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09-11-2013, 11:25 AM
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Join Date: Nov 2009
Location: Paris, France
Posts: 24
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Ashes in the exhaust pipe
Hi there!
After a 2 hour flight at FL95 I was surprised to find a fairly sizable deposit of white/grey ashes when rubbing my finger at the end of one of the exhaust pipes(and not both). The engine is a carbureted O-320. Anyone has an idea of where does this come from? Thx for tips.
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09-11-2013, 11:36 AM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,562
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Lead deposits.
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Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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09-11-2013, 11:55 AM
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Join Date: Nov 2009
Location: Paris, France
Posts: 24
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Thanks Bob!
is it something I should be worried about ? why just on one exhaust and not the other?
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09-11-2013, 12:03 PM
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Join Date: Nov 2008
Location: Shreveport, LA
Posts: 1,002
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white/gray color
I had always been told if you run your finger in your exhaust pipe and there is white/gray dust on it, that means you are running your engine the way it should be run.
Can anyone verify or debunk that?
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09-11-2013, 12:07 PM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,562
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If you're only getting lead deposits on one pipe that means one of the cylinders on that side of the crossover is pumping a bit of oil past the rings which is not unusual.
Grey pipes are good if running 100LL.
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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07-19-2014, 05:06 PM
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Join Date: Oct 2008
Location: Utah
Posts: 8,145
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Need an exhaust reader
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07-19-2014, 05:32 PM
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Join Date: Jan 2005
Location: Yorkshire, England
Posts: 2,048
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Relative ?
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"I add a little excitement, a little spice to your lives, and all you do is complain!" - Q
Donated in 2020 
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07-19-2014, 06:26 PM
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Join Date: Aug 2007
Location: Wichita Falls, TX
Posts: 2,182
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Quote:
Originally Posted by Vlad
What are those brownish streaks?
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Possibly lead bromide deposits from the combustion byproducts of 100LL?
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Neal Howard
Airplaneless once again...
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08-02-2014, 07:13 AM
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Join Date: Sep 2011
Location: WV22
Posts: 849
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Still better than the "banana in the tail pipe!"
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RV-4 0320\D3G 160, Whirlwind 200GA 70".
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08-02-2014, 02:27 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,514
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Just a wild maybe but iron sulfate? A solid material resulting from sulfur in fuel combined with condensed exhaust water forming sulfuric acid that dissolves minute amounts of Fe in the exhaust pipe then, evaporates as the pipes warm and leave the streaks. The change in color where the streaks begin seem to be the hot zone of the exhaust and the border is where the air blast from ahead has cooled that part of the pipe, the tip.
If this is correct then warm water will completely dissolve it.
There used to be much more sulfur in fuels than today. I have seen something similar in diesel exhaust pipes using high sulfur fuels across an oxidation catalyst in below zero air.
Or- it could be something else entirely and this is all my vivid imagination.
Welcome back Vlad!
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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