Originally Posted by millworm View Post
    First step would be compression test check all and that will give you a good idea of what 4 should be if it comes back low. If its not a ring then I'd maybe be looking for a stem seal that isn't seated properly after the rebuild
    Stem seal wouldn't start pressurising the crank and forcing oil out the breather though.

    Could be a piston ring, or maybe headgasket? Compression and leakdown test will help but sounds like the heads coming off as a minimum to investigate.

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    I’m on holiday so once back I will be testing compression,I’m wondering if one of or all the other rings are losing compression because if oil is forced past cylinder 4 piston compression must be getting into crank from one of other piston or pistons to be pressuring the bottom end,really can’t see head gasket failing

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    Rite landed back in the uk so pressed on with this,used my cheap compression tester and numbers 1 2 and 3 were only at 75psi which is half what I expected.number 4 had 0 psi.
    iv removed the head and found on the inlet side of piston melted.
    what are your thoughts??
    im going to pull all the pistons to check rings and timing of rings.
    i think iv had my ignition to retarded,which caused the hole in piston

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    I did do the compression test cold for obvious reasons,compression test carried out without throttle open

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    Just got off the phone with David bogg he says it sounds like a faulty piston

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    Were the pistons new? If its melted, its more likely to be down to ignition/fuelling and it running extremely lean on that cylinder.

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