Christen/Lycoming Inverted Oil Sump Drain Fitting

[Bartman]

Hi all,

Sorry for the multiple inquiries about the inverted oil system! The '79 8KCAB that I bought recently has an AEIO-320 -E2B in it and it has the Lycoming (nee Christen) inverted oil system. My A&P/IA friend reminded me to clean the oil pump suction screen when I installed the B&C oil filter adapter kit this week and it has been a quest to determine if the inverted oil system is actually installed correctly. To start out, there is an o-ring missing from the big sump plug which, I think, means the system will suck air when inverted so no oil pressure when upside down.

In tracing the oil lines, the one from the bottom of the oil valve is supposed to go to a fitting that should be where the drain plug was but it goes to the back-left side wall of the sump.

Would it be possible for someone to double check the routing of their oil line from the bottom of the valve on the firewall? Is the tee fitting actually screwed into the sump where the drain was? Is there a quick drain on the extra leg of the tee so oil can still be drained from there? This tee should also be where the suction screen is located so, after draining, the whole tee needs to be unscrewed, correct?

Thanks in advance for any help!
Bart

 

[Bob Turner]

Not sure I can help. My 1977 has a Christen system like the "modified" drawing in your other thread. The plug (#805) is held by a long screen horizontally inserted on the right rear of the sump. It has 10-32 threads, which means you can easily insert it with the proper O ring and a very long AN-3 bolt.

I can tell you this: when that single O ring starts getting weak, inverted flight starts to get adventurous! Your first hint may be zero pressure when you roll rightside up. Mine fails at ten year intervals, so I have forgotten some of the details.

 

[Sully]

Does this help?
Sorry, just saw this post first.