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I just changed oil and serviced plugs, have some sort of leak, I thought exhaust leaks were white, this is tan could it be an oil leak the above pipe hose clamp is damp

BD7A6167-725F-4817-9F6F-261B3AC3E66C.jpeg

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1 hour ago, Danb said:

this is tan could it be an oil leak the above pipe hose clamp is damp

IMG_1446.thumb.jpeg.f2770c7d4e9119e359cc350d0551cb5c.jpegDan,

  Do you run LOP?..    It's a thermal reaction to the paint. 

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It doesn't seem to be leak related on my engine, but thermal effects on the exhaust pipe coating.  CYL#4 correct?.. same as my picture. 

If you think it is a leak, then put the CO monitor near it, that should go off quickly.  

Check that the valve guide injectors are tight to see if that is the source of the oil..   

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It doesn’t look like a leak with an origin escaping from a joint, or crack, or hole...

If it is a leak... A CO monitor would be a good tool...

Does look a lot like what PaulM has...

If that is a coating... is it staying on or does it need help?

Dan, Any JPI data to share? :)  (hotter than usual EGT on that tube?)

Lets ask @M20Doc... (stain on a Bravo exhaust tube question...)

Best regards,

-a-

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Only a guess, but oil leaking on the pipe as there is normally no coating on the pipes that I know of.

Clarence

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4 hours ago, M20Doc said:

Only a guess, but oil leaking on the pipe as there is normally no coating on the pipes that I know of.

I'm pretty sure that matte surface isn't pure iconel, so I'm assuming some sort of paint after it is welded.  It could be that the color is a combination of the paint, some oil leaking and the heat out of the exhaust port.   Both #2 and #4 cyls have had oil leaked before I noticed the orange patches.  Mostly on #4, but a bit on #2. 

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That is an interesting twist...

Similar color on the exhaust tip....

That would probably be the coolest part of the exhaust system..... still hot just cooler than every part up stream...

Before the turbo would be the hottest parts of the exhaust....

Inconel... is a nickel based stainless steel... so there is no ‘pure’ inconel... per-se....

It is pretty good at handling heat, and chemical environments...

 

Anyone know any exhaust welding shop contacts?  Or somebody at Lycoming?

We could ask them what this is when they see it?

 

If it is exhaust gas related... this would be more important to know about under the cowl...

 

Might be a variation of oil getting baked in an air environment....

A small drop of oil getting dropped on the outside of the pipe...

A small drop of oil getting delivered on the inside of the pipe...

 

Looks like it could/might get cleaned off...??? To see how quickly it returns...

  • Dan’s looks similar to something dripping and building up in the area... and possibly spreading
  • Paul’s, is in a similar place, shares some 3D characteristics... that, might be a high temp ceramic coating that may be coming off...   similar to JetHot coatings.... used on exhaust systems...
  • Stephen’s is possibly showing the end effect of the coating not being able to stick where the pipe has sharp corners or may have been cut after the coating was applied....

These are Only observations I have made about the three pics above...

They are PP thoughts only, not a mechanic...

Best regards,

-a-

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9 hours ago, drstephensugiono said:

90% at 32/2400 @19.7gal/hr TIT around 1580


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In the first Bravo I owned I used to run it at 32/2400. If I wanted to go faster i even ran it at 34/2400. Flight Safety in my initial Bravo training told me this was an approved power setting and the POH agreed. But after sitting in on Bravo forums at MAPA and talking to other Bravo owners, the last couple Bravos I've owned I run at 29/2400.

The high power settings came from the marketing department way back when trying to get the max cruise speed to 225 knots at FL 250. They would tell you that the TIO-540 in the Piper Navajo was pushed to 350hp, so really at 270hp the Bravo engine was practically idling. The only problem with that is that they are completely different engines, not sharing a single common part. The numbers looked great on the brochure, but those high settings printed on the visor push the engine too hard, they also take its toll on the exhaust. Bravo experts will tell you that the "Magic number" you're looking for is 53 (example 29 + 24 = 53) if you want to come close to getting TBO out of your engine and not get incinerated by a failure to the exhaust system.

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3 hours ago, drstephensugiono said:

At 29/2400 what fuel flow?


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18.0 with 1600 TIT

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I would call Acorn welding and possibly send them a photo.  I have found them extremely helpful and they know our exhaust pretty well.  I have a similar color on the tip of my exhaust.  On a side note, do whatever you can temp wise to preserve your turbo transition piece (the "T" part that connects to your 4&6 exhaust stacks as well as turbo).  None of the fabricators seem to want to work on it anymore and it's a $5K cast piece that you must buy from Lycoming...  

Edited by Davidv

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I would call Acorn welding and possibly send them a photo.  I have found them extremely helpful and they know our exhaust pretty well.  I have a similar color on the tip of my exhaust as well.  On a side note, do whatever you can temp wise to preserve your turbo transition piece (the "T" part that connects to your 4&6 exhaust stacks as well as turbo).  None of the fabricators seem to want to work on it anymore and it's a $5K cast piece that you must buy from Lycoming...  




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