Hello Guys, 

So yesterday I got to work on my 601HDS with What I believe to be a GEN 1 Jabiru 3300 engine, and as I was about to start my engine for the first time ever, I noticed fuel mixed with Oil coming out of my Air Filter Box, which after chasing, I noticed that it was coming from the Bing Carb.

As previously mentioned I purchased this Aircraft at about 90% completion, and it had been in the process of building for at least 20 years prior to me buying it. With that being said, about 1 month ago, I put about 1 cap of Mystery Oil in each cylinder to help loosen things a bit since the brand new engine had never been started. Yesterday I added 1 more cap of Mystery Oil to each cylinder again before turning the prop by hand, and everything looked to be smooth. 

I took the plane outside the hangar, and fed some fuel in it, and that’s when I noticed the Fuel and the Mystery Oil Leaking from the bottom of the Bing Carb.

I believe the leaking issue might be a simple cracked/dried old gasket, but my biggest concern is still the presence of the Mystery oil in the Carb. 

I took the Carb out, and inspected it, and it looks good to me, but again, it’s new, so not sure what’s going on. I might have to have it re-built. 

Thanks in advance for your help!

Adel Bazzi

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The only path that I can think of is the MMO was pushed thru an open intake valve when the engine was hand turned.  Then down thru the intake runners into the manifold ( I think Jabiru calls it a Diffuser ) and then into the carb.  The presence of MMO in the carb isn't too worrisome to me.  However, the fact that fuel was running out of the carb indicates to me that the float is stuck open or the float valve can't seal.  If you haven't already removed to float bowl, then that's were I would start looking.

There is a source if Bing carburetor parts in the US, search " bingcarburetor.com", they have the customary disclaimer for aircraft use, but never failed to supply parts to me.

Thanks for the Reply Dave. I think you’re right. I am not longer too worried about the MMO.

The fuel leak seemed to be from the Bottom Gasket, which might be dry and cracked due to its age. I am going to try to re-build the Carb to be safe. 

Thanks again!

Adel Bazzi


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