Borescoped My Cylinders, High Blow by and Oil Consumption

[Rotorhead]

Well, while you're here check out my cylinders I just borescoped and let me know what your thoughts are. I'm doing this primarily because I've been experiencing higher oil consumption in the past +6 months of 1qt/3hrs. (Yikes) Only fill it to about 6qts and tend to change oil every 25-30hrs. No metal in the filter in the past 3 changes and oil analysis comes back normal for my 1430hr engine.  I've also had abnormally high oil temps with low to normal CHT's. (Granted I live in ABQ but never seen oil nearly red line before). My initial thoughts are increased blow by due to frozen or broken oil rings hence the oil use/ higher temps. I just completed the oil control ring flush yesterday but haven't ran it yet. 

So, check out the pictures in the linked albums and let me know what your thoughts are. I believe I see a good amount of lead deposits on some of the cylinders and oil pulling as well. Below are the bottom spark plugs for reference too. Nothing crazy or out of the usual for residual oil from my perspective. 

https://photos.app.goo.gl/p4o59zXnJ8sN8smbA

https://photos.app.goo.gl/wdjMyvKrDWE2V5wA6

https://photos.app.goo.gl/AXtSkn4HXR5t8Atr9

https://photos.app.goo.gl/pAVCbk2QWQgWpvoF9

In the meantime, I'm trying to pull the vernetherm to test if it's working correctly but it's being a real PITA. The return line from the oil cooler is getting in the way so seems like I'll have to pull that as well. I'm also trying to re-install the oil regulator so the bypass holes line up correctly but will need a new crush washer for that. (Mines the non-adjustable kinda adjustable with washer type.)

Let me know what youses think!

-KC

Edited June 23, 2022 by Rotorhead

[A64Pilot]

I think from what I can see is that you have some bore polishing and pitting in one photo

I concur high oil temp is from blow by and a compression test should confirm it.

Let’s us know if the flush does anything much and how long it lasts.

How many years for those 1400 hours?

Kept inside or outside for those years, all in New Mexico?

There may be nothing wrong with your rings, the issue could be the cylinders.

If it’s bore polishing, wear greatly accelerates due to lack of lubrication, usually you see high iron in an oil analysis.

 

Oil regulator holes lining up? I don’t understand.

[Rotorhead]

@A64Pilot I agree with some of the polishing. I wish the borescope had better resolution but it is what it is. In some pictures cross-hatching is still very evident at least on one of the cylinders. 

I believe it's been since 2007 since the MOH. It's been around the country but primarily in North Dakota until recently and in a climate controlled hangar at that. Same thing for here in ABQ. 

Oil Px regulator such as how 211 posted about. I don't have any pictures but I have the same issue where the holes aren't lining up. Is that on purpose..??

 

[Rotorhead]

Anyone see any issues with my vernatherm? There's a line on the top conical part but it is not grooved or etched, just appears to be rubbing. Appears to be working correctly, extends at 178° but I didn't take measurements. 

Edited June 24, 2022 by Rotorhead

[Shadrach]

Hard to tell. Very little cross hatch visible on most cylinders but that could be a function of the image quality The one with most visible crosshatch (#3) looks like it might have some scuffing. 

 

[MBDiagMan]

So. Is it safe to assume that this engine is holding good oil pressure?  If so, then you’re golden.  Cylinders are just accessories on an aircraft engine much like an alternator or vacuum pump.  If the bottom end is not making metal, is holding good oil pressure and no signs of corrosion on lifters, then it is well worth replacing cylinders.

As long as it is a repair that can be done without splitting the case, you’re in the money.

[Rotorhead]

No real gain or loss on after doing the ring flush. It seemed like only #2 had a hydrolock that I could work through. Oil consumption still seems to be on par as before and oil temps may be *slightly* lower. 

Next move I believe is taking #2 cylinder first off and looking inside. See if cross hatching is still present and putting a new hone/ rings on. 

When replacing rings, after inspection is it typical just to replace all while in there or IRAN??

Edited July 30, 2022 by Rotorhead

[Jsno]

I overhauled an O-360 installed new steel cylinders but unfortunately did very little flying the first year.  As a result the fresh cylinders got some rust and pitting in them.  I pulled them and cleaned them up and installed new rings,  And they rusted again.  I think that the problem is that the pitting was not fully removed when I honed the cylinders and the corrosion just started from the pits that were not removed fully. The only good way to remove pitting is to have the cylinders ground.  My oil was turning black after about 15 hours and consumption was up.  When I scoped the cylinders they looked like yours, the rust particles had scuffed the cylinder walls. 

I pulled them and sent them to Aircraft Cylinders of America and had them Nickel Plated.  Cost just under 2 K.  When I got them back I ran them in and they seated in under an hour.  Very pleased with the results.  No oil consumption and no pitting worries.

I once bought a dry climate engine only to find that it had corrosion.  Doesn't matter so much about thee atmosphere humidity as much as how much moisture is in the engine when it is sitting idle. That will be the start of your problems.  High moisture is usually caused by short flights or ground run ups.

As many hours as there are on that engine SMOH, I would top it with some overhauled Nickel plate cylinders as new cylinders are hard to find now.  BE sure to use new exhaust valves.  When you pull the cylinders you will be able to inspect the cam and lifters for pitting.  If any found you will need a new cam and lifters as they do not heal themselves. 

[Rotorhead]

@Jsno Appreciate the insight, gonna take the cylinders off and see what we're really looking at. What was the turn around time on plating the cylinders??

Bad experience after not replacing the exhaust valves or something??

[Will.iam]

14 hours ago, Jsno said:

…  Doesn't matter so much about thee atmosphere humidity as much as how much moisture is in the engine when it is sitting idle. That will be the start of your problems.  High moisture is usually caused by short flights or ground run ups…

That is the main reason i bought a portable dehumidifier. I connect it to the oil filler tube and you literally see steam come out of the breather tube for the first minute or so. I leave it running and in the summer a shop fan blowing on the cowl inlets to help cool down the engine and not just heat soak while i clean off the bugs and clean the bottom from soot and oil. After I’m done about 45 mins later or so i turn off the fan and dehumidifier and close up the oil filler tube. I have cam guard in my oil and fly my plane at least once every 2 weeks. If i know i will be going over that sit limit i will connect the dehumidifier and have it pull the humidity down to 28% then it cuts off if it’s very humid outside like raining, you can see the sensor i have placed in the oil filler tube rise up within minutes to 45% at which time the dehumidifier cycles again. Seems to be the best trade off of not running continuously and not having humidity go too high.  
this is the one i bought and use. 
Vacplus 4,000 Sq. Ft. Dehumidifier 60 Pints Dehumidifier with Drain Hose with Effortless Humidity Control with Universal Wheels for Home Medium Spaces and Basements (Nickname: VA-D1909) https://a.co/d/hK8z23y

[Fly Boomer]

3 hours ago, Will.iam said:

portable dehumidifier. I connect it to the oil filler tube

How do you connect this room dehumidifier to your engine?

[Will.iam]

The shipping styrofoam makes a great sealed top that i cut out and attached some home depot a/c duct work to it to a reducer of 3”. Ill have to go over and take a picture which will describe it better than i can in words. Neigbohrs that come over and see it for the first time say what the hell is that. Once i describe it there are generally two responses either I’m going to have to get me one of those or I’ve been doing it my way for xx years and It’s worked for me so far. Really i have no way of testing how beneficial This is for my engine since i have no control group engine to compare it to but based on the exhaust valve bare, and an exhaust valve dipped in straight oil, AS 15w-50, exon elite, and phillips 20w-50 with camguard, the exon elite went the longest before rusting 21 days IIRC followed shortly by cam guard with the bare valve rusting day one. But they also had a bare valve in a humidity controlled box and after a month with no rust terminated the test. So i try to limit damage with the dehumidifier after 14 days. My engine was already at 1600 hours when i bought it so I’m just trying to minimize any additional damage until i do an OH. 

[Fly Boomer]

2 minutes ago, Will.iam said:

shipping styrofoam makes a great sealed top that i cut out and attached some home depot a/c duct

Nice!

[Will.iam]

The power strip is a humidifier controller.

WILLHI 1803-H Humidistat Digital... https://www.amazon.com/dp/B07VNFM94W?ref=ppx_pop_mob_ap_share

By putting the sensor down into the oil filler tube i have a feedback loop to control the humidity in the engine. The dehumidifier itself has a sensor but you would need to inclose it in an airtight box or room. When i had my fuel pump and throttlebody / servo overhauled it was a 6 week lead time so i plastic wrapped the engine with the dehumidifier inside the wrap and it kept the whole engine at 30%. It would rise slowly as I couldn’t seal around the front wheel and wheel well very well nor the step latter i had put the dehumidifier on but it worked well enough that i didn’t have to mess with pickling the engine. I had also drained the oil out the day before but was surprised at all the oil in the bottom of the wrap plastic when i pulled it off 6 weeks later due to residual oil still dripping out of the oil drain and where the oil filter was  removed.

[Will.iam]

Here are pictures of the wrap. Looks like a spider’s cocoon but gives you the idea better than me trying to describe it. 

[Mufflerbearing]

I have found that by just opening the oil filler when the engine is hot, lets out all of the steam.  Simple and works.

[Rotorhead]

^^ Same. Kinda cool to watch when you do it after landing in -30*F air temp.

BTW, anyone happen to check out my post above about the vernatherm line?? 

[Jsno]

14 hours ago, Rotorhead said:

@Jsno Appreciate the insight, gonna take the cylinders off and see what we're really looking at. What was the turn around time on plating the cylinders??

Bad experience after not replacing the exhaust valves or something??

Turn around was three weeks.  Lycoming exhaust valves work harden.

Quote from Sky Ranch Engine Manual, "The exhaust valve face and seat work hardens in service.  A work hardened exhaust valve is more likely to fail because of fatigue.  Also for two surfaces to form a gas tight seal, the surfaces must be elastic to conform to each other. A work hardened valve and seat face will have lost their elasticity and be more prone to valve leakage than a new valve and seat.  For this reason, used exhaust valves and seats are not as desirable as new regardless of appearance."

One of my valves was cracked and the edges were ground down sharp enough to shave with.  Obviously had been through more than one cycle of overhaul.  New valves are twice the cost of used but I think that they are worth the assurance that they won't fail.

[Rotorhead]

Took a small plunge today and took #2 cylinder off. Have a great A&P of +57years experience to help and educate as we go along. Here's some piston pictures but I completely forgot to get the inside of the cylinder before he took it away. Needless to say, it was completely glazed over, very smooth with a definite line of where the piston stroke is. He's taking a dingle berry hone to it to de-glaze and get that cross hatching back.

Going to be cleaning the piston as well. You can definitely see the carbon buildup and oily color on top too. 

The rings definitely had their fair share of carbon buildup too. New rings have been ordered and hopefully going to throw it back together sometime this week. 

[N201MKTurbo]

You should read the piston cleaning procedure in the overhaul manual. It is very specific about how to do it. If you do it according to the manual it is tedious, but will not damage the piston and you will eventually get it squeaky clean. 
 

For full disclosure, I’ve never cleaned a Lycoming piston by the book, but I have done Continental pistons by the book. The only tool allowed in the ring groves is a piece of string. I did them in the kitchen sink with a nylon cord tied to the faucet. You loop it around the piston in the groove and move the piston fore and aft along the cord. I used comet cleanser (limestone dust) as the cleaner. It got everything out without removing any metal.

[Rotorhead]

6 minutes ago, N201MKTurbo said:

You should read the piston cleaning procedure in the overhaul manual. It is very specific about how to do it. If you do it according to the manual it is tedious, but will not damage the piston and you will eventually get it squeaky clean. 
 

For full disclosure, I’ve never cleaned a Lycoming piston by the book, but I have done Continental pistons by the book. The only tool allowed in the ring groves is a piece of string. I did them in the kitchen sink with a nylon cord tied to the faucet. You loop it around the piston in the groove and move the piston fore and aft along the cord. I used comet cleanser (limestone dust) as the cleaner. It got everything out without removing any metal.

Nice, appreciate the intel! 

Hope Tempe is good, I miss being out there...go Devils.

-KC

[N201MKTurbo]

1 hour ago, Rotorhead said:

Nice, appreciate the intel! 

Hope Tempe is good, I miss being out there...go Devils.

-KC

Where are you now?