Blow By Question

Time to dig in before you have to dig the seat cushion out!

Well we have all piled onto the bearing idea and I think it is with very good reason BUT you could do the world a favor (not by flying anymore) by having your mechanic do the stethoscope test before pulling the engine. It would be interesting to me that if it does come up a bad bearing that there might be a way to check externally for someone in the future. I have a couple other ideas to try and confirm at least my idea before we all send you barking up the "golden tree" of teardown: Unscrew the 90* breather fitting and borescope that area. You can see the ends of the two front bearings and maybe the cam end. Also look for a pile of chips or just some chips inside that settling area maybe at the bottom. Rather than my crude barnyard melting test you could send those chips in for a real analysis also. I hate guessing in troubleshooting if by thinking through the problem you could come up with innovative tests to avoid wasting time and money and up the confidence level on a theory but the real mechanics seem to agree your done risking your life with that much metal absent exploratory surgery. Also you already have the airspeed indicator (unless you can send it back) and you could confirm with a aborted takeoff run down the runway that you don't have excessive crankcase pressure before the tear down. These would all be great test points for future "blow by" problems of others.

One last thing: If the teardown agency finds that nothing is wrong inside you will be on the hook. Not those giving advice from experience or those of us trying to think our way through this. None of us can confirm any of your reports or tests and so ultimately it's just "free advice". I know what I would do if it were mine (Actually I would confirm all this farther on the ground before a teardown even though I think I've nailed it. I have thought that many times before in situations like this and been completely wrong!) Nope, just a bit more until no further practical tests can be made and THEN throw the dice on a teardown. Analysis of those chips is cheap and will only cost a week or two and the rest of the engine removal could start while the're being analyzed. But from my perspective please don't fly it anymore until you actually know! SJ can't afford to lose a subscriber. Good luck!!

N86250 said:

I think that is a lot of metal for any engine new or old. I don't think that is coming from pistons. I think that is from the wrist pin plugs or from the case-cam bearings or lifter bores. Maybe the thrust bearing is spun. I think it's time to stop flying and tear it down. jrh

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This is an excellent possibility and another possible way to up the confidence on the idea that a bearing is going: If your headed to a teardown anyway the first step is to pull the jugs and inspect for piston pin plugs sluffing metal and pistons scoring etc and all the rest of the cylinder makeup. If you don't find anything to explain the pile of metal there then it's on to the gearcase and THEN if nothing is found, well then the confidence in a teardown being needed approaches 99% I would think.

I have been researching possibilities and options while pondering my next move. Based on the info contained in Lycoming SI 1492D and the following articles, I have decided that my very next course of action is to take my little pile of shiny metal flakes and a sample of the oil to AvLab in Houston tomorrow to have all of it analyzed. In the mean time, I am waiting on an email or phone call from Mena Aircraft Engines probably on Monday or Tuesday.

I have been doing a lotta research on this, and the following three articles are what prompted me to go to AvLab to find out exactly what this stuff is and exactly where it is coming from. I will let yall know what the results of the analysis is as soon as I get the report back. This will help determine my next move. From what I read in the article, this could very well be flakes of chrome, from the chrome rings, which could be related to the blow-by.

Lycoming SI 1492D (even though it specifically does not apply to the O-235, it is good info to go by).

http://www.avweb.com/news/savvyaviator/190242-1.html?redirected=1

http://www.supercub.org/forum/showthread.php?44224-Metal-in-Filter-Article&highlight=metal+screen

http://www.aopa.org/News-and-Video/All-News/2010/May/1/Airframe-and-Powerplant-Engine-making-metal

I didn't realize you had taken an oil sample. I would send it in with a little of the metal. We use them at work for the equipment. I know they like having a base line to start with but they should be able to give you some good info with the sample. It breaks down how much of each element is in it. They will come in with caution high levels of ---- if something's high plus still give you the levels of everything in the oil. It'll give you an idea of where the metals coming from without opening the engine up.

574cub, yeah, that's why I wanna do an oil analysis before I do anything else, to see if this problem can be solved without having to open the engine up. I will open it up if i have to, but prefer to open the engine as a last resort. If the oil analysis pinpoints where the metal flakes are coming from, then I will have a better idea of what is going on here.

Barnstormer, sorry I didn't make it over there today, sure wanted to though. Talked to CenterHillAg when he landed after getting back from Louise, said it was a bit muddy over there from all the rain we got last week. I'll make it over there one day soon though.

salex, Air-oil separators do a very good job for "normal" nuisance breather fumes. Desperado's engine has much more serious problems than would be covered with a separator. That little pile of metal chips is the proof.

I wouldn't move the propeller on an engine making that much metal. Engine probably has his spun bearing. Take the whole thing back to the mechanic that did the overall thirty hours ago.

salex said:

While we wait for our poor Texican friend to give us his next report so that we know exactly how we ought to commiserate with him over his economic insult, I wonder if you might entertain an expansion of this subject. This has been on stunningly interesting thread for a new member to follow. Please have grace for any obvious novice errors I make. Though I have owned my plane for almost 20 years now, I still feel like I do not know much about maintaining it.

I kept waiting for someone to bring up this subject as the thread progressed and am a bit surprised that no one did - the subject of these "air-oil separators" that we can put in place of the breather tube. Like everyone else, my tired 0-320 with 1900 hours kept me with an "oily side" to "keep down." At overhaul about 10 or so years ago - while shedding every pound possible in general - I added the one thing that I had not had before - the M20 Air-Oil Separator. I love it. Absolutely love it. I fly with all 8 quarts of oil in - and it stays in. I change oil and filter every 25 hours and usually only add one quart of oil during those 25 hours, though it will always be down to 7 quarts when I change it. (Net result being "using" two quarts max in 25 hours.) I can tell that it helps with oil cooling on hot summer days, and I have always figured that surely it helps with overall engine health.

However, this thread has made me wonder what I might be missing in terms of diagnostic clues about actual or approaching problems by not having the breather tube issues to catch my attention. I do not know enough to even really start to think that through. Anyone want to venture some ideas for me? Is the reason that no one brought this up because these air-oil separators are a horrible idea and I am just the only one on the planet who does not know that? Are there some true and costly downsides to having one? Thanks, Alex

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I too have been thinking of the future where this thread is concerned. It would be neat after it's all over to go back and have a couple of engineers, our experienced IA's and A&P's, experienced Experimental builders Diesel mechanics etc. go over the whole thing, synthesize the information and come up with a troubleshooting tree, % likely hood of symptoms pointing in a given direction, ways to arrive at a "valid" conclusion and kind of start the grandaddy of all air cooled aircraft engine threads that others could use to help avoid costly or even deadly problems. One of my fears is that if there is an internal case problem and the agency repairs it but doesn't (and if they repair it it is well within their rights in my opinion to keep what they find to themselves for whatever reason) tell what they found or why the we might not have anything but a "black box" conclusion. Under that situation we won't be able to really tell what all the symptoms meant logically. If it is internal then this thread is even mis named as it wouldn't be "blow by" as such.

Alex I don't know anything about oil separators BUT based on Desperado's baby bottle experience here is a question: What happens if the seperator was to get overloaded by oil? Would your engine "load up" as Desperado experienced? Loss of power? Probably your minutes or seconds away from that anyway but what would the consequences be of blockage? Do you slit the hose above the separator as a point of installation?

qsmx440 to your question on a blocked breather. I've seen it a couple times on the slope. In the cold the moisture will freeze the extended tubes. The pressure has to go somewhere on the diesels it pushes the dipstick up and the oil out. I've saved a couple finding them in time and I've also seen a baseball size hole in the block from one that didn't get found in time. While the dipsticks are threaded in and can't get blown out it'll blow a seal somewhere to vent the pressure.

Alex I don't know anything about oil separators BUT based on Desperado's baby bottle experience here is a question: What happens if the seperator was to get overloaded by oil? Would your engine "load up" as Desperado experienced? Loss of power?

When I removed the baby bottle, the loading up totally went away. The tip of the vent tube was only an inch and a half down past the lip inside the baby bottle, and it caused the engine to load up, like it had excessive back pressure in the crank case. I do not have the whistler notch in the vent tube. When the baby bottle filled up with oil from the blowby, I think it caused back pressure which caused the engine to load up. In the cockpit I can't see how much oil is in the baby bottle, but that is my perspective.

One thing I have noticed on mine is that you have to have the baby bottle opening not tight around the vent tube. Mine has 3/8 or better all the way around, and tube is half way down inside.

SteveE said:

One thing I have noticed on mine is that you have to have the baby bottle opening not tight around the vent tube. Mine has 3/8 or better all the way around, and tube is half way down inside.

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Yeah, mine was at least 3/8" all the way around, maybe more like a half inch, but I am just going from memory, I didn't measure that. There was plenty of clearance though.

qsmx440 said:

I too have been thinking of the future where this thread is concerned. It would be neat after it's all over to go back and have a couple of engineers, our experienced IA's and A&P's, experienced Experimental builders Diesel mechanics etc. go over the whole thing, synthesize the information and come up with a troubleshooting tree....

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qsmx440, I have been looking at this from the point of view that it was a normally running engine which developed a problem. In reality it is a newly overhauled engine which appears to have had some error in the overhaul. ( I am not pointing fingers at anyone here. The Error could be a part malfunction or human. We don't know.) This error took 30 hours to show up. I do believe that trying to analyze an engine's troubles from an already running well for a long time engine and one which was recently overhauled requires a different perspective.

A properly designed and installed oil separator will do a good job of stopping excess breather oil from escaping.

I have had a screw in dipstick blow out when the breather froze over, dumping most of the oil overboard.

DesperadoPilot said:

Alex I don't know anything about oil separators BUT based on Desperado's baby bottle experience here is a question: What happens if the seperator was to get overloaded by oil? Would your engine "load up" as Desperado experienced? Loss of power?

When I removed the baby bottle, the loading up totally went away. The tip of the vent tube was only an inch and a half down past the lip inside the baby bottle, and it caused the engine to load up, like it had excessive back pressure in the crank case. I do not have the whistler notch in the vent tube. When the baby bottle filled up with oil from the blowby, I think it caused back pressure which caused the engine to load up. In the cockpit I can't see how much oil is in the baby bottle, but that is my perspective.

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Yes you were inserting a "pressure relief valve" where you don't want one. The bottle would fill till the tube end was covered and then the pressure started building in the crankcase until finally a "puff" came along and blew a bunch of oil out of the bottle starting the whole process over again. Probably if you really had been experiencing actual blow by you never would have had the symptom as the pressure would have been much more excessive with each power stroke and blown the hose right out of the bottle.

skywagon8a said:

qsmx440, I have been looking at this from the point of view that it was a normally running engine which developed a problem. In reality it is a newly overhauled engine which appears to have had some error in the overhaul. ( I am not pointing fingers at anyone here. The Error could be a part malfunction or human. We don't know.) This error took 30 hours to show up. I do believe that trying to analyze an engine's troubles from an already running well for a long time engine and one which was recently overhauled requires a different perspective.

A properly designed and installed oil separator will do a good job of stopping excess breather oil from escaping.

I have had a screw in dipstick blow out when the breather froze over, dumping most of the oil overboard.

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30 years ago I left the oil cap off on my O300 after adding a quart for a longer flight. I lost half the oil in the next 2-2 1/2 hour flight. A dipstick or oil cap make lousy breathers ;-)

Sky I think 20-20 hindsight will show Desperado could have gotten there a lot faster and cheaper with better questions and maybe testing? For instance rebuilding cylinders that had good compression but "slight glazing" was just a waste of time and money IMHO considering 5 quarts an hour was going overboard and the whole blow by question (upside down rings etc.) could have been laid to rest with a crankcase pressure test as Steve requested. Any broken ring causing this much fuss should have shown up with the bore scope. I question has anyone experienced 5 quart an hour loss in a 200 Cubic Inch engine from rings not seated? Could save a future someone a lot of time and money and maybe their life by going over this thread. Of course that"s considering were not blowing smoke now! Removing non standard mods like the baby bottle would have helped to not muddy the waters with related but unimportant symptoms (Although Desperados "problem" has convinced my to leave the baby bottle with the grandkids).

I'm glad to see Desperado is getting the metal checked before further action.

Salex I don't know how cold it was with skywagon's freeze up. Normally on the slope from what I've seen its been when it was cold mid-30's to mid -50's on equipment that's been parked. There idled up but there's not enough heat for the long factory breather tubes. Up there we just take the tubes off depending on how tired the engine is it can make a mess. There's a lot of factors in it, how tired the engine is and how much blow by its making. How much moisture is inside. Where the breather or oil separator is and how much heat its getting to stay thawed. I don't think it happens on aircraft engines as much. If you have gotten almost 2000hrs out of your engine without a problem you should be fine not to say it couldn't happen though. I haven't been around a plane with a separator on it to see where it is and how much heat it would get. I would guess they did some testing on it to find out before selling them.

574cub said:

Salex I don't know how cold it was with skywagon's freeze up..

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This happened 50+ years ago. It was on a clear dry cold winter day in New England at about 5500 feet. Temperature was below zero. After about 30 minutes of flight, the breather formed a large chunk of solid ice over the outlet which was protruding a little more than an inch below the bottom cowl. There was a loud bang from the engine (dip stick hitting the cowl) followed by a loss of most of the oil pressure. Looking out the window, oil was seen out to the tip of the stabilizer. Following this event there was an AD note issued to install a whistle in the breather pipe inside the warmer cowl area. Mine was not the only one. I know of at least one other which crashed and was destroyed. I made it to an airport.

AD 64-17-05
http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAD.nsf/AOCADSearch/DD6BF956A08C4CB386256A5400439654?OpenDocument

This thread has taken another interesting twist.

Sky was that rime icing do you think? In any event it wasn't from moisture in the engine freezing as it exited the pipe. Correct? Not much point in conjecture on the effect a separator would have had on Desperado's problem until we know for sure what the problem is. BUT, always with the but, if it's inline with the hose and if there is no "whistle" slot then it would have potential to block in the first and maybe mask a symptom in the second? To know if a separator could mask a symptom (Silex's original question) we would need to know the oil removal rate at a given crankcase pressure (voltage) and hose volume (current) needed for that rate or a curve on a pressure/volume chart. If it turns out Desperado's problem is a bearing well the only symptom he has had actually is oil loss. Would a separator have been a good thing (retaining the oil) or a bad thing (masking the only symptom)? This might deserve a thread of it's own after we know what is actually causing Desperado's problem.

Has anyone thought of how a better engine monitoring system could be designed to include bearings in the picture? My 3D printer uses cheap and tiny thermistors to measure hotend temperatures accurately from outside temp to 4-500 degrees.. Less than 2-3 bucks each and maybe 1/16 by 1/8 inch glass drop. They just push into a small hole in the aluminum near the heater and Kapton tape keeps them there. A cheap Arduino controller (RAMBo) could keep track of them and the trends (along with running the autopilot, navigating and making coffee etc.). I'm talking experimental of course as I'm sure some company could turn a 100$ accessory into a 10,000 dollar monitoring system! Tiny transducers could also detect a bearing going (or already gone even though the engine is happily running on 3 compromised bearings instead of four good ones as in my pictures. Once calibrated a small audio amp with a threshold indicator (squelch circuit) could indicate a bad bearing by the huge increase in noise.

Crankshafts are way stronger than I thought.) I always thought oil pressure would tell the bearing story until hearing the story behind the engine I posted pictures of. Very disturbing to know you may only see oil pressure drop when your engine quits. Oil pressure it appears is not necessarily a trend indicator and that would be a good thing to have since it appears these engines seem to eat themselves for a while before quitting. Without a "trend" warning, the engine reliably running for a while as a grinding machine is not of much use to you if you don't know it's giving you it's last few minutes to land and worse yet the final silence may come during the next takeoff.

Just scaned over this thread so don't know if it was mentioned, but my first thought would be that steel rings were put in steel barrels or chrome rings were put in chrome barrels. That would cause the blow by and metal in oil. SOA will only look at PPM, it is for trend monitoring and is really unneeded in a piston engine when you have a hand full of metal to look at with the naked eye. A good mechanic should be able to tell you where it is coming from. If I majored a engine and it made more than a few slivers of metal on break in I would want it back in my shop right away before any more damage is done.

qsmx440 said:

Sky was that rime icing do you think? In any event it wasn't from moisture in the engine freezing as it exited the pipe. Correct? .

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It was not rime. It was a severe cold CAVU winter day. The only possible source of moisture was from the engine breather. The outside air temperature was so cold that the breather moisture froze as it exited the pipe. It formed a large golf ball sized chunk of ice.

SuperCub MD, AvLab has a test kit for Lab Analysis of Small Particles, Kit No. AVL-CK, for $110 that will analyze the small metal flakes and tell me where they came from. I called them and was told that to test the flakes and a 2 ounce sample of oil would cost $129 total. If it was just metal particles, only $110. Just to test a small sample of oil alone is only $20.95, test kit No. GA-001-SP. This is where I am sending my metal flakes and oil sample to for testing.

http://www.avlab.com/searchresults.asp?cat=1996

The kit I will be using is GA-001-OF-CK for $129, which will test both, the flakes and a sample of the oil.

DesperadoPilot said:

Yeah, I am beginning to think a teardown is in my near future as well. I am also starting to think that the blow-by problem and the metal in the screen are two seperate issues as well. But then again, what do I know. Actually, not much of anything, according to my wife.

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I've been watching this thread with interest since it's inception, and would have commented, but didn't see that I had anything to add, as the normal diagnostics weren't making sense. However, looking at the big picture, and the metal from your screen, I do have a few thoughts.

1. No need to send the metal flakes off for analysis. Any time the engine makes that much metal, the source will be obvious when you tear it down, and it needs to be torn down!

2. The bogging down is consistent with a bearing seizing and spinning and is likely coincidental to the breather and baby bottle. IMHO, that's a red herring.

3. The 30 hour time frame is consistent with the time frame for an improperly torqued bearing to fail, often times failing the case with it when the bearing spins as shown in the photos from QSMX40. Of course when you removed the top end, the bearing would have been re-torqued upon re-assembly if it was a center bearing. If it's a front bearing and is spraying oil into the breather area, then it likely wasn't re-torqued during the top overhaul.

You are at a point now where the problem will be obvious upon tear down of the case, so that's where I would go with it. Whether you do it locally, or take it back to the shop that did the original overhaul is up to you. Since the top end has been off since they last saw it, they may not want to warranty the work, so you may have to work with them a bit to convince them the top overhaul was due to the problem, rather than the problem being caused by an unneeded top overhaul following their major overhaul.

If you were in this part of the country, I would do the engine tear down for you for free just to satisfy my curiosity.

-Cub Builder

I guess I didn't get the right point across. Chunks are chunks, in a new engine it doesn't matter what flavor they are. They are embedding in the soft tissues of your engine like your crank bearings and piston skirts, every turn of the engine at this point is making a lot of wear to expensive parts. My advise is to get it back to the overhauler, if they will stand behind their product at all they will want to find a answer before further damage is done. My first guess is still incorrect type rings, as I have seen this before. If my guess is right you will ruin the entire engine by continuing to run it.

That pile of metal, is what got screened out. The smaller stuff, is still circulating, when the engine is run. In the interest of saving parts, no matter what the source of metal is, it seems prudent to have a very well qualified person disassemble carefully, looking for the source. As has been implied previously, I surely do hope the engine is diagnosed by someone who has the integrity to be transparent about what is found. I hope that looming liability and reputation concerns, do not pressure someone or some organization to be less than candid about what they discover. As of now, this problem has not hurt anyone, other than financially.... I fear, that if this were my engine, I would not be so methodical in diagnosis, nor so gracious with everyone who has twisted wrenches on it, as has been it's owner. Unforeseeable failures, do occur in the creation and use of mechanical devices.. There may be human error involved, or just plain unexpected failure of materials. One way or the other, this problem has to be solved, and likely it is more significant than a little too much blow by. That metal pile, frightens me. Not that I know so much, but never have I found even a small portion of that amount of metal, in any of a multitude of screens I have cleaned. I desperately hope this gets resolved satisfactorily, before any additional unnecessary expenses are created. It is with considerable chagrin, that I recall early on in this conversation, promoting the idea of running this engine real hard under load for a while. My sense is that this is no insignificant problem, and I sure don't want someone to get banged up or another airplane bent and in the news. Turns out that free advice is worth about what is charged. This discussion has been engrossing, and might even be entertaining, if the cost, and stakes were not so high. I, as likely do many others, anxiously await an unpacking of the findings, conclusions, and resolutions in this problem.

The only engine I ever saw with more metal in the screen was an A65 Continental lying on the floor in the corner of a hangar. It was offered as a no logbook core for cheap. When the oil screen came out it was totally plugged with large aluminum flakes and it had collapsed. The case was junk, the crank was junk, the cam was junk, one cylinder, piston, and wristpin was junk for sure. Nobody measured the other three cylinders to see if they could be ground oversize and they needed it if they were still standard. It was a first class genuine boat anchor. Wristpin cap got into the cylinder wall to deeply score the cylinder and create the aluminum that plugged the screen and the lack of oil circulation took care of everything else. The stuff in the screen of this poor motor would have made a bigger pile of cuttings than Desperado's Lycoming but not by much. Don't forget that all the stuff you collected from the filter has gone through the oil pump. It wasn't designed to pump metal like that. I sure hope you come out OK on this. jrh

I will let yall know what the analysis results are when I get them back in a few days, probably by the middle of next week. It is only pure speculation at this point, but it was told to me by an old man who has rebuilt numerous engines over the years who looked closely at the metal flakes, that it looked to him like the flakes were probably chrome that came off of the rings, that the new rings were probably installed incorrectly and possibly even upside down by the guy who put them in, and that would contribute as to why it was blowing so much oil out. He said when clean oil is darkened that much in 30 minutes it is because of excessive blow-by, probably in all four cylinders, especially since all the plugs were oil-wet after the new top end was installed and they were all pink before the top overhaul. There was no significant amount of flakes in the screen before the top overhaul. The stuff looks like chrome plated glitter. The cylinders are steel, and the rings are chrome. He said it was just speculation on his part and nothing more. He also said if all the plugs were wet with oil it was because a lot of oil was getting past the rings. So I don't know. As soon as I get the lab results back I will know exactly what this stuff is and where it came from. Til then, everything is just that, speculation, until then.....

And???