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Clogged oil suction screen--new engine...yikes!

Langt

Member
I have a Titan X-340, with less than 20 hours operation since first start last season. During its very first oil change today, I pulled the oil suction strainer. It appears to be about 50% clogged! How is that possible? I have not yet cut the paper spin-on filter open and I have not yet expelled the debris from the inside of the screen. The stuff extruded outside is only carbon like material. Based on my EMS, oil pressure has always been rock solid with no indication of any abnormality. Oil temperature has not been over 220F. CHT has rarely been over 400 F, only once to about 420 on #2. The break-in oil was Philips X/C 20W-50 with no additives.

Hopefully attached are two photos, one exterior, the other down the middle of the screen. Clearly, this is far from ideal, but I guess I'm wondering what happened to cause this and how serious it is.

Note: The cap may or may not be on the same end as when removed.
 

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Any chance this engine was rebuilt - but the finger screen never removed and cleaned?

Carl

It was bought as a new experimental engine directly from Continental. They say they perform a test run, which was evident based on light carbon in the exhaust, but otherwise no sign of prior use. Also new hoses and oil cooler.

I'll be looking at the particles and paper filter more tomorrow once I cut it open unless I'm too depressed.
 
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Looks like new engine gunk from assembly, such as excess sealant that has come free and some minor corrosion products that are result of storage. I'd change the oil at another 25 hours and expect to see a little material, but less.

More importantly, how does your filter look? If you have some debris, but less than a 1/4 teaspoon in total, you're within the guidelines of Lycoming's SB 480F, which is a recommended read for you.

If you don't already do so, I recommend doing oil analysis at each change - Blackstone Labs are who I use.
 
Insects that got in through the breather? Mud daubers or ants? With only 20 hours with lots of time sitting, who knows what crawled in there.
 
Thanks for the thoughts so far. A little more data and pictures. I cleaned out the strainer. Much of material adhered to strainer such that it needed to be scraped off, although there was also loose granular material inside, some of which could be rinsed out with 100LL. I poked the material out of the screen holes with 0.032 safety wire, which offered resistance until it poked through.

The granular material is somewhat gritty, but breaks down to dust when firmly pressed and rolled between fingers. It has no observable metallic character. Even the material in the 100LL had no sparkle and was not affected by magnetism. As can be seen in the picture, the material is actually amber to dark brown in color, not black and not silver. We looked at some of it (with help of Tony from Van's) under magnification. Some looked like little pieces of translucent amber, others were darker brown--you could imagine those particles to be almost anything, even the bug parts as was postulated, although no heads, legs, etc. All of the material removed from the strainer is either on the paper or in the cup (photos)

Upon opening the spin-on paper filter, I found VERY little of the material, though micro-particles would be hard to discern. In total, I would say the filter had a very small fraction (1 percent?) of the granules as was in the strainer. There were a very few TINY specks of metal there, smaller than crushed pepper, and no measurable volume.

So, with that, I'll inquire with Continental Tomorrow.
 

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Curious. Are you using X/C20w50, or 20W50 Type M for break in? For my engine overhaul, the builder and Continental both stated using only Mineral oil for break in, roughly about 50 hours.
 
Thanks for the thoughts so far. A little more data and pictures. I cleaned out the strainer. Much of material adhered to strainer such that it needed to be scraped off, although there was also loose granular material inside, some of which could be rinsed out with 100LL. I poked the material out of the screen holes with 0.032 safety wire, which offered resistance until it poked through.

The granular material is somewhat gritty, but breaks down to dust when firmly pressed and rolled between fingers. It has no observable metallic character. Even the material in the 100LL had no sparkle and was not affected by magnetism. As can be seen in the picture, the material is actually amber to dark brown in color, not black and not silver. We looked at some of it (with help of Tony from Van's) under magnification. Some looked like little pieces of translucent amber, others were darker brown--you could imagine those particles to be almost anything, even the bug parts as was postulated, although no heads, legs, etc. All of the material removed from the strainer is either on the paper or in the cup (photos)

Upon opening the spin-on paper filter, I found VERY little of the material, though micro-particles would be hard to discern. In total, I would say the filter had a very small fraction (1 percent?) of the granules as was in the strainer. There were a very few TINY specks of metal there, smaller than crushed pepper, and no measurable volume.

So, with that, I'll inquire with Continental Tomorrow.

Those are carbon chunks from oil burning and coking around the rings and lands. The engine will burn a good bit of oil in the first couple of hours and those carbon chunks are a byproduct. The fact that you have that many would seem to imply that you are still burning a good amount of oil. I would pull your plugs and look for glazed cylinders. Oil soaked plugs are another sign of glazing. If one or more are glazed, you will continue to burn oil at a high rate and that results in carbon chunks getting into the oil.

Larry
 
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Those are carbon chunks from oil burning and coking around the rings and lands. The engine will burn a good bit of oil in the first couple of hours and those carbon chunks are a byproduct. The fact that you have that many would seem to imply that you are still burning a good amount of oil. I would pull your plugs and look for glazed cylinders. Oil soaked plugs are another sign of glazing. If one or more are glazed, you will continue to burn oil at a high rate and that results in carbon chunks getting into the oil.

Larry

Your response has to be right, if for no other reason that its the worse possible outcome (i.e. requiring top end disassembly, honing and new rings).

I ordered a boroscope to take a good look. As for carbon, my exhaust started out oily soot, and is now just black soot. That part is about right for 14 hours tach time with nickel carbide cylinders. Oil use is high, but not remarkable for an engine that is 1/3 through break-in.
 
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Curious. Are you using X/C20w50, or 20W50 Type M for break in? For my engine overhaul, the builder and Continental both stated using only Mineral oil for break in, roughly about 50 hours.

I am using Philips X/C 20W-50 with no extra additives (that I added). This is mineral oil, but includes ashless dispersant.

All sources, all companies, say to use mineral oil. Fewer seem to care if its multi-grade mineral oil. None want wear inhibitors as in the lycoming additive or camguard. In general, and reading a bit between the lines, I think ashless disperant itself is not so much a problem as that often other additives are present as well that improve lubricity (i.e. shell W100+) or extreme pressure wear properties. So saying "straight, single grade, no additive mineral oil" just makes it easy.

Interestingly, Phillips X/C 20W-50 was exclusively recommended in the ECI "Engine Break-in Instructions and Oil Management" document written by ECI before Continental took them over. However, it is supposed to be changed at 10 hours (which I failed to meet) Presently, continental does not specifically recommend X/C and does not want ashless dispersants, but...

I did contact Continental. They said they have not seen this before, and thought perhaps it was some sort of contamination with rust preventative oil (if I added any), which I did not. I told them I had used X/C and they took no issue with that oil as a contributor.

I just spoke with Phillips. They seem especially interested and told me that the X/C is in fact an excellent break in oil (as noted on their web page) that is has nothing in it that could adversely affect break in, it has not been changed in any way adverse to break in since the ECI guidance was written, and that, as in the ECI document, the ashless dispersant they use is actually helpful during break in (it would tend to reduce the very deposits that I observed). They want more information, pictures, etc.

I did send a sample to blackstone for analysis. More on that when it comes.

So, for now, I think that leaves me with three possible causes:

1) A reaction with something that was in the crankcase
2) Inadequate break-in protocol (too much low power operation)
3) Too long before oil change.
 
So, for now, I think that leaves me with three possible causes:

1) A reaction with something that was in the crankcase
2) Inadequate break-in protocol (too much low power operation)
3) Too long before oil change.

You might want to consider the possibility of bad cylinder(s), similar to what I reported in my post here

I would not be surprised if the “new” ECI cylinders (Continental owned) were exactly the same as the “old” ones.

My understanding of nickel cylinders is that they break in very quickly - on the order of around 5-10 hours.
 
You might want to consider the possibility of bad cylinder(s), similar to what I reported in my post here

I would not be surprised if the “new” ECI cylinders (Continental owned) were exactly the same as the “old” ones.

My understanding of nickel cylinders is that they break in very quickly - on the order of around 5-10 hours.

Guess I was wrong before due to being an optimist. Worst outcome is NOT bad break in -- Its bad cylinders!

My engine was purchased in late 2018 from continental. How do I know if they are continental vs affected ECI cylinders, of if it makes any difference?
 
Your response has to be right, if for no other reason that its the worse possible outcome (i.e. requiring top end disassembly, honing and new rings).

I ordered a boroscope to take a good look. As for carbon, my exhaust started out oily soot, and is now just black soot. That part is about right for 14 hours tach time with nickel carbide cylinders. Oil use is high, but not remarkable for an engine that is 1/3 through break-in.

You don't need a borescope. Pull both plugs and look in at the cyl walls; a dim flashlight in opposite hole helps. Shinny silver = good, opaque tan colored coating = glazing. glazed cylinders will usually leave the plug wet with oil. carefull though, as often only portions of the wall are glazed, not the whole surface.

IMHO, oil consumption should be way down after 14 hours. If you are still burning a lot of oil, that further points to glazing. While some consder the full break in to be 50 hours, that doesn't mean oil consumption will be high for that long. 80-90% of the ring seating happens in the first 5 hours. After that, it is just polishing. Oil consumption should start dropping as soon as you start seeing the CHT's dropping and by 10 hours should be in the neighborhood of what you will see for the next 1000 hours. Chrome are a different animal. Nickel may take a bit longer, but not that much longer. Remember that most modern cylinders are nitrided / case hardened and I doubt they are any softer than the nickel stuff. Nickel's benefit is primarily corrosion resistance.

If you have black soot in the pipes, you are running too rich. Filthy rich makes sense in the first 5 hours to deal with the heat and to help flush out the metal being cut by ring seating, but after that you can lean back to best power.

Larry
 
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Just a follow up on the condition, since a lot of time has passed. The independent oil lab I used said the oil looked typical for break-in, but they didn't know what the dry sample material was. Apparently, they could not get it to dissolve, which they need to do to test it. In the end, I did not send samples to Philips (which I probably should have).

Flushing the crankcase with kerosene, I got out 3 more dime sized brown/black, brittle texture flakes. These became soft and sticky, and tan/brown overnight after exposure to air like the earlier material. I inspected cylinders and oil sump with the boroscope I had purchased. The cylinders looked good to me and to an A/P, IA friend (silver, not amber colored with no apparent glazing, cross hatch pattern still clear) However, my sump had areas where it looked like an adherent "material" of some sort had broken free (see photos).

My compressions were 80/80/75/80. I ran the engine for about an hour on the ground, and rechecked the screen (all clear). I filled it back up, this time with Shell W100 since it is now hot outside (mineral oil with Ashless dispersant, but no anti wear additive). Flew about 7 hours and rechecked the screen yesterday. Oil consumption is now pretty good --my level dropped maybe 1/8" after the 7 hours. Then I drained and re-inspected the strainer screen. Pretty much as I expected, there was some new material in the screen (see photos), but probably 5-10 percent as much this time. It all wiped off easily, whereas the original stuff had to be scraped off. Otherwise, it looked the like the same stuff.

I will fly about another 14 hours, and recheck.

I now think this was something in the crankcase from the factory.
 

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Any news, hopefully ok.

You must be psychic! I let it go a little longer than planned; but just changed oil yesterday 12/2/22, at about 42 hobbs hours, which is approximately 20 additional hobbs hours since the last sample I would say its very similar to what I got the last time after 7 hours, so the rate of accumulation is slowing down. The oil filter is currently being drained -- I'll cut it open this week.

Getting on into Winter and long down times, I would like to start it on Camguard. So, dealing with this "stuff" in my strainer, I'm wondering whether a newly introduced additive (Camguard) will cause more of the strainer clogging "material" to be liberated. (I probably worry too much)

Thanks for the concern!

Ted
 

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Good to hear it's not getting worse

I would get some input from the VAF participants who know a lot more than me about using Camguard (or any additives) before you know the status of break-in. If your engine is looking "directionally correct" don't add a new variable, yet. I don't recall but did you get an oil analysis? Although these cannot tell you exactly if you are at second base, they will let you know you are somewhere in the infield.
 
--- snip ---

Getting on into Winter and long down times, I would like to start it on Camguard. So, dealing with this "stuff" in my strainer, I'm wondering whether a newly introduced additive (Camguard) will cause more of the strainer clogging "material" to be liberated. (I probably worry too much)

Thanks for the concern!

Ted

Camguard is a clear liquid that looks a lot like water. It is a very good at corrosion protection when the engine is not ran for long periods of time.

I did an engine rebuild / replacement late in the fall one year. I ran it enough that I felt it was broken in but did not have the confidence that it would be ok switching to camguard for the winter. Instead, I used Phillips 20W-50 anti-rust for that winter. It is a fly away break-in preservative oil. IIRC, Phillips said it would be used for 10-hours for break-in or 25-hours of flying time. Since I did not fly a lot in PA during the winter, I wanted the best protection I could get but I also wanted to fly if Wx was nice and at or above 32 F.

That first winter, I used Phillips 20W-50 Anti-Rust but other winters in the east, I add Camguard for a little extra protection when I know it will be 2-weeks or more without flying. My normal go to oil is Phillips Victory 20W-50 but am also happy using AeroShell 15W-50 when I cannot get Phillips.

I would use the Anti-Rust oil on any engine that is almost new with less than 100-hours that would not be flown a lot in the winter. After 100-hours of flying, I would just add Camguard to whatever oil I like best.
 
I did get an oil analysis of the first oil change when I found the gunk in the strainer (Blackstone labs), and the recent change is enroute. They didn't see anything unusual in the original oil. That was not surprising, because the gunk was not soluble in oil or non-polar solvents -- gasoline, acetone, brake cleaner, etc. (So it probably was not carried much in the oil). It seemed to change character a little with alcohol or water, but not dissolve. I also sent some samples of the gunk itself to the lab, but they could not test it because their equipment requires it to be dissolved in a liquid, and they couldn't dissolve it either.

I do think the engine is pretty well broken in now, but "just". Cylinder head temperatures dropped a LONG time ago, the inside of my exhaust pipes is now grayish (rather than black and sooty), and I can't see discernible oil use over quite a few hours (say 5 or 6). Thanks for the idea of the Philips anti-rust oil. That sounds like a great interim step before the camguard, in case it's really not quite broken in yet. But, I think I'll avoid the "new variable" of additives for fear of prompting more rapid release of the gunk, since I don't really know what is happening with that (except it seems to be improving). However, I will use a dehumidifier over the winter. And at least it has fresh oil.

Ted
 
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Camguard is a clear liquid that looks a lot like water. It is a very good at corrosion protection when the engine is not ran for long periods of time.

I did an engine rebuild / replacement late in the fall one year. I ran it enough that I felt it was broken in but did not have the confidence that it would be ok switching to camguard for the winter. Instead, I used Phillips 20W-50 anti-rust for that winter. It is a fly away break-in preservative oil. IIRC, Phillips said it would be used for 10-hours for break-in or 25-hours of flying time. Since I did not fly a lot in PA during the winter, I wanted the best protection I could get but I also wanted to fly if Wx was nice and at or above 32 F.

That first winter, I used Phillips 20W-50 Anti-Rust but other winters in the east, I add Camguard for a little extra protection when I know it will be 2-weeks or more without flying. My normal go to oil is Phillips Victory 20W-50 but am also happy using AeroShell 15W-50 when I cannot get Phillips.

I would use the Anti-Rust oil on any engine that is almost new with less than 100-hours that would not be flown a lot in the winter. After 100-hours of flying, I would just add Camguard to whatever oil I like best.


You can also use Phillips Anti-Rust at a 10% rate indefinitely. It is an anti-rust product not an anti-wear. This makes it perfect for an engine that is not fully broken in and will be sitting for a period of time. For example when a plane is going in for paint.
 
You must be psychic! I let it go a little longer than planned; but just changed oil yesterday 12/2/22, at about 42 hobbs hours, which is approximately 20 additional hobbs hours since the last sample I would say its very similar to what I got the last time after 7 hours, so the rate of accumulation is slowing down. The oil filter is currently being drained -- I'll cut it open this week.

Getting on into Winter and long down times, I would like to start it on Camguard. So, dealing with this "stuff" in my strainer, I'm wondering whether a newly introduced additive (Camguard) will cause more of the strainer clogging "material" to be liberated. (I probably worry too much)

Thanks for the concern!

Ted

IMHO, oil and additives like camgaurd will NOT cause this type of debris on their own. I remain convinced that these are chunks of coke (burned/oxidized oil that is mostly carbon and why it is so hard and brittle). Most healthy engines do not produce that quantity of coke in 20 hours. In fact, sadly, many engines will go 100's of hours without the screen being pulled and have less coke than this.

The real question is where it is forming. Typically ring/wall interface issues allow too much oil on the walls and this allows excessive oil to build up near the compression rings and causes excessive coked oil around the rings. Over time it breaks off and ends up in the oil pan, eventually being pulled into the screen.

I saw this in the first 10 hours on my 320 (looked like the pics in your first post). In that case, 2 cylinders were glazed and I re-honed. I now only check the screen at annual and rarely see more than 5 of those small chunks. Same on my 540.

FYI, the debris you are seeing is NOT rust. If all of that debris were iron based, you would be in deep trouble.

I would at a minimum, keep checking the screen at every oil change, as you are at a much higher risk of fully clogging it than most engines. That can change if you continue to see a downward trend in debris production. The fact that you flushed the oil pan out means this is newly created coke and not simply stuff from the first 10 hours fianlly making it's way to the screen.

Larry
 
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Theory

Any theories why the black crud is not seen in the filter? Is it normal to this much in the screen and little to none in the filter?
 
Any theories why the black crud is not seen in the filter? Is it normal to this much in the screen and little to none in the filter?

My guess is that its the contents of a dessicant bag. Cylinder kits come with them tucked into the backside of a piston.
 
My guess is that its the contents of a dessicant bag. Cylinder kits come with them tucked into the backside of a piston.

Could be, Bob, but wouldn't some silica dust end up in the oil sample as silicon?

Or - maybe it is clay, and not silicon ??
 
Surely some of this would make it to the filter

Surely some of this would make it to the filter
 

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Surely some of this would make it to the filter

There WAS a little in the filter. However, very little -- probably 100x more in the strainer by visual inspection. Of course, possibly the little bits that got through bumped around awhile and got even smaller so that they "dissappeared" in the larger area filter media. The material in the strainer is probably more akin to very viscous pitch. If you move it quickly, it crumbles or breaks, but with steady pressure, seems to extrude. It seems to soften with exposure to air, and essentially is absorbed if left on a paper towel for a few weeks. What came out the crankcase with the earlier flush, however, was thin flakes, maybe 1/2" x (say) 0.02". This material behaved the same as the stuff in the strainer -- I think that it is one and the same. I think it just balls up in the strainer, gets stuck to the walls, and then starts to extrude through the 0.040 strainer holes.
 
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IMHO, oil and additives like camguard will NOT cause this type of debris on their own. I remain convinced that these are chunks of coke (burned/oxidized oil that is mostly carbon and why it is so hard and brittle). Most healthy engines do not produce that quantity of coke in 20 hours. In fact, sadly, many engines will go 100's of hours without the screen being pulled and have less coke than this.

The real question is where it is forming. Typically ring/wall interface issues allow too much oil on the walls and this allows excessive oil to build up near the compression rings and causes excessive coked oil around the rings. Over time it breaks off and ends up in the oil pan, eventually being pulled into the screen.

I saw this in the first 10 hours on my 320 (looked like the pics in your first post). In that case, 2 cylinders were glazed and I re-honed. I now only check the screen at annual and rarely see more than 5 of those small chunks. Same on my 540.

FYI, the debris you are seeing is NOT rust. If all of that debris were iron based, you would be in deep trouble.

I would at a minimum, keep checking the screen at every oil change, as you are at a much higher risk of fully clogging it than most engines. That can change if you continue to see a downward trend in debris production. The fact that you flushed the oil pan out means this is newly created coke and not simply stuff from the first 10 hours finally making it's way to the screen.

Larry

Agree its not CAUSED by camguard because it wouldn't make sense and hasn't been used yet anyway. I was just thinking if the source is excess sealant that dripped into the crankcase during assembly and is breaking loose, a new additive in the oil could possibly accelerate the process. Whatever else I might do, I'll be checking that strainer frequently!

But lets assume it is the coking that you suggest, since that could be the correct sort of material, and assess if it matches. I observed flakes in my oil sump. Could the coke you described be released to the oil as large flakes? I would think that even if liberated as flakes, they would come apart in the chaotic crankcase before making it to the oil drain passage to the sump. What did you see in that regard? Was it granular in the sump, or flaky? I don't think my material is granular until I break it loose from the strainer. However, I suppose coke could re-coalesce in the strainer or sump as particles accumulate on top of each other.

Related observations: My oil consumption seems OK. i don't have enough operating time to really dial in the number, but I lost about 0.1" on the dipstick in the last 5-7 hours of operation. So that's maybe 25 hours per quart. (However, 0.1" is hard to read, since it varies that much as the oil settles). Also, compressions were pretty good when last checked, all 80/80 except one cylinder (number 2 by memory) was 75/80. I will recheck before I do a lot more flying. Of course, I suppose its possible that all cylinders except one, are OK, and that one accounts for the issue. That might not affect oil use appreciably. Spark plugs look OK to me.

Pulling the string a little further, though, is there any good way to tell without pulling the cylinders? We did look at the cylinder walls visually and with a boroscope. I don't recall seeing an amber glaze, but perhaps my "skill of the craft" is not up to snuff.

One thing I have noticed is that after startup, before getting up to operating temperature, cylinder 4 leads the pack. Nothing out of bounds, but clearly higher than the others until fully warmed (both in CHT and EGT). At power it is in the pack and not the hottest. I had attributed that to fuel distribution, but I suppose it could be something mechanical. Also, for what its worth, the Titans have Ni cylinders.

Thanks again.

Ted
 
...

Pulling the string a little further, though, is there any good way to tell without pulling the cylinders? We did look at the cylinder walls visually and with a boroscope. I don't recall seeing an amber glaze, but perhaps my "skill of the craft" is not up to snuff.
...

From what I understand, you should be able to determine if a cylinder is glazed using a borescope, and there is no need to pull a cylinder. Also, there is a lot of risk in pulling a cylinder, according to Mr. Busch:

https://www.youtube.com/watch?v=I4tzOAaNfyQ

https://resources.savvyaviation.com/wp-content/uploads/articles_aopa/AOPA_2020-03_risky-business.pdf

I'd also think that just having one cylinder glazed would be unusual. Keep in mind that cylinder compression tests can be inconsistent, so after flying for an hour, the number can change.
 
When engine parts are made they are coated with a lacquer to prevent rust during storage. If they are not thoroughly cleaned before assemble then that lacquer could be some of the source of the "crud" in your filter screen.

You have made no mention of your break-in method so as a reminder Lycoming says (in my words) to run the engine "hard", don't baby the it. Obviously keeping in within correct temp limits, "fly it like you stole it". That's what I did with the engine O-320 on my previous -4 and it turned out great, the engine was tight burned very little oil approx 1 qt in 20-25 hrs.

Hope this is all a false alarm for you.

Glenn
 
Agree its not CAUSED by camguard because it wouldn't make sense and hasn't been used yet anyway. I was just thinking if the source is excess sealant that dripped into the crankcase during assembly and is breaking loose, a new additive in the oil could possibly accelerate the process. Whatever else I might do, I'll be checking that strainer frequently!

But lets assume it is the coking that you suggest, since that could be the correct sort of material, and assess if it matches. I observed flakes in my oil sump. Could the coke you described be released to the oil as large flakes? I would think that even if liberated as flakes, they would come apart in the chaotic crankcase before making it to the oil drain passage to the sump. What did you see in that regard? Was it granular in the sump, or flaky? I don't think my material is granular until I break it loose from the strainer. However, I suppose coke could re-coalesce in the strainer or sump as particles accumulate on top of each other. If you have sheets of stuff, it is not COKE IMHO.

Related observations: My oil consumption seems OK. i don't have enough operating time to really dial in the number, but I lost about 0.1" on the dipstick in the last 5-7 hours of operation. So that's maybe 25 hours per quart. (However, 0.1" is hard to read, since it varies that much as the oil settles). Also, compressions were pretty good when last checked, all 80/80 except one cylinder (number 2 by memory) was 75/80. I will recheck before I do a lot more flying. Of course, I suppose its possible that all cylinders except one, are OK, and that one accounts for the issue. That might not affect oil use appreciably. Spark plugs look OK to me.

Pulling the string a little further, though, is there any good way to tell without pulling the cylinders? We did look at the cylinder walls visually and with a boroscope. I don't recall seeing an amber glaze, but perhaps my "skill of the craft" is not up to snuff.

One thing I have noticed is that after startup, before getting up to operating temperature, cylinder 4 leads the pack. Nothing out of bounds, but clearly higher than the others until fully warmed (both in CHT and EGT). At power it is in the pack and not the hottest. I had attributed that to fuel distribution, but I suppose it could be something mechanical. Also, for what its worth, the Titans have Ni cylinders.

Thanks again.

Ted

The particles in your pics match what I saw. Jet black in color, squarish shaped, jagged edge particles about a 1/16" in size and very hard and brittle - will change to dust (dry) or oil like liquid (saturated) when squeezed between fingers. When there is too much oil on the walls, it pools on top of the top compression ring and the extreme heat from combustion cokes it. It forms in the ring land area and eventually fractures from the ring movement, making the particles. This type of coke would never come off in sheets, as it is very brittle and couldn't make it to the pan that way.

There is a good chance that you just had too much oil on the walls during the break in period and it created a lot of coke in the lands. Possibly it has stopped producing coke and will take some time for all that is there to break off and make its way to the pan. This would be seen as a continual decline in particles seen in the screen.

Glazing is the top cause for oil burning in a new or overhauled engine, post ring seating. You can see most glazing by peering in through the spark plug holes. Look through one hole with flashlight in other hole. A borescope will allow for a full examination. Unglazed walls will be shinny silver with defined cross hatch. Glazing is seen as a tan or brown opaque coating on the walls and you will not be able to see the cross hatch. Glazing does not affect compression, depending upon how early in the ring seating process it formed, so 80/80 is not definitive for unglazed walls. Glazing is not a death sentence; It's only side effect is excessive oil consumption, however, in this case you must be vigilant about cleaning the sump screen as it will continue to make coke particles.
 
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Any theories why the black crud is not seen in the filter? Is it normal to this much in the screen and little to none in the filter?

Yes that is normal. Usually will see a few in the filter, but not many. While coke is hard and brittle, it is not strong (you can crush it into dust between your fingers) and cannot survive the compression between the two gears in the oil pump, which is between the screen and the filter. Charcoal is a good comparison material for coke.
 
Larry -- I realized that I described, but did not attach any photos of the flakes in the oil sump. These were from May/June, when I flushed the oil sump. They are in a small plastic drinking cup in the photo. When these came out with the kerosene, they were brittle and would shake around in the cup. 2 days later, fully adhered to the cup. I also attached a couple typical shots of the cylinder walls.

Thanks
Ted
 

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Larry -- I realized that I described, but did not attach any photos of the flakes in the oil sump. These were from May/June, when I flushed the oil sump. They are in a small plastic drinking cup in the photo. When these came out with the kerosene, they were brittle and would shake around in the cup. 2 days later, fully adhered to the cup. I also attached a couple typical shots of the cylinder walls.

Thanks
Ted

No idea what the flakes are, looks like varnish. The cylinders look perfect.
 
Larry -- I realized that I described, but did not attach any photos of the flakes in the oil sump. These were from May/June, when I flushed the oil sump. They are in a small plastic drinking cup in the photo. When these came out with the kerosene, they were brittle and would shake around in the cup. 2 days later, fully adhered to the cup. I also attached a couple typical shots of the cylinder walls.

Thanks
Ted

Have no idea what those sheets are. but know they are not coked oil Reminds me of peanut brittle without the peanuts, though probably not a good idea to taste it:). also pretty confident that the black chunks did not start out as part of those sheets. Cylinder walls look good with no signs of glazing. Be advised that glazing can and often does only appear in certain spots on the cyl walls.

Larry
 
There is a good chance that you just had too much oil on the walls during the break in period and it created a lot of coke in the lands. Possibly it has stopped producing coke and will take some time for all that is there to break off and make its way to the pan. This would be seen as a continual decline in particles seen in the screen.

Physically impossible as only fine particles can pass due to ring and piston clearances. Large-ish carbon particles that end up in the oil filter come from oil oxidizing on hot exhaust valve components such as the springs and valve spring seats. I spent some time yesterday scraping this stuff off these components on a Continental.

The larger sheets look like the remnants of wax paper wrist pins are wrapped in. Just a guess of course.
 
Have no idea what those sheets are. but know they are not coked oil Reminds me of peanut brittle without the peanuts, though probably not a good idea to taste it:). also pretty confident that the black chunks did not start out as part of those sheets....

Larry

Well, I am pretty fond of peanut brittle, so I'm tempted! The funny thing is that the "black" chunks from the strainer become more and more amber color as they are exposed to air. However, even when "black" they are really just very dark brown when held to strong light or microscope. Perhaps they are dessicated a little by hot oil, and pick up moisture after exposure to air??? Mystery.

With luck it will continue to decrease. The first time, it was alarming, being a surprise and 50% plugged in 15 hours. This rate of plugging is way less --worrysome, but I'm going to keep checking all parameters frequently.

Thanks to everyone for your inputs. It really helps. I'll post again if anything changes for better or worse, or for any new revelations.
 
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Physically impossible as only fine particles can pass due to ring and piston clearances. Large-ish carbon particles that end up in the oil filter come from oil oxidizing on hot exhaust valve components such as the springs and valve spring seats. I spent some time yesterday scraping this stuff off these components on a Continental.

The larger sheets look like the remnants of wax paper wrist pins are wrapped in. Just a guess of course.

We'll have to agree to disagree, as in my case with glazed cylinders on my freshly overhauled engine, I got a VERY LARGE quantity of those coked oil chunks in the screen in just 10 hours of operation. I honed the cylinder and installed new rings to address the issue and in the 850 hours since have not seen more than 10 or 20 of those chunks in the screen.

I have no idea how they get from the piston to the oil pan. I just know that they did. Ring lands were fully clogged with coked oil on disassembly, as were the piston walls between the lands. No other areas observed with coked oil, including the exh valve area. I believe the chunks migrate behind the ring to get from top to bottom. The ring is constantly moving between the top and bottom of the ring land.

I can't remember if there was coked oil on the piston below the oil ring, but that could easily break off and get to the pan.

Just stating cause and effect here.

Larry
 
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Well, I am pretty fond of peanut brittle, so I'm tempted! The funny thing is that the "black" chunks from the strainer become more and more amber color as they are exposed to air. However, even when "black" they are really just very dark brown when held to strong light or microscope. Perhaps they are dessicated a little by hot oil, and pick up moisture after exposure to air??? Mystery.

With luck it will continue to decrease. The first time, it was alarming, being a surprise and 50% plugged in 15 hours. This rate of plugging is way less --worrysome, but I'm going to keep checking all parameters frequently.

Thanks to everyone for your inputs. It really helps. I'll post again if anything changes for better or worse, or for any new revelations.

You may be right and hopefully correct. All the coked oil that I have seen is jet black, like coal, and cannot be confused with dark brown and exposure to air or bright light doesn't change it's color.
 
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I am researching coking further. I think that is very possibly the right track, just not at the piston rings in this case. Apparently, in the process, when oil is heated to >500F or so, over time, it uses up any anti-oxidants in its formulation, and begins a transformation to where it is no longer oil soluble, darkens, and proceeds on a continuum until its essentially black carbon. The material is apparently sensitive to humidity, which can cause it to flake off after it builds up awhile. Surely, this happens on the bottom of the piston crowns, but everybody would have that, I would think. My flakes look like they were formed in the oil sump -- maybe? But---It would take a pretty high heat flux to locally heat a film to that temperature with the bulk oil temperature having always been normal (180F-205F) The only big source of heat there would potentially be radiant heat from my exhaust crossover pipes. (see inverted manufacturer's stock photo) But it is also possible that continental/titan had some "other" oil in there that I didn't know to flush out, and that made the deposits. So, maybe my problem is already gone. Nonetheless, I will add heat shields on the crossover pipe near the sump, just in case. Note: I have mufflers and low compression (8.3:1) pistons, both of which would tend to increase crossover pipe temperature.

Any coking / petroleum experts out there???

Thanks again
Ted

A couple coking phenomenon articles I found:

https://www.silmid.com/Documents/COKING.pdf

https://aeroenginesafety.tugraz.at/doku.php?id=22:223:2232:2232
 

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Occam’s Razor

I vote for Occam’s Razor.
It seems to me the simplest explanation is the desiccant bag under the piston wasn't removed. JMHO
 
I vote for Occam’s Razor.
It seems to me the simplest explanation is the desiccant bag under the piston wasn't removed. JMHO

Had to look that up --- hey, that's my favorite razor! :eek:
 

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Surely, this happens on the bottom of the piston crowns, but everybody would have that, I would think. ]

I have never found fully formed coke on the bottom of a piston. Stops somewhere on the continuum you described. It leaves a thin dark brown coating on the piston bottom, like varnish, but no coke. Splash oil does a good job of cooling the piston bottom. Only place I have seen it is on the sides of the piston and in the ring lands, as they see the super heated combustion gases. Also common on the stem and tulip area of exhaust valves when the guides are loose or seals have failed (no seals on Lyc's).

Your theory makes good sense, at least for the large flakes, but do question whether that area can get hot enough to make the actual hard carbon chunks. Anything but an expert in this area unfortunately. This theory is far more likely than dessicant making those large flakes. Dessicant is typically silica and that is white in color. Unsure if heat turns it dark brown, but do not believe that it does. Sorry, not a chemist. Also, the melting point of silica is over 3000* Therefore quite unlikely that it converted from small beads into cohesive sheets in your oil pan.

Larry
 
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For closure, just started my 2023 condition inspection with a look at my strainer. It was nearly 100% clean. Currently about 50 hobbs hours total time on engine since new. Yipee!!

(I did add a few heat shields between pipes and oil pan, but I doubt they are actually needed since nobody else reported this issue and crud amounts seemed to be decreasing anyway.)
 
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