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ECI Valve Wear - 350 hours

rwtalbot

Well Known Member
I have four ECI exhaust valves that came out of a set of ECI Titan group A cylinders at 350 hours. Since the cylinders had to be destroyed we took out the valves and threw then in a box. I have recently been working on another engine project and just for kicks decided to run a micrometer over them.

I discovered that all four ECI valves were worn beyond limits. They all have 2-3 thou steps in them. I would not have expected that after 350 hours. In contrast the six genuine Lycoming valves I have out of another engine (2,200 TTIS) are worn less. Four out of the six show 1-1.5 thou wear, the others are at 2 thou. Anyone got any ideas why?

When we took these cylinders off they looked fantastic. compressions all 78/80, no deposits, pistons in great condition, nothing looked burnt. Now I am wondering if that really was the case.

The ECI engine was run with PMAGs and regularly LOP for 300 hours or so. The Lycoming had mags and was run LOP for the last 300 hours too.

The pictures below show the ECI valve on the left and Lycoming on the right for comparison. The Lycoming has had some cleaning, particularly deposits removed. The ECI has not.

vfxydu.jpg


Close-up of the base of the valves.

28is4md.jpg


25gte1d.jpg


All four ECI valves from the engine from comparison, least wear from left to right. Note pink ink is the engineer's markings to reject the valve.

23lfgw4.jpg
 
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Mr too!

I too would not have expected these to mice out to this wear pattern at only 300 hours. Most of these valve come from the same O.E.M., but not always, there are some other prices that are in the market too. I would drop this back to E.C.I. and let them know what you found. They may wish to look at the guides and the metallurgy to see if they are an off batch. The two you show in the second row show that on the E.C.I. valve face the seat is contacting the face just right, with the small relief at the top of the face and the wider band at the bottom. The one on the right is seated a little low in the seat as the contact area is hi on the valve face. If it were mine I would not regrind the seat though. It still has a lot of contact area and you will not be asking it to turn 9,000 R.P.M.s at 10.5:1 on a hi alk. mix fuel. The guys at E.C.I are good people and they like to hear about this kid of stuff. They have a nice Lab that is set up to check for all kind of good and bad batches of parts. They do get some bad supplies too, just as we all do.
Hope this helps. Yours as always. R.E.A. III #80888
 
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From my passed experience that would be a total waist of your time, ECI does not care.
I too would not have expected these to mice out to this wear pattern at only 300 hours. Most of these valve come from the same O.E.M., but not always, there are some other prices that are in the market too. I would drop this back to E.C.I. and let them know what you found. They may wish to look at the guides and the metallurgy to see if they are an off batch. The two you show in the second row show that on the E.C.I. valve face the seat is contacting the face just right, with the small relief at the top of the face and the wider band at the bottom. The one on the right is seated a little low in the seat as the contact area is hi on the valve face. If it were mine I would not regrind the seat though. It still has a lot of contact area and you will not be asking it to turn 9,000 R.P.M.s at 10.5:1 on a hi alk. mix fuel. The guys at E.C.I are good people and they like to hear about this kid of stuff. They have a nice Lab that is set up to check for all kind of good and bad batches of parts. They do get some bad supplies too, just as we all do.
Hope this helps. Yours as always. R.E.A. III #80888
 
Just speculating, but is it possible that the wear was due to poor rocker arm geometry putting excessive side load on the valve stems?

Skylor
 
Just speculating, but is it possible that the wear was due to poor rocker arm geometry putting excessive side load on the valve stems?

Quite possible, the cylinders were installed on a new Mattituck engine, so I would like to think that wasn't the problem.

I have heard that the ECI valve guides are harder than the Lycoming units. Perhaps that causes additional wear to the stems. I just don't know. I was hoping someone might have seen this before.
 
How did you get an accurate measurement without cleaning the valves? Is it possible that the deposits are affecting the measurements that you took?
 
Academically, it would point to lubrication, then valve guide material compatibility with the stems. 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.

But that is just theory, and a place to start gathering (expensively obtained) data.
 
How did you get an accurate measurement without cleaning the valves? Is it possible that the deposits are affecting the measurements that you took?

I am guessing the engineer working on them wasn't going to waste time cleaning them unless they initially measured good. Its possible they will measure up worse after cleaning, which still doesn't make me feel any happier.
 
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.

Peter
 
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.
 
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.
 
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/lycoming/conversations/messages/17408

http://showcase.netins.net/web/gregscheetah/Lycoming cylinder problems.htm

http://showcase.netins.net/web/gregscheetah/Misc Documents_files/Bill's lycoming memo.pdf
 
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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
 
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?
 
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.
 
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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Valve & Guide wear

I feel this is worth mentioning again. The Lycoming exhaust valve rocker arm bushing has a groove (annulus) around the outside perimeter to get extra oil to the valve where it exits the guide for cooling and lube. Not saying that it's the cause here but there are a couple ways to get this wrong. 1 way is to have correct bushings in the exhaust rockers but they get incorrectly installed on the intake valves and intake rockers get installed on the exhaust valves. Another wrong way is overhaul shop incorrectly installs intake bushings (no annulus) in all rocker arms and rockers get installed anyway. I've seen both scenarios several times and the first sign of trouble is valve issues around 400hrs. Before installing exhaust rocker arms slide them on a rocker shaft and blow some shop air in the hole in the pushrod socket and make sure air comes out the oil hole on opposite side.

Don B

RV 9 Rebuild in Progress
 
The guides should be taking most of any pressure wear. I once bought a seat of high end heads for a big block Chevy. I had to tear it down after about 100 miles and found oil build up on some of valves and the guides were quite worn. My best guess was that it was near miller time when my heads were built and the idiot didn't clean the abrasive out of the guides after reamiing or lapping. Working with the Engineers, we could not find any other reason.

I pulled the valves out of my rebuilt O-320 jugs to grease the guides. When cleaning them, they were filthy. Any abrasive material in there will wear the guide AND the valve

Larry
 
Lapping compound

The guides should be taking most of any pressure wear. I once bought a seat of high end heads for a big block Chevy. I had to tear it down after about 100 miles and found oil build up on some of valves and the guides were quite worn. My best guess was that it was near miller time when my heads were built and the idiot didn't clean the abrasive out of the guides after reamiing or lapping. Working with the Engineers, we could not find any other reason.

I pulled the valves out of my rebuilt O-320 jugs to grease the guides. When cleaning them, they were filthy. Any abrasive material in there will wear the guide AND the valve

Larry

That is a very common cause of valve guide failure after a head rebuild on automotive engines. Number one rule. Clean it. Clean it again then ten more times to be sure. The grinding compound is very abrasive.
Wouldn't surprise me to see the same on airplane engines.
 
ECi has been using the high chrome content exhaust valve guides for many years with excellent results. On certified engines the exhaust valve is required to be replaced at overhaul, even if the dimensions are the same as a new part. With the older exhaust valve guides we were seeing very little valve stem wear and a lot of valve guide wear at TBO, on our parts and on our competitor?s parts. This guide wear tends to decrease the valve seal at the seat, later in the cylinders life cycle.
In 2003, Lycoming mandated the use of high chrome alloy exhaust guides. ECi followed suit. This change improves and maintains valve stem to guide clearance over the life of the cylinder. This combination has less valve guide wear and a little more stem wear over the life of the two parts. This balancing of wear improves valve seal over the components life time. This is supported by the fact that the valve face to seat interface is still sealing properly and the cylinders and valves had normal compression test numbers, even though there was measured wear of the stem in the pictures.
 
This combination has less valve guide wear and a little more stem wear over the life of the two parts.

That's interesting. I'd be interested in the basis for 2 thou limits on the valve stem vs. 1 thou per 100 hours on the valve guide (according to Lycoming SB 388C). Is there something about the sodium filled stem which makes wear a problem?
 
ECi has been using the high chrome content exhaust valve guides for many years with excellent results. On certified engines the exhaust valve is required to be replaced at overhaul, even if the dimensions are the same as a new part. With the older exhaust valve guides we were seeing very little valve stem wear and a lot of valve guide wear at TBO, on our parts and on our competitor?s parts. This guide wear tends to decrease the valve seal at the seat, later in the cylinders life cycle.
In 2003, Lycoming mandated the use of high chrome alloy exhaust guides. ECi followed suit. This change improves and maintains valve stem to guide clearance over the life of the cylinder. This combination has less valve guide wear and a little more stem wear over the life of the two parts. This balancing of wear improves valve seal over the components life time. This is supported by the fact that the valve face to seat interface is still sealing properly and the cylinders and valves had normal compression test numbers, even though there was measured wear of the stem in the pictures.

So why the failure? :confused:
 
So why the failure? :confused:

What failure? The valves were working perfectly when they were removed with compressions in the high 70's.They have a good seat seal. They have a claimed 2-3 thousand step that I cannot see in the photos there is no valve guide measurement to compare clearance between the two parts. These valves were working properly and could have gone to service life if they had stayed in service.
The cylinders were removed from service and replaced by us to comply with a cylinder AD. 2009-26-12 about potential cracking. The old cylinders were required to be destroyed by us as part of the AD. This owner removed the valves and saved them and now is making observations comparisons about their wear, compared to the older design valve and guide combination.
 
What failure? The valves were working perfectly when they were removed with compressions in the high 70's.They have a good seat seal. They have a claimed 2-3 thousand step that I cannot see in the photos there is no valve guide measurement to compare clearance between the two parts. These valves were working properly and could have gone to service life if they had stayed in service.
The cylinders were removed from service and replaced by us to comply with a cylinder AD. 2009-26-12 about potential cracking. The old cylinders were required to be destroyed by us as part of the AD. This owner removed the valves and saved them and now is making observations comparisons about their wear, compared to the older design valve and guide combination.

I completely agree! This entire thread makes zero sense. What is the point? How do you "measure" valve stem wear and get an accurate indication of a .002"-.003" wear step with carbon and lead deposits still on the valve stems. I thought it was just me:D
 
Oh I think the original posting was valid. Parts wear and its good to ponder why and how. Then the thread slid into the ditch.
 
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