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New 912ULS cylinder head

in 912 / 914 Technical Questions 7 years ago
Hi there. Is it necessary to purge the oil system of air when fitting a replacement cylinder head on a 912ULS? I know the oil purge must take place when the suction side from oil tank to pump has been opened but not sure about for replacing a head. Is it sufficient to turn the engine over by hand (without plugs) to cycle oil through the new head and ensure that oil pressure is seen to rise? Thanks

  • Re: New 912ULS cylinder head

    by » 7 years ago

    The new oil purge service instruction SI-912-018 Rev 2 (just released) sec 1.5 NOTE mentions that you do not have to purge unless the oil pressure galleries have been drained or you replace the oil cooler (introducing a large amount of air into the pressure system).
    Component replacement that does not drain the galleries (specifically the lifters) do not require a purge.
      
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  • Re: New 912ULS cylinder head

    by » 7 years ago

    Hi Rob,
    What about an oil purge after a oil hose change? Cooler stays full.

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

      
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  • Re: New 912ULS cylinder head

    by » 7 years ago

    as long as you make sure the oil pressure galleries are not drained.
      
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  • Re: New 912ULS cylinder head

    by » 7 years ago

    Thank you Roger and Rob for your replies.

    Rob please can I ask what specifically you mean by the oil pressure galleries? It was my understanding that if the oil lines are opened on the suction side (ie. from the oil tank to the oil pump, which includes the oil cooler) a significant amount of air can be introduced to the system and therefore it must be purged. Changing oil hoses after the oil pump, or the oil filter (on the positive pressure side) is ok provided the prop is not turned through. If I have removed a cylinder head are you saying that provided the hydraulic lifters are NOT removed from the crankcase no purging is required but if the lifters ARE removed (and therefore drained of oil) purging IS required?

    I have not removed the lifters. I have re-fitted the new cylinder head and turned the prop through with the top spark plugs removed to cycle the oil through the new head and ensure that rising oil pressure is indicated. Is this ok?

    Many thanks
      
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  • Re: New 912ULS cylinder head

    by » 7 years ago

    With the cylinder head removed and the engine sat for a period of time will the lifters drain of oil even if they are not removed from the engine and therefore require purging? The engine has been sat without its head for about three weeks while we waited for a new head to arrive.
      
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