Oil spray over windshield and top cowling.

[N201MKTurbo]

I wouldn't try to loosen that fitting. When I rebuilt my engine I tried to remove it. I couldn't. I talked to the case shop and they said they had a guy who was an expert at getting them out. He uses a propane torch and strategically heats the case to get them out. I wouldn't suggest taking a torch to an assembled engine.

That fitting is a bit of a problem. That fitting must be clocked just right. If it gets tight a few degrees past where you need it, you have to horse it around another turn. That can be brutal. You could hit it with a tap to open it up a bit, but there is no going back on that. The only way to fix that is to have it welded, which is a complete teardown.

[PT20J]

2 hours ago, Pinecone said:

Then don't use NPT threads.  Just straight threads and an O ring or gasket.

[Yetti]

I kind of don't think that fitting is your problem.   They usually have a drop of oil on them if leaking.   It looks like that is the prop control oil line.   There is an SB to make sure you have proper nut on it.

 

Check your drain back tubes.   they are usually the problem.

[cliffy]

That particular fitting and tubing is for prop control oil

It is HIGH pressure from the governor  (IIRC 600 psi) That is why the tubing needs to be checked from one end to the other 

for cracks and wear from clamps and attachments per the AD.       If it lets go you lose oil quickly

One also needs to check the flare at the end of the tubing to look for cracks in the flare and wear.  Used to see lots of them on 

3000 psi hydraulic lines on Boeings etc. 

An AD specifies to change it from original aluminum elbow fitting (blue) to steel (should be black in color, check with magnet)

If loose change to new steel elbow and tighten to the low side of the proper torque and see if you have anything near

good alignment with the tube B nut

Hopefully it is short of correct alignment and a little more torque will correct it. If it is so short of alignment that correct

high torque value can not bring it into alignment then you are left with trying another new fitting hoping for better alignment.

BTW what does Lycoming Overhaul Manual say to use on the threads for sealant? 

AD attached here        http://www.yeeles.com/Reference/AD/Lycoming/90-04-06 R1.pdf

Consult with your A&P

[carusoam]

Summary…

1) oil drip at…

2) the interface of the engine and a 90° elbow fitting with NPT threads…

3) Use proper Teflon sealant… not thread tape… 

4) Thread tape has a tendency to show up later in unexpected places…

5) Use caution taking the fitting out, and tightening it again… it is steel threads in an aluminum thread…

6) differential heating and cooling may help to loosen the fitting…

7) this fitting supplies engine oil from the Governor to the prop…

8) If the leak gets worse, it can empty the engine of its oil

 

PP writing only, not my ideas at all…

Best regards,

-a-