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01-15-2015, 05:44 PM
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Join Date: Apr 2008
Location: Indianapolis, IN
Posts: 1,069
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Sticky exhaust valve
So I have experienced on few occasions that meet every indication of a sticky exhaust valve on number 4 of my angle valve 360. It first appeared at Oshkosh, then reappeared in the last month or so. Now that it's reappeared it has been eating at me an I'm afraid to fly until it's checked and reamed. I have read every service bulletin, service letter, online write up ect....describing the process of dropping the valve and reaming the guide, til I'm blue in the face. Not doing anything like this before I finanlly reached out to an "ol timer" a/p who said he would help me. But he said the only way is to remove the cylinder. I told him about doing it cylinder on and said no way to do it correctly. So...do I go ahead and let him help me remove the cylinder, which is unnecessary, or find another a/p for assistance.
__________________
Ryan Allen, CFII
RV7 N612RA, flying since july 2012
E-170/175
RV10 Tail Kit complete, Wings 90%, fuse on order
Acro Sport 2, building
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01-15-2015, 05:54 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,767
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Have you done the 'wobble test'?
Get someone else to help.
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01-15-2015, 06:17 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,515
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Maybe RocketBob will weigh in here, but here goes. If the job can not truly be done without removal of the cylinder, and you/he have the tools for reassembly. It is a simple removal and reassembly. The only cost difference are the gaskets, and there is a very small risk of ring breakage with any cylinder install. I would not hesitate to do it this way.
You should discuss with your A/P what is "right" about the cylinder removal vs doing in cylinder, and satisfy yourself to the differences.
I love seeing inside the engines and gaining confidence with it's condition, but that's just me. 
__________________
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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01-15-2015, 06:31 PM
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Join Date: Sep 2009
Location: St. Louis, MO
Posts: 1,785
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I had this same issue a long while back, same engine. I followed the lycoming sb. I did not remove the cylinder. First of all, you can check the valve and determine if you have an issue without removing the cylinder. Reaming the guide insitu is easy. I would have someone who has done it before get you started, or assist you in performing the operation. It is not difficult! You need a ream and a valve spring compressor, so find someone who has the tools and get started!
__________________
Bill Peyton
RV-10 - 1125 hrs
N37CP
First Flight Oct 2012
Aviation Partners, LLC
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01-15-2015, 06:44 PM
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Join Date: Jan 2006
Location: Winston-Salem, N.C.
Posts: 1,210
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Its a very common and "normal" process on the smaller Continentals. I have performed it many times (I'm an AP/IA), and never had negative results. I cant speak for your exact situation, but the process is designed to "clean ream" deposits from the guide. Its weird the first time the valve drops into the cylinder, but mechanical fingers, and a flashlight and its right back in. I usually use compressed air blowing into the cylinder while reaming to help keep debris minimized.
__________________
Bill E.
RV-4/N76WE
8A7 / Advance NC
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01-15-2015, 07:25 PM
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Join Date: Aug 2007
Location: Wichita Falls, TX
Posts: 2,182
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Removing the cylinder is a positively known way to get the valve issue fixed plus it gives you the opportunity to inspect some of your cam lobes as well.
__________________
Neal Howard
Airplaneless once again...
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01-15-2015, 08:02 PM
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Join Date: Apr 2008
Location: Indianapolis, IN
Posts: 1,069
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I guess my biggest beef in removing the cylinder is the several hours it will take to remove my baffles.
Have not done the wobble chck but I figure that will be done prior to dropping the valve. I do have a compression spring tool but no reamer. I called lycoming tech support and they told me I would need .4995 to .5005 to the finish id. I have found several sources online to buy such reamer.
__________________
Ryan Allen, CFII
RV7 N612RA, flying since july 2012
E-170/175
RV10 Tail Kit complete, Wings 90%, fuse on order
Acro Sport 2, building
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01-15-2015, 08:32 PM
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Join Date: Apr 2012
Location: Tampa (BKV)
Posts: 926
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You do not need to remove the cylinder to ream an exhaust valve. Find a newer A&P.
__________________
RV-8 Flying
1,235th flying RV8
SARL Race#95
SnF Homebuilt Judge
2015 Sun n Fun Kit Built Reserve Grand Champion
2015 Oshkosh Kit Built Champion
2015 Jeffco Kit Built Grand Champion
2014 Oshkosh Outstanding Workmanship Award
Broken Warrior of the Jarhead Clan
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01-15-2015, 09:07 PM
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Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,428
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Don't know what your symptoms are but if the problem eases upon warming up, you might try changing the spark plug, if you're using Champions. One gave me indications that looked like a sticking valve that went away after getting the engine warm. Installed a new plug and it's been fine.
Dave
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01-16-2015, 07:01 AM
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Join Date: Mar 2009
Location: Rochester NY
Posts: 669
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The Lycoming procedure is described in their service instruction ( http://www.lycoming.com/Portals/0/te...20Sticking.pdf )
If I had a choice and could avoid pulling the cylinder, I would not pull it off. On the other hand, if there was time enough on the engine that I could get a look inside and it would be meaningful to do so, then I would. The Lycoming service instruction for installation of the cylinders, I believe, was 1029 - I'd have to check to see what the latest version of that would be.
Dan
__________________
RV7A (N7101) - Flying 10/2008
CFI- SE/ME/Inst
A&P
KC2ZEL
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