I have a supertigre 90 that is about at the end of the break in stage. Just less than a gallon through it. I have only flown it for a summer. (very sparingly since it still has less than a gallon) I put it in the basement for the winter and I got it out today. I took off the carb to adjust something outside the cowl, and you can clearly see a redish splotch on the forward crank shaft. [:@] It is not raised or rough, but I was surprised to find rust already. I try to take care of my engines, and I usually put a little piece of paper towel in the carb to keep air out.
I dont think it will make a bit of difference, but I was kinda surprised. What can I do to prevent this in the future? I'm running recommended prop and fuel.
Also, the baffle somehow came lose inside the muffler. This is a one piece unit! It rattles at idle. There is no crash damage, not even a nose over yet. Is there any fix for this?

After run oil?

Be sure to run the engine dry after a flying session, use a fuel with a castor blend oil, and add after run oil before putting it away.

Just squirting the A/R oil in and flipping the engine a couple times isn't really enough - douse it well and then spin it a bit with your starter to be sure the oil goes all through the inside of the engine.

Bill.

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I put so much air tool oil in my engines that I must remove the glow plug, put a rag over the hole and hit it with the starter to clear it, when it is time to fly.

There is no reason to put your good glow plug through all of this. It could lead to a mangled coil. Not good.

Remove the baffle...

Go through the muffler outlet with a steel rod and a hammer. Callapse the baffle and push it up into the front of the muffler. Fold it enough you can pull it out the inlet hole with needle nose pliers.

With a ST90, you'll never miss the baffle.

Enjoy,

Jim

If you bore a cylinder block, or turn brake rotor/drums, then rinse them with water, as soon as they dry there will be
orange spots where the drops were. Ferrous Oxide! Those parts are cast iron, but the same happens to machined steel. Add
methanol to the equation and the problem is exasperated. As WR said, remove as much fuel as possible, and oil generously. If the engine is off the plane, seal in a ziplock baggy. No matter how dry your house is, that alcohol will suck the moisture right out of the air and into your engine. Ross

Are you sure its rust? Rust has a rough surface. You are probably looking at a stain from the castor oil and red dyed synthetic oil.

Yes, the piston ring are of cast iron, not in other parts as ballbearing, crankshaft and wristpin who are made of hardened steel. All parts will be rusted without after run oil...

Jens Eirik

What about you guys, using more castor ratio fuels?Do you have such rusting problems too?Pls. share your experiences.

One of the advantages that a controlline flyer has is that he uses a castor based fuel and his flight is over when the last drop of fuel is consumed by the motor. That said we still use a good after run oil. I haven't seen a speck of rust in a motor of mine in at least 35 years. This is both C/L and R/C.
Make sure you run them dry and oil them well. Also correct about bagging them if off the plane, but immersion in a bucket of kerosene is still the best anti rust method known to us.
Dennis

Words of wisdom Dennis. Works for me too.

Castor 1 - Rust 0

Methanol attracts water, and thus causes metal parts to corrode.
To be sure to run all methanol out of the engine, I used zippo lighter fuel (naphta), mixed with automatic transmission oil (AKA after run) in a 50/50 mix. At the end of the day, clamp off the fuel line, and run a few squirts of this mixture at high idle whilst keeping the plug lit.
This removes most of the methanol and acid combustion by-products from the engine. At the same time, all parts are covered with the highly acid buffered tranny oil to neutralize any combustion products left, and prevent rust.
Engine outside is cleaned with tissue and WD40, which also leaves a corrosion protecting film when dry.

I've always used only all castor and have never seen any rust or had to change a bearing. To be honest, I'd never known an engine could rust until I started reading forums like this. Most of my flying, starting over 40 years ago, has been with CL and when I read about the rusting problems in RC I figured the only real difference was the way they shut down after a flight so I've always treated my RC engines the same way...full throttle and take off/pinch the fuel line.

If you keep your plane in the baement that is a very damp place usually therefore making rusting easier. Run dry of fuel leave carb open and squirt at least a teaspoon of automatic transmision fluid in carb turn pane on noise and spin prop by hand to alow oil to coat bearings. And as Bill said spin with starter to disperse oil.

I dont run the engine dry and I dont use after run oil or anything else but I use castor oil in my fuel. Just make sure you storage your airplane with the propeller pointing up to the ceilling so the remaining fuel in the crankcase runs down to the backplane where it wont hurt anything. Open the carburetor slightly so the mathanol can dry out and evaporate. I think the after run oils are only neccesary for long time storage.

I think everybody is missing the fact that he said the spot is not rough. It is most likely a castor oil stain. Mixed with the red synthetic oil those stains can look like rust.

If he doesen't know the difference form a stain and rust we could be waisting out time anyway.

Happened to me with a ST G51 after a crash about 6 years back.

I was so P-----ed off after the crash I just chucked the model on the shelf for a week without draining the motor properly and when I went to start the repairs, found rust EVERYWHERE inside the engine.

The Piston ring was seized with rust, the bearings were covered with it and there was a rust "sheen" all over the liner and crankshaft. And I was using 20% castor oil in my fuel.

Had to rebuild the motor entirely. (This was in the days when ST's were made in Italy and were a lost costlier than they are now. Nowdays it would not be economically worth doing a complete rebuild.)

It taught me a valuable lesson and I have been using After Run oil religiously ever since, whether the motor be Ringed, ABC, 2 or 4 stroke.

The only rebuilds I have done since that incident, have been as a result of crash damage or engines that are just plain worn out.

After Run oil is good insurance.

They can look the same, hard to tell till you scrape it. I have seen plenty of oil stains mistaken for rust.

Sport is right, and BuzzingB is onto something as well.