Cylinder Corrosion

[Guest]

Pull the rocker covers, if they are full of corrosion (assuming they aren't new stainless steel) there is a good chance that the inside of the engine has corrosion too.

Clarence

[DaV8or]

I say change the oil every 25 hours and check for metal. Run that sucker till you can't stand the oil consumption. Oil is cheap compared to overhaul. Those pitted cylinders aren't going to cause your engine to stop running. As to what else might be rusty, your oil filter will tell you when it's time to open it up, or overhaul.

[cujet]

Matt, I operate a small fleet of Lycoming powered aircraft. The cylinder corrosion/pitting you see is actually quite normal here in South Florida (It's often very humid here) .  Your pictures are obviously quite magnified, so the pitting looks worse than it is. Next time you have the plugs out, simply look inside with your eyes and compare what you see with the borescope pics. I think you what you observe visually will be quite minor in nature. 

 

You can use a tiny light on a stick, placed down the spark plug hole to get a good view. Or even the borescope light. 

 

At 5 hours/quart, your pitting is nowhere near causing a operational problem. In rough numbers, Lycoming allows about 3/4 quart per hour for a 200HP engine. Once you reach 4 quarts in 5 hours, it's high time to fix the problem. 

 

http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201427C%20%2812-29-2010%29/Lycoming%20Reciprocating%20engine%20Break-In%20and%20Oil%20Consumption.pdf

 

I've had success with CamGuard completely preventing cylinder bore corrosion. I really had trouble with our infrequently flown Extra 300L's engines and bore corrosion. However since using CamGuard, I've not seen any bore corrosion at all. 

 

If you look carefully in this bore, you will see what I mean. There are some small scores and some small pits. I overhauled the cylinder, honed it and placed it back in service. 

 

 

[mattbucy]

Thanks for the input, everyone. Glad to know the pitting isn't unusual. She runs smoothly and with plenty of power but since she's new to me I'm curious. I started using CamGuard a couple months ago. I figure it'll at least arrest further corrosion. Cujet: nice job on that cylinder. Wish mine looked so pretty!