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After burping the engine, we fill it to halfway up the flat part of the oil dip stick

Where is the best place to have the overflow tube? (does anyone have pictures of theirs)

Is it recommend to put a small tank at the end of the overflow tube to catch the oil, coming out during flight?

8944_1_IMG_7577.JPEG (You do not have access to download this file.)
  • Re: Oil tank overflow tube leaking

    by » 9 months ago


    I just have a length of clear urethane hose that I have cable tied to the engine mounting frame. The cut end is just out of the air flow. I once attached a bottle to the bottom to see if anything ever came out and it didn't.

    I've looked through my photos but none of them clearly show the hose. Just route it so that there are no kinks and it should be fine.


    Thank you said by: Mike Butram

  • Re: Oil tank overflow tube leaking

    by » 9 months ago


    There should really never be any oil coming out of the breather tube unless you have overfilled the tank, or have some other kind of problem.

    lf you were to put something on the end of the tube, nonetheless, you'd have to make sure it remained unsealed and open to the air.


    Thank you said by: Mike Butram

  • Re: Oil tank overflow tube leaking

    by » 9 months ago


    No oil should be coming from the tube unless the tank is over filled. Vapors, boiled off contaminates and air will come out during flight because this is the engine's only breather outlet for the air that pushes the oil back to the tank off the bottom of the crankcase. Most have the tube run down the back of the fire wall and down to about 1" -1.5" inside the cowl. You don't want it out in the air flow.


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


    Thank you said by: Mike Butram

  • Re: Oil tank overflow tube leaking

    by » 9 months ago


    Hi Mike

    In your picture the oil tank looks to be very high on the firewall.  Check this against the spec in the installation manual to be sure.  It is possible that you are not getting all the oil from the crankcase out and back into the tank when you "burp" it with the prop.  

    The vent line for the oil tank also is shown in the installation manual.  It is your only crankcase ventilation point so is very important to be sure that the vent line is not in an area of low pressure while running.  As with any vent line a notch must be cut into the line before it terminates at the bottom.  This is to prevent any accumulation of ice or debris from blocking the line. In addition it also will limit any draw from low pressure air if the line is in a low pressure zone such as into the belly airflow coming back from the prop.  This airflow might be drawing the oil vapour from the tank by creating low pressure at the top of the oil tank cavity.  

     

    Cheers


    Thank you said by: Mike Butram

  • Re: Oil tank overflow tube leaking

    by » 9 months ago


    You're right about the tank. I should have looked at the picture before I commented. That's way up there like the old Kitfox aircraft. I agree with the Wizard :) that you may not be getting all the oil up there because the tank is higher than the installation manual specs. This means the oil coming out the bottom of the crankcase is more likely not getting all the way back up your return hose. Only the air is. Then you see a low level on the dip stick, but in reality the oil is there just not getting back all the way up hill through the hose and back into the tank.. The oil just allows the air to bypass it as it tries to push the oil up hill through the hose. Now if you added oil to the tank it is over filled and when you start the engine there is enough air and oil to get all the way back to the tank which causes an over flow scenario. 


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


    Thank you said by: Mike Butram

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