I decided to take off the backplate of my os 46 la so I could put some RTV on it, when I took it off to my surprise rust inside of the engine right where the piston arm connects to the shaft[X(], the engine has 3 or 5 tanks of fuel, I dont use run after oil, am I already seeing the effects?[]

Could be. How long between those 3 - 5 tanks? Do you run the engine dry at the end of the day? What fuel are you using? I know, so many questions.
Paul

I've never seen rust at the connecting rod / crankpin on any engine. I've seen tin bearing retainers, wire wrist pin keepers and crankshaft counterweights get pretty funky. Of course the old iron piston, steel liner engines were very rust prone.

Are you sure it's rust or could it be rust colored stains and crud from oil and combustion? I've taken apart engines and found brownish or rust colored stains that were not a problem at all. The only thing that can rust would really be the crankshaft and a few other steel/iron parts that combatpigg mentioned. The other pieces are generally aluminum, bronze and other materials. Of course aluminum and other metals can also corrode in their own way.

Does the engine turn over smoothly and run well? If so, it may be no big deal.

I've never bothered with after run oils. Usually my last flight of the day is done with a dead stick landing and there should be enough of a castor oil film inside the engine to take care of the rest. Real finicky guys will run their engines on 0% nitro fuel at the end of the day to flush out the nitro. The idea is to postpone pitted bearings.

All you have to do is put acouple of drops of coolpower or klotz oil down the carby after flying andturn it over a few time to protect the motor. Also a good idea to run the fuel out of the engine at the end of the day ie drain any fuel from the tank and then start engine up like normal, should run for a few seconds and then splutter out. Is a good idea

There are no bearings on an LA to rust. The piston is aluminum, brass, and nickel. The only part that's iron is the crankshaft, and maybe the connecting rod. The crankshaft is supported by bushings. As long as you don't run it lean and burn the oil, there's very little to go bad. Run the fuel out at the end of the day, and you shouldn't have any problem. My guess is you're mistaking combustion byproducts and breakin wear for rust. Put it back together and go fly.

Brad

Running 0% Nitro at the end of the day would not help in my opinion. Methanol is hydroscopic as well (picks up moisture) and there is typically 60-80% Methanol in all glow fuels. Methanol is the main culprit in rusting the bearing.

Hi!
The only thing that could rust in an OS LA engine is the crank-shaft and the piston bolt.

Every tank has a week in between I fly every sun.I tried to stick a piece of paper towel to get off but no use, I dont know the name of the part but its the big round thing, first thing you see when you take the backplate off, looks like a counterweight, that was the only thing with this rust looking stuff on it, I'm using wildcat 15%, I run a lil rich since the engine can run off of fuel iwith castor oil but I have to run a lil richer than normal

Flyboy:

Nothing to worry about if you use the pink fuel with castor oil in it; which is the only one I would use for flat bearings.

Seal the back plate, put some thread Loctite on the bolts, and get ready for next Sunday.

Congratulations on your solo!

Regards!

sorry, I was thinking of castor, its the orange 15% 18%syntheitc, cant spell, if I read right my eninge can run off of fuel with synthetic but have to run a lil rich sorry for the mistake, thanks my solo was cut short cause the backplate was comin loose that why I was putting RTV on it

It sounds like you are talking about the crankshaft and some of them are in fact counterbalanced. Whether it is actually rust there or stains form other stuff, it likely is no big deal. I'd run it and have fun.

From the sound of it, it probably is rust. It's always a good idea to run the engine dry at the end of the day. That gets most of the alcohol out. As others have said, that engine doesn't have ball bearings, and about the only thing in it to rust is the crankshaft. A little rust won't hurt. Just go fly and have fun.
Paul

If I am storing an engine for while, I'll drop some automatic transmission fluid directly in the carb (5-6 good drops) and turn it over slowly by hand a few times. The high levels of detergent in the tranny fluid does wonders clearing up the film that tends to build up in these from the oil residue.

thanks a lot, I was getting worried a bit, so tonight I'll just put some RTV on the backplate and get a bottle of ATF to prevent rust,