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Dear Forumites

After the last oil change of my Hawk Arrow 2
the oil tank was overfull, at the very top of the
flat part on the dipstick. I left it at that.
Today, after landing from an uneventful 2hr
flight through light rain I noticed the smell of
oil. I found that the engine lost at least 50ml
through the oil tank vent. It was in a puddle
underneath the plane and all over the tail. The
tank was brimful. I obviously didn't add any
oil. Where does the extra volume come from?
To matters a bit more of a challenge, I'm three
hours from my home port.

The fuel pressure was low, but I put it down to the fuelpressure sensing setup that is always erratic,
but not that low. It felt like the engine revs
were unstable, but always willing to return to
full power. Temperatures were a low normal.
The oil wasn't milky but I didn't pick up a
smell of petrol. But I wasn't trying to either.
  • Re: Rotax 912UL oil overflowing. Why?

    by » 11 years ago


    Hi Arthur,

    Here are two common possibilities. You may have had some diesel fuel in your other fuel and that will migrate back into the oil tank and cause the level to rise or is it possible that at the last oil change you actually left a little more in the oil system and now it's over full? What type of fuel are you using, 91 octane or 100LL?

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


  • Re: Rotax 912UL oil overflowing. Why?

    by » 11 years ago


    Couldn't possibly be so much diesel. I use unleaded mogas.

    My installation doesn't burp easily. I later ASSumed that the oil return in the tank doesn't go deep enough into the tank to make it burp.

    I forgot to mention, the oil change was 20hrs ago, any excess oil should have been in the tank long ago?
    Water in synthetic oil (I use Fuchs, can't remember the type) seperates much easier, perhaps masking the milky colour of water in oil?
    The new type petrol pump (not sure about the old type) has a drain pipe to drain petrol out of the pump in case of a ruptured diaphragm?

  • Re: Rotax 912UL oil overflowing. Why?

    by » 11 years ago


    Don't discount the diesel. Get a fuel sample and get it tested or take an oil sample and do the same. There have been a few here that were surprised. You can always just drain the fuel and use it in your car and use fresh.

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


  • Re: Rotax 912UL oil overflowing. Why?

    by » 11 years ago


    Agree with you abb. diesel in fuel we had that problem. Very small amount vill rise the oil level.
    Eyolf

  • Re: Rotax 912UL oil overflowing. Why?

    by » 11 years ago


    Diesel in the fuel.

    Drain and flush your fuel tank and fuel lines with fresh fuel.

    Flush your fuel can with fresh fuel. If you've not used diesel in your fuel can, change your fuel station.

    Use the old fuel in your wife's car :-))

    Do another oil change as your oil is contaminated and will not be lubricating your engine properly. You could do some serious damage if you don't change your oil as soon as.

    I would do two oil changes to get the all the contaminated oil out.

    Mark

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