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I have been experiencing coking problems in my 914. This is a serious issue as the deposits will block the turbo oil return line causing oil to exit the turbo bearing out the exhaust draining oil and causing lots of smoke.

I am using the Rotax Oil in the crankcase, change oil and filter every 25 hours, do run 100LL as that is all thats available at airports I fly through. I also remove and clean the oil sump can and screen every 2-3 oil changes.

Since the last event I have richened the carbs one more notch to the richest setting. Hopefully this will help. I do not have a EGT or TIT gauge, the sensors just go directly into the computer.

Some have suggested using TCP fuel additive to help.

Others experience?
  • Re: 914 turbo coking

    by » 13 years ago


    Hi peter,

    Coking may be coming from a tiny oil seep or running too cool. Are your temps up where they are supposed to be?

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


    Thank you said by: Capt. Siva,

  • Re: 914 turbo coking

    by » 13 years ago


    make sure your using a semi-synthetic oil when running 100ll. clean the oil can every time to get that lead out it will build in your engine. also let turbo cool before shut down. what are your temps like?

  • Re: 914 turbo coking

    by » 13 years ago


    Troy is right. All of us should be using a semi or full synthetic oil and not straight mineral oils. Your engine will still love you at a 1000 or 2000 hrs from now. :)

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


  • Re: 914 turbo coking

    by » 13 years ago


    I am using the Shell oil specifically formulated for Rotax 912/914 engines http://www.shell.com/home/content/aviation/products/lubricants/piston_engine_oils/sports_plus4/ this is suposed to be the latest and best for the 912/914 series of engines.

    All my research indicated that turbo coking comes from exxcive oil temps in the turbo bearing. I do let the engine idle a minimum of 60 seconds usually much more until temps down. Typically cylinder head temps run around 120C and oil temps on the low end especially in colder weather. Plane does not have EGT or TIT gauges from factory.

  • Re: 914 turbo coking

    by » 13 years ago


    I have a 914 in my sabre. Clocked up 900 hours. Had some problems with fuel pressures in the carbys, the turbo, although complicated enough, has worked ok,Found that the engine runs very cold on a big descent, so we fitted a in line themostat, which could help
    and it made a lot of difference. Called a T-Bob ,They are avaliable on the net, made somewhere in USA.

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