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New Engine Break-in: flakes in oil filter

L

lr172

Well Known Member
my O-320 now has about two hours on it. I cut the oil filter and found some metal flakes. They look to be about .001" in size. I have 60's vintage steel cylinders with cast iron rings. The boring and honing was done 20 years ago, so a course hone, not the finer hones used today. These flakes seem normal to me for an initial break in run on a course honed engine. My partner thinks they may be too big.

Looking for an opinion from an expert. Hopefully this picture helps.

snp0zs.jpg


Thanks for your assistance.

Larry
 
Just realized this is really bad picture. The flash is reflecting off the oil and it looks like metal. Most of the metal can't be seen without light magnification.
 
Larry, a little more about the history of the engine would be helpful. Was it overhauled, or has it been pickled for 20 yrs? Does it have a new oil cooler and hoses?

Freshly honed cylinders are to be washed with hot soapy water then oiled. This takes off the particles of cut metal. Other metal particles from machining operations find their way into the engine. A manufacturing operation has wash tanks with micron filters to clean the parts before assembly. Other shops typically don't. A little fuzz is typical in a new engine but should be gone after the first couple of oil changes. This is one reason the oil filter is replaced after the first 10 hours. (2hrs or 10hrs, not much difference if the debris is just washed off the interior) It might take three changes to completely clean the engine, if debris is the source.

You can take a magnet and sweep under the filter paper and see if it makes the particles stand up, salute and sparkle. If so, it is ferrous.
 
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Thanks Bill. I overhauled engine. Cylinders were done 20 years ago by Harrison, case was done by ECI. I did not wash the cylinders, only cleaned with solvents until towels were not showing grey. I did not clean the case after ECI's work as I trusted they flushed it good (maybe not a good idea). New cooler, hoses, etc. I could not get any of the flakes to stick to a magnet, so suspecting aluminum. The oil pump is stock, but it has new gears.

I took the filter to an old A&P and he wasn't very concerned. He suggested checking the filter again at 10 hours to confirm particle quantity was decreasing.

I was not concerned with eminent destruction, but my QP wouldn't do a second flight with me unless I got an expert opinion.

Larry
 
It is common to see long, thin, curved aluminum shavings in the oil screen that are the result of the old style aluminum piston plugs wearing.
 
Drift....IF.....I use any towel on and engine build, (usually just compressed air) I will use paper towels, the micro fibers will break down and flush out easier than a chunk of cotton strand. :D
 
lr172 said:
Thanks Bill. I overhauled engine. Cylinders were done 20 years ago by Harrison, case was done by ECI. I did not wash the cylinders, only cleaned with solvents until towels were not showing grey. I did not clean the case after ECI's work as I trusted they flushed it good (maybe not a good idea). New cooler, hoses, etc. I could not get any of the flakes to stick to a magnet, so suspecting aluminum. The oil pump is stock, but it has new gears.

I took the filter to an old A&P and he wasn't very concerned. He suggested checking the filter again at 10 hours to confirm particle quantity was decreasing.

I was not concerned with eminent destruction, but my QP wouldn't do a second flight with me unless I got an expert opinion.

Larry
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You should be ok, but there is no definitive way to know. Just double your hours, then take off the filter and check again. With all the new oil supply stuff, at least you aren't getting any residual flakes downstream of the filter to damage bearings.

To Mikes post - we assume there is no ridge in the bores now, and what design style pin plugs do you have?

Bret - +1 - use hot tide and a bristle brush, ready to wash down with hot distilled water, blow dry, and add oil quickly.
 
BillL said:
You should be ok, but there is no definitive way to know. Just double your hours, then take off the filter and check again. With all the new oil supply stuff, at least you aren't getting any residual flakes downstream of the filter to damage bearings.

To Mikes post - we assume there is no ridge in the bores now, and what design style pin plugs do you have?
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Std. pins with alum caps. they had very little wear from first 2000 hours and I re-used them. One of the pins had slight corrossion so I replaced it with a newer style pin with built in ends.

Larry
 
lr172 said:
Std. pins with alum caps. they had very little wear from first 2000 hours and I re-used them. One of the pins had slight corrosion so I replaced it with a newer style pin with built in ends.

Larry
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Problem,....... Can't mix pins with out replacing the opposing cylinder pin. These should all be up-graded to Heavy wall and your choice of plug end or the superior type with plug ends built in. Did you weigh your pistons to see how close a match they are? Most case shops leave the oil galley plugs out for you to clean before assembly
RHill
 
rhill said:
Problem,....... Can't mix pins with out replacing the opposing cylinder pin. These should all be up-graded to Heavy wall and your choice of plug end or the superior type with plug ends built in. Did you weigh your pistons to see how close a match they are? Most case shops leave the oil galley plugs out for you to clean before assembly
RHill
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My rods were balanced by the shop, but I did not weigh the pistons. My pins are all heavy wall pins. ECI told me that the new pins were matched weight to the old pins. After installing the engine I wished I had weighed them. How critical is it to replace the opposing pin?

Larry
 
lr172 said:
My rods were balanced by the shop, but I did not weigh the pistons. My pins are all heavy wall pins. ECI told me that the new pins were matched weight to the old pins. After installing the engine I wished I had weighed them. How critical is it to replace the opposing pin?

Larry
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Unless you have a balance issue,I'd forget about it.This was from a yellow tag included in my piston box's. Same with the aluminum in the filter,change the filter out early and see what you have.If it ain't broke don't fix it! Down the road you can pull the plugs and scope the cylinders to see if there is any scoring,easy enough to do.
RHill
 
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rhill said:
Unless you have a balance issue,I'd forget about it.This was from a yellow tag included in my piston box's. Same with the aluminum in the filter,change the filter out early and see what you have.If it ain't broke don't fix it! Down the road you can pull the plugs and scope the cylinders to see if there is any scoring,easy enough to do.
RHill
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I should feel it if I have a balance issue, correct? I suspect the engine can't pull itself apart without feeling something, correct? I wouldn't say my engine is a smooth as a swiss watch, but I don't feel anything out of the ordinary. I will pay closer attention on the next run.

I did not document which cylinder got the new pin, so I would likely have to pull 3-4 cylinders to replace the opposing pin. That means most of the baffling has to come off :mad: I found the SI from Superior, they indicate the weight issue with interchanging, but they don't document the weight difference. If it is only a few grams, I figure it will fall under the tolerances for out of balance rods. Given that my rods were balanced, I should have some room for some weight offset margin. I will call superior tomorrow.

Larry
 
Perhaps another point of view - it isn't especially alarming that a freshly assembled engine will generate some aluminum, and it's very possible that it's the piston pin plugs. But it may not be. Sorry to say, but there are many other potential issues. So, I'd recommend that you just follow the guidance of the service letter (earlier post) and not assume the source.

If, with a little more time, the metal stops showing up in the filter, then I'd leave it alone. I definitely would not pull a jug to replace a piston pin plug. (If somewhere down the line it has to come off, that's another story.)

There are so many reasons that there could be balance issues that it might be easier to take it to a shop that does prop balancing once you get past the question of where the metal is coming from.

YMMV

Dan
 
rHill may have figured out my shavings issue. My block came back shiney clean from ECI with the gallery plugs out (it had clearly been "hot tanked" as all of the paint was gone). This was my first aircraft rebuild, but have done many auto engines. Auto machine shops (performance shops anyways) fully clean the blocks after machining and the rebuilder doesn't need to clean out the galleries. Though they don't install the gallery plugs for you. I foolishly followed that convention and didn't think to clean out the galleries. If aviation shops don't clean them, that would explain the alum. flakes.

Either way, I will cut another filter at 10 hours. As long as the quantity of metallic debris is on the decline, I'll just keeping pulling filters every 10 hours until comfortable that it has stopped.

Thanks for all of the guidance here.

Larry
 
DanBaier said:
I definitely would not pull a jug to replace a piston pin plug. (If somewhere down the line it has to come off, that's another story.)

Dan
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I was only considering pulling the jugs to replace the pin / plugs due to the weight difference. My current thinking is that there is not enough difference in weight to cause serious issues. Tomorrow I will call superior to find out the actual weight difference and see if I can find out an acceptable tolerance. Because my rods were balanced, I should have a pretty good margin to work with. I don't know what to expect from the piston weights though. They did not list weights on them like performance auto pistons (sold in weight matched sets), but I suspect they run them relatively tight in tolerance.

Larry
 
lr172 said:
I was only considering pulling the jugs to replace the pin / plugs due to the weight difference. My current thinking is that there is not enough difference in weight to cause serious issues. Tomorrow I will call superior to find out the actual weight difference and see if I can find out an acceptable tolerance. Because my rods were balanced, I should have a pretty good margin to work with. I don't know what to expect from the piston weights though. They did not list weights on them like performance auto pistons (sold in weight matched sets), but I suspect they run them relatively tight in tolerance.

Larry
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Good course of action. I wouldn't get all worked up over a little weight difference. If it is within factory weight class, then fly on. The engine certainly won't know it. You probably won't either.
 
Prop ballance

The new Dyna Vibe will pick up prop and crank unbalance.Sometimes you wont feel vibration that the tool will pick up. It's money well spent,have the prop balanced,it will put your mind at ease,any weight difference,will as you noted, be small,pulling the engine apart at this point will do more damage then good.One final note,along with the filter change,pull the finger screen at the back of the sump.
RHill
 
rhill said:
The new Dyna Vibe will pick up prop and crank unbalance.Sometimes you wont feel vibration that the tool will pick up. It's money well spent,have the prop balanced,it will put your mind at ease,any weight difference,will as you noted, be small,pulling the engine apart at this point will do more damage then good.One final note,along with the filter change,pull the finger screen at the back of the sump.
RHill
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Good idea. I figured that I would change the oil and clean the screen at the 10 hour change to get any flakes out of the oil and pan as best I can.

Larry
 
rhill said:
The new Dyna Vibe will pick up prop and crank unbalance.Sometimes you wont feel vibration that the tool will pick up. It's money well spent,have the prop balanced,it will put your mind at ease,any weight difference,will as you noted, be small,pulling the engine apart at this point will do more damage then good.One final note,along with the filter change,pull the finger screen at the back of the sump.
RHill
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Doesn't the accelerometer mount to measure the vertical acceleration? That would not get a piston/pin balance issue, those forces are lateral, and secondary forces.
 
D

BillL said:
Doesn't the accelerometer mount to measure the vertical acceleration? That would not get a piston/pin balance issue, those forces are lateral, and secondary forces.
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I'll reread the info and report back.My Understanding the new unit will do a lot more then the first gen. They call it full spectrum. Link to a case study on a Kit Fox, http://www.rpxtech.com/documents/Rotax 912 Carb Case Study 1.pdf and http://www.rpxtech.com/DynaVibeGX2.html
RHill

Link to YouTube Video more on engine balancing, https://youtu.be/46H8wJ64Gis
 
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Changing horses mid stream

Well...it could have been worse. The Op didn't flush the case before assembly and has one miss matched wrist pin, not technicality correct but its done,installed with baffling,and flying. Changing the filter and cleaning the intake screen every 10 hours is a lot less expensive then taking it all apart to correct issues that may not exist(if it ain't broke,don't fix it!). Everybody should have there prop balanced at least once.It's proven time and again to be beneficial in every case. In this case it could demonstrate the need for action or confirm none is needed. Sorry for the drift,but still on point.
RHill
 
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