Glazed Cylinder Borescope Images

[TheAv8r]

Currently breaking in a freshly overhauled engine on my Mooney, I’m about 17 hours in with nickel cylinders and it’s still churning through oil indicating the rings haven’t sat yet. I borescoped the cylinders and saw oil pooling still with a healthy and strong crosshatch on the sides reinforcing that notion. The engine has always been run at or above 75% power and CHTs kept cool but part out of curiosity and part paranoia, what do glazed cylinders look like on a borescope? I googled and couldn’t find any examples. Some say the crosshatch will disappear, others say it’ll be a very strong dark brown splotch but no pictures. 

[dzeleski]

4 minutes ago, TheAv8r said:

Currently breaking in a freshly overhauled engine on my Mooney, I’m about 17 hours in with nickel cylinders and it’s still churning through oil indicating the rings haven’t sat yet. I borescoped the cylinders and saw oil pooling still with a healthy and strong crosshatch on the sides reinforcing that notion. The engine has always been run at or above 75% power and CHTs kept cool but part out of curiosity and part paranoia, what do glazed cylinders look like on a borescope? I googled and couldn’t find any examples. Some say the crosshatch will disappear, others say it’ll be a very strong dark brown splotch but no pictures. 

It should be a orangey brownish varnish looking coating. Its generally very patchy and inconsistent. The intensity of that color can change a bit, it can be really faint.

Nickel should generally break in extremely quickly. https://resources.savvyaviation.com/wp-content/uploads/slides_airventure2021/2021-07-28 0830 F7 Cylinder Break-In Do it Right.pdf

What does the oil consumption look like? Some pooling can happen if the rings just happen to line up the right way. I would fly the airplane for a bit and borescope again.

Glazing is Glazing, you dont need photos from an airplane engine, Autos have the same problem:
https://www.texassaltwaterfishingmagazine.com/gear/boats/excessive-idle-speed-operation-cylinder-wall-glazing

[N201MKTurbo]

Whatever is happening in your cylinders, unless it is scoring the cylinders, there is no reason to do anything rash. Just keep flying it. Unless the oil consumption is causing an operational issue like plug fouling. 

If it never gets better, you may need to pull it, replace the rings and re-hone it.

[Shadrach]

1 hour ago, TheAv8r said:

Currently breaking in a freshly overhauled engine on my Mooney, I’m about 17 hours in with nickel cylinders and it’s still churning through oil indicating the rings haven’t sat yet. I borescoped the cylinders and saw oil pooling still with a healthy and strong crosshatch on the sides reinforcing that notion. The engine has always been run at or above 75% power and CHTs kept cool but part out of curiosity and part paranoia, what do glazed cylinders look like on a borescope? I googled and couldn’t find any examples. Some say the crosshatch will disappear, others say it’ll be a very strong dark brown splotch but no pictures. 

I hate to be negative, but if you haven’t been able to establish oil control in 17hrs, it’s not likely to get much better. I can’t speak to what the problem is, but what you describe is not normal for nickel carbide cylinder break-in.

[TheAv8r]

1 hour ago, Shadrach said:

I hate to be negative, but if you haven’t been able to establish oil control in 17hrs, it’s not likely to get much better. I can’t speak to what the problem is, but what you describe is not normal for nickel carbide cylinder break-in.

 

2 hours ago, N201MKTurbo said:

Whatever is happening in your cylinders, unless it is scoring the cylinders, there is no reason to do anything rash. Just keep flying it. Unless the oil consumption is causing an operational issue like plug fouling. 

If it never gets better, you may need to pull it, replace the rings and re-hone it.

Thanks gents, this is kind of my dilemma here - some are telling me, just fly it, get past 25 or 35 hours and monitor it, others are saying, these cylinders should break-in instantly and you should be seeing stabilized results by now so sure, I'm not going to stop flying it and operating at 75%+ power, but it's a little worrying.

The bottom plugs when I pulled them were oily. 

Every flight has been done at high power and we minimized ground time as best we could at a towered airport (were only #2 for takeoff). We only did 1 other ground-run to leak-check and ensure engine control operations for just a few minutes prior to the first taxi, so I don't see much potential for glazing. CHTs have been cool.

 

[N201MKTurbo]

4 minutes ago, TheAv8r said:

 

Thanks gents, this is kind of my dilemma here - some are telling me, just fly it, get past 25 or 35 hours and monitor it, others are saying, these cylinders should break-in instantly and you should be seeing stabilized results by now so sure, I'm not going to stop flying it and operating at 75%+ power, but it's a little worrying.

The bottom plugs when I pulled them were oily. 

Every flight has been done at high power and we minimized ground time as best we could at a towered airport (were only #2 for takeoff). We only did 1 other ground-run to leak-check and ensure engine control operations for just a few minutes prior to the first taxi, so I don't see much potential for glazing. CHTs have been cool.

 

Both sides are right. The cylinder shouldn't be doing that. And it might get better. Most likely it won't get worse. So, if it doesn't get better, you should talk to your rebuilder about warranty repair. 

What does the overhauler say about it?

 

[Shadrach]

7 minutes ago, TheAv8r said:

 

Thanks gents, this is kind of my dilemma here - some are telling me, just fly it, get past 25 or 35 hours and monitor it, others are saying, these cylinders should break-in instantly and you should be seeing stabilized results by now so sure, I'm not going to stop flying it and operating at 75%+ power, but it's a little worrying.

The bottom plugs when I pulled them were oily. 

Every flight has been done at high power and we minimized ground time as best we could at a towered airport (were only #2 for takeoff). We only did 1 other ground-run to leak-check and ensure engine control operations for just a few minutes prior to the first taxi, so I don't see much potential for glazing. CHTs have been cool.

 

When I broke in my steel cylinders, we did an oil change at just over 5hrs. Oil consumption was normal after that. Something weird is going on and it does not necessarily have anything to do with your break in procedure.

[TheAv8r]

50 minutes ago, N201MKTurbo said:

Both sides are right. The cylinder shouldn't be doing that. And it might get better. Most likely it won't get worse. So, if it doesn't get better, you should talk to your rebuilder about warranty repair. 

What does the overhauler say about it?

 

Thanks for your help Rich. I haven't reached out to them yet. I didn't want to create a problem if there wasn't one yet, and their instructions said to contact them at the 60hr mark if not happy with oil consumption. Plus, the oil consumption has been a bit hard to track because of the short 10hr period and the oil from the oil change filling the filter. I'm still trying to get a feel for it.

Just curious, if the consumption stabilizes, but the plugs remain oily - I assume still a reason for concern? Oil in the plugs indicates blow-by/lack of ring seating IMO which could still happen in the next 10, 15, 20 hours.

[EricJ]

24 minutes ago, TheAv8r said:

Thanks for your help Rich. I haven't reached out to them yet. I didn't want to create a problem if there wasn't one yet, and their instructions said to contact them at the 60hr mark if not happy with oil consumption.

That's another hint that a good thing to do is just run it and see what it does.   If it is doing something stupid at the 60 hour mark, then contact them as instructed.

When I bought my airplane my engine only had forty hours on it since an IRAN which included rehoning the cylinders, new rings, etc.    I don't think a good break-in was followed because oil consumption was completely inconsistent, and could go from 1qt/8hours to 1qt/1.5hrs and back and you never knew what it was going to do.   The rebuilder and the local Lycoming rep both said to just keep running it.    It did eventually calm down, but it took quite a while.   I didn't do anything special, it just settled down on its own.   I've put about 850 hours on it since then and it's been very consistent for a long time.

[N201MKTurbo]

1 hour ago, TheAv8r said:

Thanks for your help Rich. I haven't reached out to them yet. I didn't want to create a problem if there wasn't one yet, and their instructions said to contact them at the 60hr mark if not happy with oil consumption. Plus, the oil consumption has been a bit hard to track because of the short 10hr period and the oil from the oil change filling the filter. I'm still trying to get a feel for it.

Just curious, if the consumption stabilizes, but the plugs remain oily - I assume still a reason for concern? Oil in the plugs indicates blow-by/lack of ring seating IMO which could still happen in the next 10, 15, 20 hours.

Like Erik says, Just fly it to 60 hours and if it isn't the way you like it, get the overhauler to fix it.

[47U]

4 hours ago, TheAv8r said:

The bottom plugs when I pulled them were oily. 

Oily to the point of a fouled plug?  If it’s just wet but firing, I would continue to monitor.  And, by this stage in your break-in procedure, you are  alternating power settings every so often?  Once you get past your first oil change, get a handle on tracking that oil consumption.  It might be a good idea to review your break-in procedures.

[201Steve]

I ran into similar on a set of steel jugs. I was doing everything right for break in but the oil consumption was a sloppy mess on all jugs. What I learned was, not on cylinder overhauls are created equal. 
 

one could be using a very expensive vertical honing machine that actually machines the cylinder walls in a precise and consistent fashion. 
 

another could be using a dingleberry stone on the end of a drill, slapping new valve guides on it and calling it overhauled. 
 

we often say “recently overhauled” like it’s a specific value with predictable results. In reality it’s a spectrum ranging from made it way worse to made it way better. In my case cited, it was the made it worse variety. 
 

food for thought

[Shadrach]

2 hours ago, 201Steve said:

I ran into similar on a set of steel jugs. I was doing everything right for break in but the oil consumption was a sloppy mess on all jugs. What I learned was, not on cylinder overhauls are created equal. 
 

one could be using a very expensive vertical honing machine that actually machines the cylinder walls in a precise and consistent fashion. 
 

another could be using a dingleberry stone on the end of a drill, slapping new valve guides on it and calling it overhauled. 
 

we often say “recently overhauled” like it’s a specific value with predictable results. In reality it’s a spectrum ranging from made it way worse to made it way better. In my case cited, it was the made it worse variety. 
 

food for thought

I would never call it overhauled but years ago we replaced a cylinder on a Continental 0200 with a serviceable steel cylinder and new rings. We used a dingleberry hone on a hand drill and had no problems establishing oil control nor problems with oily plugs. Is a dingleberry as precise as a honing machine? Absolutely not.  Is it possible to get good results with a dingleberry hone? Absolutely.

[dzeleski]

I ran into break in issues after I had to replace a cylinder a couple of years ago. I followed the Lycoming break in procedure to a T. The shop that overhauled the cylinder told me to run it harder for a few hours so I ran it WOT, ROP, at 3000 feet for around ~2 hours. This was during cooler months so it was easier to keep temperatures in check. That actually fixed the break in delay and the cylinder has been perfect since.

Run the thing harder, get the pressures up so those rings really get seated. The PDF I linked above from Mike also recommends running as close to 100% power as possible.

[Shadrach]

35 minutes ago, dzeleski said:

I ran into break in issues after I had to replace a cylinder a couple of years ago. I followed the Lycoming break in procedure to a T. The shop that overhauled the cylinder told me to run it harder for a few hours so I ran it WOT, ROP, at 3000 feet for around ~2 hours. This was during cooler months so it was easier to keep temperatures in check. That actually fixed the break in delay and the cylinder has been perfect since.

Run the thing harder, get the pressures up so those rings really get seated. The PDF I linked above from Mike also recommends running as close to 100% power as possible.

Thats a pretty reasonable strategy but perhaps challenging in the Texas summer. If it were me, I likely would not bother with setting at a specific power percentage and would run it as hard as possible using CHTs as my guide while varying RPM setting.

[TheAv8r]

1 hour ago, dzeleski said:

I ran into break in issues after I had to replace a cylinder a couple of years ago. I followed the Lycoming break in procedure to a T. The shop that overhauled the cylinder told me to run it harder for a few hours so I ran it WOT, ROP, at 3000 feet for around ~2 hours. This was during cooler months so it was easier to keep temperatures in check. That actually fixed the break in delay and the cylinder has been perfect since.

Run the thing harder, get the pressures up so those rings really get seated. The PDF I linked above from Mike also recommends running as close to 100% power as possible.

Yeah, I've done this once, kept everything firewalled for about 1hr20min on a flight up North at 2500ft. CHTs were nice and cool so the temperatures weren't causing any issues. I've also varied power, I've done a few 80-85% power runs. Nothing under 75% power (verified against the POH and my JPI, which I had previously dialed in against the POH). Probably worth doing a WOT again and seeing if it helps.

[201Steve]

4 hours ago, Shadrach said:

I would never call it overhauled but years ago we replaced a cylinder on a Continental 0200 with a serviceable steel cylinder and new rings. We used a dingleberry hone on a hand drill and had no problems establishing oil control nor problems with oily plugs. Is a dingleberry as precise as a honing machine? Absolutely not.  Is it possible to get good results with a dingleberry hone? Absolutely.

There’s lots of ways to get a desired result. No argument there. What you knowingly choose to do is fine. My contribution to the OPs problem is that I had terrible results from a designated overhaul that used a dingleberry on my cylinders and it worked out like absolute dog doo. As a laymen, My assumption was “it’s overhauled”. In my new understanding, I whole heartedly disagree with the method of “overhaul” and it turns out that’s simply a judgment of the AP signing off the work. Maybe helpful to the poster, maybe not. 
 

not an attack on your dingleberry, I would just not allow it, personally, after going through all the trouble of removing and repairing a cylinder. It would be done the most optimal way as possible mostly regardless of price. 

[MikeOH]

Words to live by, I suppose, "Not an attack on your dingleberry"

[201Steve]

2 minutes ago, MikeOH said:

Words to live by, I suppose, "Not an attack on your dingleberry"

I was hoping that would be appreciated. 

[Jsno]

the instructi0ns that came with my nickel cylinders says to idle at 12/1400 rpm for two minutes with a 15 minute cooling time period, for three times.  Then fly for 30-40 minutes high cruise power.  I did this on a previous engine that I overhauled and the temps came down rapidly.  Also oil consumption was good. It took about 5 more hours to fully stabilize.

Did you use break in oil? 

Also the nickel is extremely hard.  So hard they cannot be replated. I would question if they were the correct rings for nickel if it was not breaking in.  All of the wear is on the rings.

I would not use a hone on the cylinders.  I would just replace the rings and ensure that they are for nickel.   

[Shadrach]

8 minutes ago, Jsno said:

the instructi0ns that came with my nickel cylinders says to idle at 12/1400 rpm for two minutes with a 15 minute cooling time period, for three times.  Then fly for 30-40 minutes high cruise power.  I did this on a previous engine that I overhauled and the temps came down rapidly.  Also oil consumption was good. It took about 5 more hours to fully stabilize.

Did you use break in oil? 

Also the nickel is extremely hard.  So hard they cannot be replated. I would question if they were the correct rings for nickel if it was not breaking in.  All of the wear is on the rings.

I would not use a hone on the cylinders.  I would just replace the rings and ensure that they are for nickel.   

I also thought that perhaps there was an issue with the rings. it would not be the first time a shop mismatched rings/cylinders.

My break in was similar to yours but the ground run was only for a few minutes to verify oil pressure and that everything was oil tight. 

 

 

[Shadrach]

On 7/16/2024 at 11:25 AM, 201Steve said:

There’s lots of ways to get a desired result. No argument there. What you knowingly choose to do is fine. My contribution to the OPs problem is that I had terrible results from a designated overhaul that used a dingleberry on my cylinders and it worked out like absolute dog doo. As a laymen, My assumption was “it’s overhauled”. In my new understanding, I whole heartedly disagree with the method of “overhaul” and it turns out that’s simply a judgment of the AP signing off the work. Maybe helpful to the poster, maybe not. 
 

not an attack on your dingleberry, I would just not allow it, personally, after going through all the trouble of removing and repairing a cylinder. It would be done the most optimal way as possible mostly regardless of price. 

I have no dingleberry nor plans to procure one. This was not about price. It was about time. I arrived for flight training and the C-150 I was to use was diagnosed with a cylinder crack the day after I arrived.  Plane was back in service within a few days of discovering problem. The cylinder we replaced remained in service for several years and may still be in service to this day for all I know.  I think technique plays a bigger roll than method. It seems your guy got 3 out of 4 to establish oil control…
Using a purpose built boring machine removes the human variable and improves QC. 

[TheAv8r]

1 minute ago, Jsno said:

the instructi0ns that came with my nickel cylinders says to idle at 12/1400 rpm for two minutes with a 15 minute cooling time period, for three times.  Then fly for 30-40 minutes high cruise power.  I did this on a previous engine that I overhauled and the temps came down rapidly.  Also oil consumption was good. It took about 5 more hours to fully stabilize.

Did you use break in oil? 

Also the nickel is extremely hard.  So hard they cannot be replated. I would question if they were the correct rings for nickel if it was not breaking in.  All of the wear is on the rings.

I would not use a hone on the cylinders.  I would just replace the rings and ensure that they are for nickel.   

Those are the run-in instructions, which the engine shop did prior to sending me the engine. 

Yep, using straight-weight mineral oil, Aeroshell 100. 

The engine shop is a very well known one so I'd hesitate to think they put the wrong piston rings on, but I do recall seeing something in ECI's notes on that very topic so something to check... 

[Jsno]

16 hours ago, TheAv8r said:

Those are the run-in instructions, which the engine shop did prior to sending me the engine. 

Yep, using straight-weight mineral oil, Aeroshell 100. 

The engine shop is a very well known one so I'd hesitate to think they put the wrong piston rings on, but I do recall seeing something in ECI's notes on that very topic so something to check... 

Mistakes can be made at even the best shops.  Human factors.

[PT20J]

There is a procedure for re-honing nickel cylinders

https://continental.aero/service-bulletins/ECi/92-9-6.pdf