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  #11  
Old 05-12-2015, 03:14 AM
rwtalbot rwtalbot is offline
 
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Quote:
Originally Posted by kiwipete View Post
Interestingly I have just had an 540 rebuilt after 300 hours on new ECI cylinders and we replaced all the exhaust valves due to wear.
Wow, what brought about the rebuild? Prop strike? Disuse? and did you need to replace the valve guide?

What vintage were your cylinders? My Mattituck was built ~2007.
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  #12  
Old 05-12-2015, 03:20 AM
rwtalbot rwtalbot is offline
 
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Originally Posted by 60av8tor View Post
Out of curiosity, did you have any hint of the valve wear during engine operation?
None whatsoever. Engine performed fine, comps all 78/80 or better.
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  #13  
Old 05-12-2015, 03:47 AM
kiwipete kiwipete is offline
 
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Prop strike inspection. Nil damage. Engine was 3 years since OH. (Late 2010) So after replacing the valves, cam and followers, bearings plus a couple of gears it was signed off as 0SMOH.
Not sure if the guides were worn. I'd have to look in the logs.
Was about $15,000 cheaper than buying a new engine.
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  #14  
Old 05-12-2015, 07:18 AM
Vansrv7arob Vansrv7arob is offline
 
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Originally Posted by BillL View Post
Heat is also an unseen factor here, as we would not know the temperature at the guide. So, the root cause could be something as obscure as low lube flow to the rocker box resulting in higher temps and lower lubrication.

Or something less obscure......

This is what I was worried about when I inspected my new ECI power assemblies delivered back in Feb.

Titan engine cylinder assembly - unboxing no audio: http://youtu.be/-6yreZzL3bw

I was told I was over thinking it.... Just bang it on, basic back ground in thermodynamics and fluid mechanics made me think ok yep not going to be optimal but no one else seamed to care or look closely enough at the situation. Basic research found similar prob seen with Porche air cooled enginges with ****ty finishing on inter valve cooling fin Flashing.

Perhaps hardened guides = more stem vs guide wear on ECIs Vs Lycomings with poor finishing? My best gueess....

Definitely read Bills report third link below...

Richard you've just conviced me my Eci cylinders are going to get a file job, i was a bit dissapointed when I saw ECIs sloppy finishing in this area area... There is an entire air passage missing/blanked off that the 2300 HR lycoming cylinders that I pulled off which had no operational valve issues.

It would be interesting to measure them up and see how much wear they have.

https://groups.yahoo.com/neo/groups/...messages/17408

http://showcase.netins.net/web/gregs...20problems.htm

http://showcase.netins.net/web/gregs...ing%20memo.pdf
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Last edited by Vansrv7arob : 05-12-2015 at 07:22 AM.
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  #15  
Old 05-12-2015, 07:10 PM
rwtalbot rwtalbot is offline
 
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Quote:
Originally Posted by Vansrv7arob View Post
Perhaps hardened guides = more stem vs guide wear on ECIs Vs Lycomings with poor finishing? My best gueess....

Definitely read Bills report third link below...
Very interesting. Those articles definitely point to high EGTs, inadequate cooling and poor cylinder finishing as the likely root cause. I can't really say that these cylinders have got overly hot.

I found another series of articles here that discuss the lack of oil cooling to the valves and valve stems in Lycoming Engines. Lycoming has provided additional oil cooling in the TIO-540-AF1B to resolve warranty issues with valve guide and valve stem wear.

There is an interesting observation made that valve distress and camshaft failure are likely to be closely linked. I'm not sure I buy that as it tends to be infrequently flown aircraft with cam failures. However, it does make me wonder why none of the experimental engine builders have increased oil flow to the rocker boxes?

http://egaa.home.mindspring.com/engine1.htm
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  #16  
Old 05-12-2015, 10:29 PM
Vansrv7arob Vansrv7arob is offline
 
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So what is the solution Richard? Find some one to manufacture non sodium filled exhaust valves, modified high flow plungers or fit Mooney cylinders?

It would be great if one of the experimental cylinder manufacturers finally sorted this problem for us.

As I see it the only practical thing we can do is try and optimise the air cooling by removing airflow obstructing intervalve flashing material that should not be there in the first place?
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  #17  
Old 05-13-2015, 03:32 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by rwtalbot View Post
However, it does make me wonder why none of the experimental engine builders have increased oil flow to the rocker boxes?
Some do. I was recently shown a custom 540 with rocker box fittings to connect an external oil supply. Also had oversize drainback lines. The system keeps the rocker boxes about half full.
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  #18  
Old 05-13-2015, 04:50 AM
rwtalbot rwtalbot is offline
 
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An extension to Marvel and Scott's work seems to point to an effective way to improve oil supply to the right side cylinders. Simply crank up the oil pressure as per the late model 172 and 206.

http://egaa.home.mindspring.com/new.htm

My question is how far one can go without risking rupturing the oil cooler, unseating the oil pressure bypass or other damage?

Anyway this work certainly seems to debunk the old myth that oil pressure in the cruise is not particularly important.
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Last edited by rwtalbot : 05-13-2015 at 05:10 AM. Reason: typos
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  #19  
Old 05-13-2015, 05:12 AM
rwtalbot rwtalbot is offline
 
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Originally Posted by DanH View Post
Some do. I was recently shown a custom 540 with rocker box fittings to connect an external oil supply.
Interesting, where were they taking the oil from?
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  #20  
Old 05-13-2015, 12:17 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by rwtalbot View Post
Interesting, where were they taking the oil from?
An accessory case gallery, IIRC. Sorry, no photos.
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