M20M Bravo oil leak around exhaust flanges

[HighFlyer]

I have a 500 hr SNEW engine on my 1999 Bravo and recently developed oil leaks around some (not all) of the exhaust flanges (annual inspection time).  See the attached photos for the flange and deposits on the the EGT probe and clamp.  As this is a Bravo, the oil deposits are worse on the lead cylinder in the daisy chain that injects oil on the exhaust valve.  The Bravo engine runs an oil line to the number 2 (pilot side front) then Tees off to the Number 4 then Tees again to the Number 6 cylinder.  Its in reverse order on the copilots side and runs to the number 5, then tees off to the number 3 then tees to the number 1 cylinder.  The The oil leakage is most pronounced on the first cylinders ( 2 and 5) of the daisy chain, with less on the second cylinders (4 and 3) and none on the final cylinders (6 and 1) of the daisy chain.  

There has always been a very small amount of oil leaking around the number 2 cylinder exhaust flange and depositing on the EGT probe since the engine was new with 0 hours in 2011.  However, the airplane is in for annual inspection and the leaks are more pronounced since last year and the last oil change. 

Compression is very good (high 70's) and oil consumption hasn't changed this past year.  

Has anyone had similar experience?  Thoughts? 

[LANCECASPER]

That kind of leaking is unacceptable and dangerous around the exhaust and turbo. That much oil could easily catch fire.

Ask me how I know, but it is very easy to get the oil-cooled cylinder hoses cross threaded just a little on the T fittings. They look like they are on straight and then you run it up and there is an oil leak. The t-fittings are the first place I'd look since the oil will run down through the cylinder fins and make it appear as if it's coming from some other place.

 

 

Another place that it is very difficult to get the hose on straight so that it doesn't leak is the Turbo inlet. The threads on this fitting (see arrow) on mine were bad since they had been cross threaded. This fitting (Lycoming part number 02A21126) is very difficult to find. I bought one yesterday and had it overnighted from Preferred Airparts. They had three left in stock. I couldn't find another one in the country. Mine was leaking after runup yesterday and after the fitting and a new gasket (lycoming part number 77813) it is dry today. 

[HighFlyer]

Thanks for the information, it is very helpful.  I agree this amount of oil is disturbing and dangerous.  It was not present at the last oil change ~25 hours ago.  

To the best of my knowledge, the oil lines have not been removed since the engine was new.  Somewhat surprising they would start leaking now, but stranger things have happened.  

[carusoam]

Welcome aboard, High Flyer.

Since you are reviewing small issues that can be dangerous for you and your engine...

Are you familiar with the v-band clamps on the Bravo exhaust system?   They have some limitations that not everyone is  aware of... so I bring it up often to Bravo owners as they come on board....  

Best regards,

-a-

[HighFlyer]

13 hours ago, carusoam said:

Welcome aboard, High Flyer.

Since you are reviewing small issues that can be dangerous for you and your engine...

Are you familiar with the v-band clamps on the Bravo exhaust system?   They have some limitations that not everyone is  aware of... so I bring it up often to Bravo owners as they come on board....  

Best regards,

-a-

Yes, very familiar.  I had to replace them twice on the original engine.  So far, no exhaust leaks on this one after 500 hours

[IvanP]

Resurrecting an old thread here. @HighFlyerDid you find out what was the source of the leak? What was the corrective action. 

I just discovered the same symptoms on my Bravo yesterday while changing oil (about 80 hrs on the engine SFRM). I checked all the top oil line connections that are prone to leaks, but all appears dry on top. 

REgards,

Ivan

[Fritz1]

Tighten the oil injector at the cylinder until it stops leaking

[FoxMike]

I would suggest you look at the exhaust gaskets.  You maybe be seeing oil coming out the exhaust because the exhaust gasket does not fit correctly.  Do not over torque the nuts on the studs trying to stop the leak.