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I have a 2006 CTSW with a 912ULS and have been plagued with this tiny oil leak that is making a complete mess of the airplane.  Loses about 0.1L of oil every 10 hours or so.  Can't seem to locate the leak as it doesn't seem to show up when we run it with the cover off and would require the engine to run at power.

The observations are, the leak seems to originate on the front right piston on the bottom.  No oil has been seen on the top end.  Ar first, we thought it was the valve cover o-ring; changed all of them.  We thought it was the torque of the block; we torqued all the bolts... Oil still leaks.  cleaned and wiped down the entire front end of the motor and took her up for a flight.  Oil seems to be coming out of the rods on the bottom, but can't trace it.  When the engine stops and we take the cowel off, you can see oil only on the bottom side.

The worst part is that it drips down during operation and sprays a long streak of oil all over the bottom of the aircraft.

Any thoughts?  I am attaching a photo of the bottom side of the front right cylinder.

Thanks in advanced!

Mark.

8138_1_IMG_2758.jpg (You do not have access to download this file.)
8138_1_IMG_2757.jpg (You do not have access to download this file.)
  • Re: Oil Leak on Right Front Cylinder Head

    by » 3 months ago


    IT LOOKS LIKE IT'S LEAKING FROM THE VALVE COVER. I KNOW YOU SAID YOU PUT ON NEW O-RING AND TORQUED PROPERLY I BELIEVE 90 INCH POUNDS.

    THERE IS A POSSIBILITY THE VALVE COVER ITSELF MAY BE WARPED. I CAN ONLY SUGGEST YOU PUT NUMBER 3 VALVE COVER ON NUMBER ONE AND ONE ON THREE. TEST FLY AND SEE IF OIL LEAK HAS CHANGED LOATION. JUST LOOKING AT PICTURES THIS IS ONLY THING I CAN SUGGEST SHORT OF MAJOR CYLINDER WORK. 

    PUT NUMBER ONE VALVE COVER OR THE ONE I SEE OIL DROP ON  ON A FLAT MARBLE COUNTR TOP OR FLAT HARD SURFACE AND IT SHOULD HAVE NO WOBBLE. HOPEFULLY OTHERS WILL HAVE BETTER IDEAS HOW TO MAKE SURE VALVE COVER ITSELF SOMEHOW DID NOT BECOME WARPED CAUSING BAD SEAL AT O RING EVEN WHEN PROPERLY TORQUED. 

     

     

     

     


  • Re: Oil Leak on Right Front Cylinder Head

    by » 3 months ago


    Also make sure there is no pin hole or crack at bottom part of valve cover. You might need to take paint off at edges to make sure. Just a thought. Make sure surface of cylinder is polished/clean to include inside valve cover where o ring makes contact. Follow procedure in maintenance manual on changing o rings on valve covers. 


  • Re: Oil Leak on Right Front Cylinder Head

    by » 3 months ago


    Last thing I can suggest is take the valve cover off where leak is suspected. Buy at auto part store thread sealant permatex number 59235 high temp 400 F. PUT some on o ring saturated it and install. See if it solves problem. I have had very good results in other applicaions with this product It does not get hard. This may solve the problem. I believe some or manual suggest using loctite 598. Try above with permatex it want hurt anything. Just a suggestion and others may object to this. I can only suggest this through my experience. 

     

     


  • Re: Oil Leak on Right Front Cylinder Head

    by » 3 months ago


    The drip underneath the valve cover does not seem to explain the rather big amount of oil on the ignition cables and their red tube. Perhaps you have to fix two sources of oil.


  • Re: Oil Leak on Right Front Cylinder Head

    by » 3 months ago


    What’s that cylinder’s spark plug look like? There are dye additive such as this https://www.aircraftspruce.com/catalog/topages/aerobrite8oz.php  you could use to find the leak- but you also need a UV light.  Recommend you first confirm no compatibility issues with an authorized Rotax Service center representative. 


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