Hello everyone.
I am using Google Translate from Spanish to English.

I need help to fix an oil leak.

It is a Rotax 912 ULS engine serial number 6777230 installed in a Tecnam P92. The area impregnated with oil is the lower part of the two semi-crankcases of the engine. As I did not discover the specific area of ​​the leak, I made a mixture of talcum powder and alcohol and with a brush impregnate the entire lower part of the two crankcases, after cleaning with gasoline and drying. Putting the engine back into operation, I see a leak in two screws in the lower part of the crankcase.

What would be the best solution to this problem.

Engine parameters all normal.

Thanks everyone for your help

9395_1_C7FB8248-DC74-47AA-8257-141ADA5C9D8F.jpeg (You do not have access to download this file.)
  • Re: Help with oil leak

    by » 2 years ago

    Try some silicone sealant on the bolt shank.

  • Re: Help with oil leak

    by » 2 years ago

    Morning, I’ve not dealt with an oil leak there before but my thoughts are it’s two possibilities:

    1) The washer and bolt has retained oil. It’s VERY hard to actually clean oil out of an oil soaked bolt so it can appear to ‘leak’ when it’s actually just old oil hiding in the bolt/split washer. 

    2) My understanding is that the only reason that bolt could leak is if the crank case seal has broken down. If this is the case you have a much bigger issue. The crank cases should be split, inspected and re sealed if the cases haven’t fretted/chaffed. 

    Simply sealing the bolt might fix the leak but not establish the cause 


  • Re: Help with oil leak

    by » 2 years ago

    I just went through this here is my path over 2 years on a fresh overhaul

    first the crank seals due to high crank pressure so check that

    I did have a bolt leak on the upper rear, silicone did the trick i though .Im not sure those lower bolts have oil pressure.  

    most oil stopped but i still had some between the right cylinders and fins. im thinking oring on head bolts? before i pulled the cylinder I had to check better. Cleaned the engine with brake cleaner and applied spray on foot powder. Took it around the pattern once and inspected and found the area of leakage right away . top over number 1. 2 small cracks not even visible with the eye. It was the older crankcase which is prone to cracking.  Oh the hook for a new engine block now and an end to my season. we learned a lot


    good luck

  • Re: Help with oil leak

    by » 2 years ago

    Oozing bolts like your picture are fairly common from what it have seen over the years and usually aren’t a big deal. Most never see or find them unless they do what you did. I use Desenex foot spray powder to find things like this. I wouldn’t lose any sleep over it, but if you want to fix it remove the bolt and apply some Loctite 243 blue to the threads. Coat them fairly well and put a dab on the washer face and on each side. It should take care of it.

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

    Thank you said by: RotaxOwner Admin

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