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I recently found engine oil in all four exhaust pipes. Engine has only ran for 10th hrs. I'm using 100 ll with aeroshell engine oil. I did the compression check on all four cylinders and the pressure cane out to 9 bars. I didn't exceed any CHT, EGT oil pressure limits during this 10 hours.I removed the exhaust pipe on one the cylinder to take better look and it seems like its leaking from exhaust valve guide. Not sure. Please help.
  • Re: Rotax 912S Oil in exhaust pipe need help urgent

    by » 11 years ago


    Hi Asad

    Your problem is interesting and no doubt will take some trouble shooting, sounds like you need a qualified tech to help you out.

    You can search for the nearest iRMT using the "Find Support" section of this Rotax-Owner web site!

    You mentioned you are using Aeroshell Engine oil but not what type exactly, is it the Aeroshell Sport Plus 4 designed for a Rotax or the regular Aeroshell Aircraft oil for Lycomings and Continental engines?

    Has the engine been burning excess oil?

    Does it blow blue smoke out of the exhaust especially on start up?

    Is the oil tank vent line blocked? If it is, the crank case pressure of the engine will rise beyond limits forcing oil out seals, gaskets, o-rings and yes even past the valve guides!

  • Re: Rotax 912S Oil in exhaust pipe need help urgent

    by » 11 years ago


    Thanks a lot for your reply. I am using sports 4 . This problem is more evident at lower rpm between 1600 to 3500.is crank pressure higher at lower rpms.will check the crank pressure first thing on Monday. Thanks a lot.

  • Re: Rotax 912S Oil in exhaust pipe need help urgent

    by » 11 years ago


    I didn't notice any blue smoke. Will look it to that.

  • Re: Rotax 912S Oil in exhaust pipe need help urgent

    by » 11 years ago


    What type of plane is this? Oil in the exhaust is quite common in aircraft that has an installation where the oil tank is mounted higher than the centerline of the engine,ie Searey or Aventura.The oil siphons back into the engine and fills the crankcase.It then seeps past the piston/rings and then the combustion chamber.Depending on which valve is open,the oil will reside in the intake or exhaust.Engine will run fine once the oil has been purged from the cylenders effected.Older Kitfox had the same problem.Usually occurs when the plane has sat for two or more weeks...Hope this helps..

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