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Cylinder Scoring

jump4way

Well Known Member
I'm looking for a little help on something. I have an ECI IO-360 parallel valve engine with 44 hours on it now. I've been breaking the engine in using the oil and oil change schedule recommended by ECI (Phillips 20/50 XC). I've been following their break in procedure running the engine between 65% and 75% power respecting CHTs. I've tried my best to keep them at or below 400. I haven't always been successful, the highest CHT I have seen is 445 for less than 30 seconds.

I'm 44 hours in now and the CHTs seem to have dropped a bit but oil usage is still 1 qt every 2-3 hours. I decided to pull the spark plugs and take a look inside to see if I could find any cause for the oil usage. What I found was vertical scoring on all of the cylinders but cylinder 2 was the worst. Below is what I found but I'm not sure of the cause.

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I also noticed some black specks of material in the cylinder walls. I'm not sure if it's ring delimitation, broken rings, carbon buildup, or anything else.

A9f9MOm.png


I ran a compression check following the horoscope pictures and I found that cylinder 2 was 70/80. The other 3 cylinders were 78/80. On each of the cylinders, I could hear air through the breather tube but on number 2 it was much more noticeable.

These are ECI cerminil cylinders from a new engine build circa 2013.

Any ideas? Does this warrant pulling a cylinder and getting it to a cylinder shop?

For comparison, below are the pics of the other cylinders.

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Can't help you with what to do on your engine, but as another data point -

Titan/ECI O-360, circa 2011, also Cerminil cylinders and with only two hours of test stand time - had significant scoring on one cylinder and some on two others. This was discovered during teardown on the engine at Penn-Yan (the engine had been stored for about 6 years).

The only guess was that there had been contaminants in the oil or the intake system at the assembler/test stand.

The engine was completely overhauled and the barrels were ring finished. The cam and lifters were replaced, but this was due to corrosion from sitting for so long.
 
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The first linked pic cylinder is glazed and that is why it is burning oil. The scoring marks are also a bit more agressive than light scoring. That cylinder should be honed and re-ringed. You will n ed to repeat break in once that is done
 
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Thanks Katanapilot. My engine seems to have a similar history to yours. Hopefully this doesn't require a complete overhaul though.

I don't know if they line up with the wrist pin or not but they do seem to go the full length of the throw of piston. If they were from the wrist pin, I think they would stop short of the top of the piston travel would they not?

For the cylinder glazing, there is oil inside the cylinder that is pushed up and down from the rings. I'm not certain but they thought I had while I was taking these pics was the brownish areas you see are fresh oil still liquid, not glazed on to the cylinder walls. The brown areas would move as the piston and rings traveled up and down If I remember correctly. Is this what leads you to believe its glazing or is it something other than the coloration?
 
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The glazing is coked oil in the cross hatch valleys and often occurs from getting temps too high during break in.. It is usually medium to dark brown. It is hard to tell from pictures, but rhis looks like glazing. The fact you ate burning oil supports that. If you can see shinny metal like the other pics after moving the piston, it is not glazing. Pooling oil in the cylinder and wet oily plugs are classic symptom of glazing.

1 quart in2 hours is a lot and is a sign that something is wrong, for a new engine, and unless the scoring is deep it is not likely the cause. Glazing could consume that much
 
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While the scoring on #2 looks bad, it may not be the oil consumption issue. What level do you maintain in the sump? Is it calibrated? What is your average flight time per flight? The engine will use a little oil when cold than hot, so there is an actual reduction with time from an ambient temp start.

My new YIO 360 180hp has some of the same light scoring, which disturbs me, but has not presented any function issue like temps, metal, or oil consumption. It has 50 hrs now, and the oil analysis and filter was very good with 35 hrs on the oil.

While it still may be necessary to remove that jug, I would suggest you make a couple of flights at 2 hours, and allow the oil to drop to 6 qts on the stick to see if it stabilizes. Also suggest 24-2500 RPM for the cruise.

Also, it would be helpful to know where those two scuff marks are relative to engine rotation direction. Like top, bottom, or side of the bore?
 
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While the scoring on #2 looks bad, it may not be the oil consumption issue. What level do you maintain in the sump? Is it calibrated? What is your average flight time per flight? The engine will use a little oil when cold than hot, so there is an actual reduction with time from an ambient temp start.

My new YIO 360 180hp has some of the same light scoring, which disturbs me, but has not presented any function issue like temps, metal, or oil consumption. It has 50 hrs now, and the oil analysis and filter was very good with 35 hrs on the oil.

While it still may be necessary to remove that jug, I would suggest you make a couple of flights at 2 hours, and allow the oil to drop to 6 qts on the stick to see if it stabilizes. Also suggest 24-2500 RPM for the cr.uise.

Also, it would be helpful to know where those two scuff marks are relative to engine rotation direction. Like top, bottom, or side of the bore?

Ive been running the Oil at 6 quarts. I've let it drop down to 5 before I added more just to see if it would stabilize somewhere in there. I'm in Arizona so OAT has been on the high side. My average flight time is on the order of an hour. Minimum has been 30 minutes and maximum of 2.5 hours. I did calibrate my dip stick and it actually reads accurately. I've been running at 2500 rpm unless I was cruising higher in an attempt to keep it cool. In that case, I needed to up the rpm to get the percent power up.

I have an email out with the photos to ECI to see what the rep comes up with. I'll report back if I get any information.

Any ideas what the debris is you see in the cylinders?
 
The glazing is coked oil in the cross hatch valleys and often occurs from getting temps too high during break in.. It is usually medium to dark brown. It is hard to tell from pictures, but rhis looks like glazing. The fact you ate burning oil supports that. If you can see shinny metal like the other pics after moving the piston, it is not glazing. Pooling oil in the cylinder and wet oily plugs are classic symptom of glazing.

1 quart in2 hours is a lot and is a sign that something is wrong, for a new engine, and unless the scoring is deep it is not likely the cause. Glazing could consume that much

I'll put the boroscope back in and see if I can get a better feeling of the location of the scoring and try to confirm whether or not I have glazing.

Thanks for the feedback.
 
cooling baffles!

While you are puzzling over the engine, I think you should focus some attention on why your cylinders got so hot. I immediately suspect you have baffle leaks that you are not aware of. Have you closed off the tunnels in the upper cowl inlet diffuser pieces? Have you made sure that the rather complicated area transitioning from seals on those diffuser pieces to the seals over the nose area of the engine doesn't have some overlooked holes?

You should not be seeing temps anything like that.
 
While you are puzzling over the engine, I think you should focus some attention on why your cylinders got so hot. I immediately suspect you have baffle leaks that you are not aware of. Have you closed off the tunnels in the upper cowl inlet diffuser pieces? Have you made sure that the rather complicated area transitioning from seals on those diffuser pieces to the seals over the nose area of the engine doesn't have some overlooked holes?

You should not be seeing temps anything like that.

I've been looking at the baffles. The wear pattern on the upper cowling seems to show a decent wear in pattern with the exception of one of the upper cowl diffuser pieces. I'll take a look at that and see if I can figure out a way to get that sealed better also.

I think part of my issue has been fuel related. What should I be seeing for fuel flow at say 75% power on a parallel valve IO-360? The data plate says 188HP so using the common math of multiplying the HP by .1 would give me a fuel flow of 14.1 at 75%. I'm seeing 13 with an AFR of 12.0. If I dial up the fuel on the SDS, I can drop the temps in cruise to around 365 - 370 with high Arizona ambient temps but I have to be at cruise speed. If I'm climbing, those temps are going to go up pretty quick.
 
Ive been running the Oil at 6 quarts. I've let it drop down to 5 before I added more just to see if it would stabilize somewhere in there. I'm in Arizona so OAT has been on the high side. My average flight time is on the order of an hour. Minimum has been 30 minutes and maximum of 2.5 hours. I did calibrate my dip stick and it actually reads accurately. I've been running at 2500 rpm unless I was cruising higher in an attempt to keep it cool. In that case, I needed to up the rpm to get the percent power up.

I have an email out with the photos to ECI to see what the rep comes up with. I'll report back if I get any information.

Any ideas what the debris is you see in the cylinders?

Not sure, it could be lead pearls, with mean high combustion temps, or carbon specks, but you might check the piston crown in that specific area to see if there was debris ingestion that deformed the top land. Doubtful, but lots of things can happen. I've seen FOD on piston and head that did not result in scoring. That bore camera can be a bit deceiving for color and reflections.

Sorry for more questions than answers, but related to Steve Smiths post for high CHT causes, what ignition system do you have? SDS??

Good move to ask ECI, as they know these bores the best. Scuffing can result from many possible details. Bottom line is it is a combination of poor lubrication and high contact stresses that heats a small area of contact. The possible failure tree expands from there. In order to see the effects on the spark plugs (oil) one would need to be lean on approach and roll out, minimize taxi . . . shut down, then pull the plugs to see if there is more oil on one cylinder than others. Even then it might not be definitive.
 
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Not sure, it could be lead pearls, with mean high combustion temps, or carbon specks, but you might check the piston crown in that specific area to see if there was debris ingestion that deformed the top land. Doubtful, but lots of things can happen. I've seen FOD on piston and head that did not result in scoring. That bore camera can be a bit deceiving for color and reflections.

Sorry for more questions than answers, but related to Steve Smiths post for high CHT causes, what ignition system do you have? SDS??

Good move to ask ECI, as they know these bores the best. Scuffing can result from many possible details. Bottom line is it is a combination of poor lubrication and high contact stresses that heats a small area of contact. The possible failure tree expands from there. In order to see the effects on the spark plugs (oil) one would need to be lean on approach and roll out, minimize taxi . . . shut down, then pull the plugs to see if there is more oil on one cylinder than others. Even then it might not be definitive.

Yeah, I'm running the SDS system for fuel and ignition (which I really love by the way). The piston heads were relatively clean from what I remember but ill do another deep dive in that cylinder today and see what I can find. One thing I learned with the boroscope is that it can be frightening when you don't really know what you're looking at.
 
I'll put the boroscope back in and see if I can get a better feeling of the location of the scoring and try to confirm whether or not I have glazing.

Thanks for the feedback.

I had glazing on two of my cylinders and I was able to identify it just by looking in the spark plug holes. That yellowish, brown color on the walls is easy to see when using a flashlight. Its pretty easy, if the walls are shinny metal, its not glazed. If they have an opaque type of light, medium brown coloring, they are glazed. It would LOOK like they had a coating of dirty oil on them, but that's not what it is. You will typically find the coverage is not 100%. Some parts of the wall will be brown and others will have shiny metal. Your pic is pretty much a good example of what glazing looks like.

In my case, the CHTs got to 440 for about 15 seconds during the first couple of hours and that was all it took to glaze them. The glazed cylinders also has pooled oil at the piston/wall intersection (at low point) and wet, oily plugs. A quick hone and new rings fixed it right up. However, the alloy in your cylinders will require a special honing process.

Larry
 
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You need to pull the cylinders and get them rehoned with new rings. It doesn't matter how many hours are on the engine, if the cylinders get glazed it is what it is. I have a couple of different hones I used for this task, depending on how scored the cylinders are. In my experience high CHT's results from fueling issues and not necessarily cooling issues. In some cases excessive deposits in the combustion chamber can cause runaway CHTs, due to preignition. In this case it sounds like you're running too lean and you should be closer to 16gph based on your HP.
 
Update

Just a quick update. I received a reply back from continental regarding my cylinders. They said cylinder two needed to be pulled and replaced do to the scoring and the lower compression. I have a warranty replacement on the way. Once I receive that, I'll take some pictures of the cylinder to determine exactly what area was scored and hopefully shed a little light on what the cause is.

I was hoping for some information about what the potential cause is for issue but at this point, I've gotten nothing from them. They don't seem concerned about the other cylinders due to the compression indicating 78/80.
 
You need to pull the cylinders and get them rehoned with new rings. It doesn't matter how many hours are on the engine, if the cylinders get glazed it is what it is. I have a couple of different hones I used for this task, depending on how scored the cylinders are. In my experience high CHT's results from fueling issues and not necessarily cooling issues. In some cases excessive deposits in the combustion chamber can cause runaway CHTs, due to preignition. In this case it sounds like you're running too lean and you should be closer to 16gph based on your HP.

16 gph at 75% power? I don't think so.
 
I've been looking at the baffles. The wear pattern on the upper cowling seems to show a decent wear in pattern with the exception of one of the upper cowl diffuser pieces. I'll take a look at that and see if I can figure out a way to get that sealed better also.

I think part of my issue has been fuel related. What should I be seeing for fuel flow at say 75% power on a parallel valve IO-360? The data plate says 188HP so using the common math of multiplying the HP by .1 would give me a fuel flow of 14.1 at 75%. I'm seeing 13 with an AFR of 12.0. If I dial up the fuel on the SDS, I can drop the temps in cruise to around 365 - 370 with high Arizona ambient temps but I have to be at cruise speed. If I'm climbing, those temps are going to go up pretty quick.

There are way too many variables to judge mixture from fuel flow. instead, determine degrees EGT in relation to peak.

Start reading at post #35:

http://www.vansairforce.com/community/showthread.php?t=86179&highlight=peak&page=4
 
Part of the original question....

scoring.

I have a question about wrist-pin scoring on cylinder walls. Can a small amount of light scoring from wrist pins be expected and normal? Or is it always a sign of an issue?
 
scoring.

I have a question about wrist-pin scoring on cylinder walls. Can a small amount of light scoring from wrist pins be expected and normal? Or is it always a sign of an issue?

One can see "scoring" that is only a few dozen millionths of an inch deep, so only looking at images, I believe it is difficult to make a judgement. Every engine I can recall (auto, airplane) looking at had some amount of visual, vertical scuff/scoring marks. Think of chunks of carbon/lead busting off and getting scraped up and down in the tiny gap below the piston top but above the ring.
 
One can see "scoring" that is only a few dozen millionths of an inch deep, so only looking at images, I believe it is difficult to make a judgement. Every engine I can recall (auto, airplane) looking at had some amount of visual, vertical scuff/scoring marks. Think of chunks of carbon/lead busting off and getting scraped up and down in the tiny gap below the piston top but above the ring.

I agree. Although your description doesn't specifically address wrist pin scuffing. But it is easy to imagine little bits of stuff getting lodged in the pocket at the wrist pin ends and scuffing along a little bit.

The motivation for the question is that my 500 hr engine with great compression, very cool temps, very low oil consumption (12--15 hrs/qt) got borescoped at 450 hrs. The borescope can really make mountains out of mole hills -- which is to say you can clearly see things that are very insignificant. And yes, all four of my cylinders showed some sign of very minor scuffing by the wrist pin ends. Absent any other indication of a problem, my plan is to do nothing. I bet it is normal, but not many engines get borescoped.

But I'm curious what others think.
 
Many years ago, the Lyc O-360 in our Archer had a wrist pin wear issue on one cylinder. When we removed the primary oil screen for inspection during the Annual, we observed dozens of very small, nail clipping-like aluminum shavings trapped in the coarse finger screen -- as I recall the oil filter media was pretty clean. Somewhat surprisingly to us, the subsequent cylinder inspection showed just a touch of vertical scuffing/discoloration on the cylinder wall where the disintegrating piston pin plug traversed. Back in those good old days, we lightly honed the 1,200-hour cylinder, replaced the piston pin plug, installed new rings, and flushed out the oil system as best we could. That engine then continued to purr right up to TBO. YMMV
 
I agree. Although your description doesn't specifically address wrist pin scuffing. But it is easy to imagine little bits of stuff getting lodged in the pocket at the wrist pin ends and scuffing along a little bit.

The motivation for the question is that my 500 hr engine with great compression, very cool temps, very low oil consumption (12--15 hrs/qt) got borescoped at 450 hrs. The borescope can really make mountains out of mole hills -- which is to say you can clearly see things that are very insignificant. And yes, all four of my cylinders showed some sign of very minor scuffing by the wrist pin ends. Absent any other indication of a problem, my plan is to do nothing. I bet it is normal, but not many engines get borescoped.

But I'm curious what others think.

Under normal circumstances, you can't get meaningfull scoring from the wrist pins until the pin plugs are fully disintegrated, as they are softer than the steel wall. My engine eat up several pin plugs and had NO detectable scoring or even significant scuffing on the cyl wall. You can expect a visible mark on the cyl wall where the pin plug rides up and down, but that doesn't mean it is scored or scuffed.

Larry
 
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Just a quick follow up on this thread.

After pulling the cylinder off and getting a look inside, the scoring is not near as noticeable as it is with the boroscope. You cannot feel it with touch either. There are a couple of small areas that appear to have glazing. The scuff marks do not line up with the wrist pin, they were on the adjacent portion of the cylinder.

There were some scuff marks on the piston that correlate with the cylinder wall scuff marks. Im not certain of the cause. It will be interesting to see what ECI says when they receive the cylinder.
 
I agree. Although your description doesn't specifically address wrist pin scuffing. But it is easy to imagine little bits of stuff getting lodged in the pocket at the wrist pin ends and scuffing along a little bit.

The motivation for the question is that my 500 hr engine with great compression, very cool temps, very low oil consumption (12--15 hrs/qt) got borescoped at 450 hrs. The borescope can really make mountains out of mole hills -- which is to say you can clearly see things that are very insignificant. And yes, all four of my cylinders showed some sign of very minor scuffing by the wrist pin ends. Absent any other indication of a problem, my plan is to do nothing. I bet it is normal, but not many engines get borescoped.

But I'm curious what others think.

Agree Steve.
 
Just a quick follow up on this thread.

After pulling the cylinder off and getting a look inside, the scoring is not near as noticeable as it is with the boroscope. You cannot feel it with touch either. There are a couple of small areas that appear to have glazing. The scuff marks do not line up with the wrist pin, they were on the adjacent portion of the cylinder.

There were some scuff marks on the piston that correlate with the cylinder wall scuff marks. Im not certain of the cause. It will be interesting to see what ECI says when they receive the cylinder.

Let us know, hopefully it will get returned "improved".
 
Dealing with a similar issue on a friend's engine, curious what the resolution was here?
 
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