Migration Situation??

[Magman]

Lycoming O-235 L2C. Currently has about 350 hrs and 7 years SMOH by a Major shop.

It began with slightly elevated aluminum in the oil sample. Then iron went up a little too. Oil analysis folks felt there was no reason for concern. Yet. Compressions have been good and power and oil consumption were normal. Baffles were tight and temps were fine.

A few tiny flakes of AL were found in the screen. It appears the number and duration of flights decreased about this time. At the last filter pull the jugs were scoped. #3 had a slight marking in the Piston Pin range. Although it would have been “ Lycoming Legal “ to fly the decision was made to pull #3. Another Piston Pin Plug issue was expected.

The Plugs ( end caps) appear to be fine as the dark ring indicates normal wear to me.
With the cylinder off the marking is almost indistinguishable and cannot be felt. So what is the source?

The Piston Pin did not want to move in the Piston. In the removal process one of the Plugs was scratched. Some scoring was noted on the Piston and Jug about 90 degrees from the Pin travel range. We believe this to be the source of the metal. The marking on the cylinder can only be felt in one spot. So what happened here?

The owner mentioned he had a Spark Plug issue some time ago. A chunk of the Insulator of the REM37BY plug had broken off in #4 cylinder. It was never found. The Spark Plug was replaced and everything seemed fine. Back to current and he thinks that when the AL issues started. I have seen Exhaust Valves break and pieces found in another cylinder. Did the ceramic also “ Migrate” and then gouge #3?

My first try at attaching pix so I hope it works. There are some poor quality pix of the components.
Comments invited on:

Cylinder / Piston scoring
Blue Piston Pin
Pin tight in Piston
Deposits of side of piston

Comment on suggested path forward also.

Hmm. Doesn’t seem to load pix. I’ll post this and try again.

 

[Magman]

Hope this works!

 

[Gary Ward]

Does not look to have a really good ring seal. I do not see any taper on the face of the rings, look pretty wore out to me.
Wrong oil used? and wonder if Cam Guard was used?
Looks like it was put together dirty.
Pins were not properly fitted to piston?

Here is a 1789 hr piston out of my old 0-320. You can clearly see that the rings were sealed up. This pin was "seized" I couldn't push it out with my hand. I left it alone and put it back together and ran it. It sealed up great with even better leak down numbers. It got a good cleaning(the rings and pistons) and only lubed with WD40 when I put it back together. Often the wrong lube is used on the rings and they don't break in well.

Same piston, nothing wrong with it after 1700+ hrs.

 

[Kenny Phillips]

That discoloration on the wrist pin would have me concerned, as much as scoring on the piston.

 

[Gary Ward]

That discoloration on the wrist pin would have me concerned, as much as scoring on the piston.

For sure, I didn't even see that as I didn't scroll over to see it. Wow...

 

[PaulS]

Piston and cylinder at a minimum. I would want to know the crank bearings are good too.

 

[Dan Thomas]

Piston and cylinder at a minimum. I would want to know the crank bearings are good too.

Yup. Looks like it ran without oil for a bit. Got pretty hot. Perhaps a cold start with W100 oil?

 

[Gary Ward]

You have me confused? Why show pictures if they are not the subject matter?

sorry I don’t understand what you are asking?
Good luck with it.

 

[Magman]

I deleted second set of pix.

I am asking what caused this? Is the concern with 1 cylinder or more?

 

[Gary Ward]

So the engine is not apart yet? It is still running?

If so maybe keep running it and cut the filter often and do oil changes and analysis more often until it is is not running well or the metal numbers go up further.
Then start by taking the clys off and go from there.

Or skip all that and take it apart now and find out what is going on.
Why show a rusty wrist pin? That had to be sitting around for years, what is the point?

 

[Dan Thomas]

The O-235 has problems with running too cool, and moisture in the case results in cooler weather. It's much worse if the owner runs it up without flying it, and puts it away. I have found water droplets between the piston and cylinder walls in O-235s. Aluminum and steel together, with water as an electrolyte, and oil to contribute sulfur and chlorine and nitrogen, produces acids that eat the engine, pitting the cylinder walls so much that they wear faster and the bottom ring leaves a ridge at the bottom of its travel. That ridge shaves aluminum chips off the piston pin plugs. You find those chips in the filter, and iron from the wearing cylinder shows up on the oil analysis.

And that was in flight school airplanes. I finally blanked off the oil cooler year-round to minimize it. Oil temps never did get very high even in the summer on hot days. In a Citabria.

 

[Magman]

One cylinder is off now.

The point was that after many hours the pin was not blue.

 

[Jdm]

The owner mentioned he had a Spark Plug issue some time ago. A chunk of the Insulator of the REM37BY plug had broken off in #4 cylinder.

Apparently this is happening a LOT with Champion plugs lately!

 

[Dan Thomas]

Apparently this is happening a LOT with Champion plugs lately!

Might be a quality problem, but cracked insulators can happen when a mechanic isn't real careful when gapping, or when trying to open a gap that was closed too much. Any side force on the center electrode will damage that insulator.

From Champion's manual:

 

[Jdm]

Good point. I’ve never seen one damaged from gapping, but I guess if you go about it with a hammer or something maybe. I’ve always used the gap tool. Every shop I’ve worked in has had one. The guys at the mag overhaul shop I use tell me they’re seeing an incredible number of broken ceramic insulators on champion plugs. Some have caused other damage to the engine. It’s gotten to the point they are now advising customers not purchase the new champion plugs until quality control is addressed.

 

[Dan Thomas]

Good point. I’ve never seen one damaged from gapping, but I guess if you go about it with a hammer or something maybe. I’ve always used the gap tool. Every shop I’ve worked in has had one. The guys at the mag overhaul shop I use tell me they’re seeing an incredible number of broken ceramic insulators on champion plugs. Some have caused other damage to the engine. It’s gotten to the point they are now advising customers not purchase the new champion plugs until quality control is addressed.

Champion bought up Auburn, makers of the best aviation plugs ever, and shut them down. I wish they hsd shut down their own production and produced the Auburns, even if under the Champion name.

Maybe they're wishing that, too.

 

[Magman]

IIRC AC begat Auburn.

At least we know who to blame ; Albert Champion (AC) !

 

[Jdm]

Looks like you can still get old stock Auburn plugs on eBay.

 

[Magman]

Metallurgist A & P believes the Pin would have to be about 900 degrees F in order

to turn blue!

 

[Dan Thomas]

Metallurgist A & P believes the Pin would have to be about 900 degrees F in order

to turn blue!

Nope. Only 575°F.



I've used the colors for heat treating. Still do once in a while, when making some cutting tool. The colors up to 1000 are oxides. At 1100 we're talking about the steel as it starts glowing. To fix a drill bit that keeps breaking or goes dull real quick, you heat it until it glws a dull or medium red, and quench it in water or oil. Then clean off all the oxide so the steel is bright, then gently heat it until you get a light or dark straw color, and let it cool. Get it blue, and it will dull real quick again.