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  #1  
Old 10-15-2010, 02:45 PM
L'Avion's Avatar
L'Avion L'Avion is offline
 
Join Date: Apr 2007
Location: Memphis
Posts: 159
Default IO-360 Strange Start Problem

IO-360, high comp pistons, starts normally, then fumbles, runs rough, and #2 EGT is abnormally low; condition doesn't smooth out. Engine shutdown, wait a couple minutes and restart; and restart cures the problem - no further problems. Plugs have been cleaned (look good) and the fuel line to #2 has been removed, blown out clean --- same problem persists. Mystifying!

Any ideas?

Barney, in Memphis
RV-4 flying
RV-3 flying
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  #2  
Old 10-15-2010, 03:41 PM
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Walt Walt is offline
 
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Default

I'd be looking for a stuck valve.
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  #3  
Old 10-15-2010, 04:11 PM
Kyle Boatright Kyle Boatright is offline
 
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Location: Atlanta, GA
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Potential induction leak. Something may be cracked and have a gap when it is cold, then the assembly heats up, grows due to the heat, and seals the gap.
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  #4  
Old 10-15-2010, 08:00 PM
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L'Avion L'Avion is offline
 
Join Date: Apr 2007
Location: Memphis
Posts: 159
Default

Walt,

Thanks for the heads up. I should have thought of s sticking valve myself. After reading the Lycoming Flyer, Key Operations -1 at: http://www.lycoming.com/support/tips...Operations.pdf I am even more suspicious of a sticking valve. I will so advise the owner of the aircraft of your advice.

Thanks,
Barney, in Memphis
RV-4 flying
RV-3 flying
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  #5  
Old 10-24-2010, 02:54 PM
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L'Avion L'Avion is offline
 
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Location: Memphis
Posts: 159
Default Stuck Exhaust Valve = Culprit

Engine has 4 into 1 exhaust: We pulled the prop through while listening with our best ear at the exhaust pipe. Three cylinders exhausted with a BIG POOF, and the culprit just hissssssed!

Barney, in Memphis
RV-3 flying
RV-4 flying
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  #6  
Old 10-24-2010, 03:07 PM
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Mike S Mike S is offline
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Location: Dayton Airpark, NV A34
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Rope trick time.......
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VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

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  #7  
Old 10-24-2010, 07:29 PM
LuisR LuisR is offline
 
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Location: St Lucie County, FL
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Default

Sounds like a stuck valve.

Whats "the Rope Trick" Mike?
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  #8  
Old 10-24-2010, 07:56 PM
tturner tturner is offline
 
Join Date: Jul 2008
Location: Fayetteville, GA
Posts: 164
Default Morning Sickness

The Dec 2010 online issue of Kitplanes has a very good article explaining the problem and how to fix it.

Title of article > Morning sickness: It?s about sticking valves.
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Fayetteville GA
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  #9  
Old 10-24-2010, 08:32 PM
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Neal@F14 Neal@F14 is offline
 
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Location: Wichita Falls, TX
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Textbook symptoms of a stuck exhaust valve.

Since it's a high compression engine, I'd advise borescoping it to see if the exhaust valve isn't burned. The rope trick, or even "staking" the valve with the rocker cover removed may only temporarily postpone the inevitable need to pull the cylinder off and send it to a cylinder shop for a proper fix.
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  #10  
Old 11-01-2010, 02:11 PM
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L'Avion L'Avion is offline
 
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Location: Memphis
Posts: 159
Default Problem Fixed - Back in the Air

The problem was a sticking exhaust valve on #2. Valve was dropped into the cylinder, dragged out a the lower spark plug hole, and the stem was cleaned. Valve guide was reamed, and everything was reassembled - ground run & flight test, A-OK. The other three exhaust valves will be checked and the guides reamed (if necessary-sticking at all) at the next oil change.

Link to some helpful valve poop:
Everything You Ever Wanted to Know About Lycoming Valve Failures
http://egaa.home.mindspring.com/valves.html
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