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Cylinder 4(?) exhaust knuckle leaking

in 912 / 914 Technical Questions 7 years ago
Hi guys,

Wondering if you could advise as to if this is a common issue / any history? Getting a poor connection on the exhaust knuckle from rearmost right hand cylinder which I assume is numbered 4. This is leading to gases leaking when the engine is hot.

Cheers
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File_000.jpeg (You do not have access to download this file.)

  • Re: Cylinder 4(?) exhaust knuckle leaking

    by » 7 years ago

    Typically 1& 3 on the right and 2&4 on the left on a tractor prop setup.
    Leakage at this point and this much is not normal or common.
    I would disassemble this and see what's going on inside. It maybe cracked or the metal eaten away from vibration and exhaust impulses. It needs further investigation.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: Cylinder 4(?) exhaust knuckle leaking

    by » 7 years ago

    I noticed that the OP is apparently using "springs" on his exhaust studs -- is this common? Perhaps this is why he is seeing some exhaust gas leakage?? The 912 in my RV-12 uses the more direct nut / flange / stud attachment arrangement.
      
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  • Re: Cylinder 4(?) exhaust knuckle leaking

    by » 7 years ago

    Also the flat metal plate that is supposed to hold the exhaust tube in place seems to be different to what I know as"original". Usuallly, we see more like a shaped cover to hold everything together. Unfortunately I have no picture at hand, but if you get one you'll know what I mean.
      
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  • Re: Cylinder 4(?) exhaust knuckle leaking

    by » 7 years ago

    No matter what the mount it needs to come apart for a look.
    Do you know what the nut torque is with that spring setup? The spring setup looks like some aftermarket setup? Are you the original owner? If not someone may have made this installation.
    You can opt to return this back to an original exhaust mount.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report
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