Diagnose my first oil leak after recent overhaul...

[DXB]

I’m requesting a little diagnostic input on the first oil leak to arise on my engine post overhaul. It is at 140 hrs and just under 11 months SMOH and has functioned flawlessly so far.  Today, when I reduced power to idle just before landing, I got a sudden little spritz of oil mist on the middle of the windscreen.  Upon landing, I noted a tiny bit of oil running back along the front of the top cowl.  Upon examining carefully under the cowl, it appeared immaculate – no oil to be seen (so it must not be a big leak).  The only exception is in the picture attached. There is oil that appears to be running down from the fitting connecting the prop governor oil line to the right front of the case.  This is a strip of oil from the fitting down the right front side (pic attached). I don’t see oil anywhere else.  Can one be confident the leak is from this fitting?  If that’s the case, I’m a bit surprised there’s no oil blowing back across the base of cylinder #1.   What is the best course of action here?   I also wondered if the leak might be from the front crankshaft seal, but I would expect oil on both sides of the engine in that were the case.

 

[Jsno]

I would need to see another picture.  This one shows nothing.

[47U]

33 minutes ago, DXB said:

I also wondered if the leak might be from the front crankshaft seal

Without an obvious leak after visual inspection, the crankshaft seal is the first place I would investigate.  It’s hard to see, but run a clean paper towel underneath the crankshaft on the backside of the starter ring gear.  If that’s clean, maybe pull the spinner and see if there’s any evidence of the prop leaking.

The prop governor oil line fitting might be leaking a little, but I don’t think it’s the source of your spritz.  

Years ago, I had the same spritz on my C model (narrow deck) under the same flight conditions.  It was the crankshaft seal.

(The safety wire on the alternator support arm looks to be neutral… could be parallax in the view… ummm, I apologize for mentioning it.) 

[Shadrach]

When was the prop overhauled? Do you see any oil on the face (backside) of the prop blades?
It’s hard to diagnose oil leaks online, but if I had to bet it would be on a blob of grease coming from the prop. Does not mean that the seals are herniated. Occasionally a prop hub will throw a little grease. It can atomize in the prop wash.

[Bartman]

Mine leaked there after a few hours on my overhauled engine. The pipe threads were not very tight. A bit of sealant fixed it. I think it was just a small drop of Permatex Aviation. Mine did not spray, but it is always possible to have two leaks. 

[DXB]

20 minutes ago, Shadrach said:

When was the prop overhauled? Do you see any oil on the face (backside) of the prop blades?
It’s hard to diagnose oil leaks online, but if I had to bet it would be on a blob of grease coming from the prop. Does not mean that the seals are herniated. Occasionally a prop hub will throw a little grease. It can atomize in the prop wash.

Prop was IRANd 140 hrs ago, same time as engine overhaul.  Back of blades appear immaculate.

[Shadrach]

16 minutes ago, DXB said:

Prop was IRANd 140 hrs ago, same time as engine overhaul.  Back of blades appear immaculate.

Well, if you can’t see where it’s coming from the only thing you can do is clean everything up and wait for a clearer (dirtier) picture to emerge.

[takair]

What 47U suggested.  See if the inside of the flywheel has a slime of oil in there.  I had this happen after overhaul, in my situation it would occur every 30 hours…..it takes that long to build up enough to splatter.  

[DXB]

1 hour ago, Jsno said:

I would need to see another picture.  This one shows nothing.

Try this one - cropped a bit, adjusted contrast, circled with red oval.  You'll have to take my word for it that it is the only oil to be found on the engine or anywhere under the cowl.

[Fritz1]

Clean thoroughly with mineral spirits, spray with dye penetrant developer, run engine to get 150 dF oil temp, shut down and look for oil trail

[Jsno]

3 hours ago, DXB said:

Try this one - cropped a bit, adjusted contrast, circled with red oval.  You'll have to take my word for it that it is the only oil to be found on the engine or anywhere under the cowl.

When I overhauled my IO360A1A, DIco had welded that area and tapped the hole.  It was a straight thread and the fitting was a pipe thread.  I bought a straight thread fitting ewwith an O-Ring seal and it worked great.  The previous overhaul had installed the pipe thread fitting with sealant.  Not good.  May be why it was cracked.  This could be the source of your leak.  Remove the fitting and check the threads on the case and the fitting to see if they match.

[47U]

6 hours ago, DXB said:

Try this one - cropped a bit, adjusted contrast, circled with red oval.

Sorry for revisiting…

When you photoshopped the image, it might (?) appear that the prop governor oil line B-nut is blue (aluminum)?  Comparing the color to the fitting in the case, which looks to be black (steel).  There was an AD to replace the lines with aluminum B-nuts with lines assembled with steel B-nuts.

I was a victim of this… during my AD/logbook verification, the logs said the AD was complied with.  But, one of the local (friendly) RV mafia consortium paying a visit to my hangar noticed the blue B-nut and was kind enough to mention it to me.  I queried the previous owner and the story was that yes, the line had been changed per the AD, but later inspection showed that the line was chaffing, which is an issue if you don’t order the line specifically to fit the Mooney.  So the mechanic put the old line back on with, I’m assuming so as to not ‘ground’ (!) the aircraft, and that he would order a new correct line and change it at a later date.  Which apparently never happened.  Previous owner reimbursed me for the new line.

Picture from 2010… When I removed the line, I found the generator mount bracket had a broken ear.  It had been welded, but broke again.  The new mount bracket was a lot thicker metal.

[Pinecone]

Clean engine with mineral spirits.  Add some UV dye to the oil.  Start, run up to 2000 RPM for 2 minutes and shut down. 

Check for leak using UV light.