Hello Everybody,

I have some questions regarding the internal compositions of the engines. I have a OS .50 and a thunder tiger .46 engine. The OS engine was used less than 5 times and it was spoiled. The engine could not be left in an idle state because the is no more compression.

When I flip the propeller, it will not bounce back, instead, it will turn in the same direction. I opened up the engine crankcase and found that my ball bearings, crankshaft was very very rusty. Please advise me on any ideas to solve this. (eg: Any spare parts for the engine that I can change...)

For the thunder tiger, the same problem occurred. But for now, it still has compression, so it can still be used for the moment. But the crankshaft and ball bearings are also rusty. In some cases, when I stop the engine by closing the carburetor, the propeller would somehow seem to get stuck.

The OS Engine got rusty was maybe due to my crash landing. it landed into a pool of muddy water. However, my thunder tiger did not come into contact with any water but how in the world did it get rusty?

Does anyone have any solution to help me out? I will be very glad if someone will just post his comment(s).

Thanks a lot!

The OS engine is probably junk. The cost of replacement parts will be virtually as much as the price of a new motor. In the case of the TT, I suspect that you are leaving the engine for prolonged periods with fuel in the crankcase. Since you live in a area that suffers from high atmospheric humidity, the alcohol in the fuel absorbs water from the air, which is what is rusting your motor. If you use high nitro content fuels the problem is worse. Use an after-run oil to reduce thge liklihood of internal rusting. Automatic transmission fluid works very well as an after-run oil.

Most likely you are confusing the castor oil stains with rust. You cannot tell if bearings are rusted till you take them out and clean them. I wouldn't worry about it. As for the OS, have you made sure the head is tight?

It's hard to tell from here what's wrong with the engines.

Sport pilot is right that some oil residue can look like rust. But that doesn't mean you haven't rusted your engines either.

Engines with rusty bearings don't turn smoothly, there is resistance not related to compression, and the movement often feels jerky or "crunchy". If you are getting that kind of feel, you can repair the engine, but it may or may not be worth while depending on how bad it is. Often all you need to do is replace the bearings and maybe the crankshaft.

The OS .50, is it ringed or ABC? If it has a ring, then low compression when cold isn't necessarily the end of the world. However if rust is a problem the ring could have rusted, and the whole engine could be junk. If you flip it backwards, do you get better compression? For ringed engines, you often get better compression going backwards, and that's a good thing. (flipping backwards actually more closely simulates what is going on inside a ringed engine when running).

Your best bet is to find someone near you that has experience taking engines apart and fixing them.

If the engines have rusted, (and it sounds like they probibly did), then what britbrat said about preventing it in the future is correct. In the future, when you are done for the day, empty the tank, and then start the engine to quickly burn out any fuel left in the engine. Then put in a good shot of oil and flip the engine a few times to get the oil to travel all the way through the engine. It will go a long way towards keeping your engines from rusting up.

the .50 is ring..so it's not going to have a tight comprassion like ABC tapered cylinder
i wouldn't trun the engine anymore.
if there's rust on the shaft counter wiegth...most likey there's gunk build up
on the ball bearings..you need to break that up and flush it
to prevent scratched to the piston/sleeving and a possible leak to the front bearnings
in the future.
just take it apart and soak let it soak over night and flush it.
grease remover from $.99 store works for me.

it's only a single cylinder with 3 moving parts.
you took the back plate off already..
just take the head off..the sleeving should slide right out..
if not lube it as much as possiable. if needed,heat it to expand the casing
or use the back end of a tooth brush to push up the sleeving.

the rod disconnect from the shaft. take the piston/rod out.
the shaft should slide right out

lube the o ring on the carb to prevent it from drying or cracking

use blue loctite (not perminate) to prevent the screws from coming loose

seal the backplate, carb with rtv or something to prevent air leaks.

use after run oil.lol

How do you take the ball bearings inside the engine from the crank case? It is so tight!
The rod connecting the shaft and the crank case made me unable to take the piston and cracnk shaft apart.

Pls advise...

Thanks guys!

I hope you mean the crankshaft ... perhaps you need to remove the drive washer first, that is what holds the shaft on so tight. Or do you mean the connecting rod? You need to be clearer ...

As for the bearings you are best heating the engine up in an oven, once the casing is hot it will assist in removing the bearings. If your bearings are not bust leave them alone as you are not firmilar with removing them. You will have problems putting them back in again.

You need to disassemble the engine and polish the parts. Polish it with Autosol but DO NOT polish the inside of the liner and the outside of the piston. I polish my engines every 3 gallons. No point trying to polish your bearings!

When you remove the connecting rod please remember which side is the correct side when you assemble it back in. Bets to scratch an 'X' on the side that faces you.

Great advise above.. But you may want to get some help disassembling
your engine.. You do have to pull the piston to get it all apart.. And with
the rings if your not careful you could cause more problems, And you may
have to press the bearings out..But I'm not sure on that.. If the rust is
not the bad you may be able to just use solvent to clean it out without
taking it all apart then reoil really good.. Yeah after a misshap with the
engine be it dirt or water you have to clean it out really good and reoil
before the water has time to dry.. At the end of your flying day, MT the
fuel, start your engine to get the last bit of fuel out and use afterrun in
all the openings, Carb, exhaust then turn the prop over about 3-4 times
by hand..

Carefull here, I have had "crunchy" bearings from congealed castor oil. Run some fuel though it and it goes away. Not that rust can't cause this, just not the only reason. Also the bearings can get a light film of rust that you can't feel, the rust wears off when you run it, eventually the bearings will whine from the wearing off of rust which causes the balls to be out of round.

Another thought, I have had ringed engines that seem to lose a bit of compression before completly breaking in. Not sure why, maybe the ring rotates and needs reseating. Seems to happen if I only do a short break in on the stand. Seems to be running great and has good compression. Then I put it on a plane, it runs great for a while and then either dead sticks or is hard to start. The compression seems to be way off. When this happens the compression comes back after a few tanks of fuel, then the problem never returns.

I agree that congealed oil can sometimes seem like rust, and give a jerky feel when rotating the engine. It's pretty hard to tell the difference with out opening the engine.

Another side effect of running an engine that has a little rust inside is that the rust acts as a lapping agent and really wears down the piston and liner fit, causing a loss of power. This is espeically true in ABC engines. Ringed engines are more tolarant of that sort of thing.

i ran an abc engine after letting it sit for a while without after run oil.
i spray wd-40 to break up the gunk, but got too impatient.
the engine ran fine for a while then started to overheat or dead sticks.
particles ruin the sleeving and piston.
a ring engine might do better, never the less the enternal of an engine
should be as clean as possiable.
i didn't soak the engine long enough to get the gunk build up in the bearings out.

you can soak the engine pretty much still intack.
just remove the back plate, head, carb.
do it a couple if times if you have too, be patient..it'll save you money and headaches.
you don't want to soak o'rings or seals or rubber parts

there's also a tiny hole on the bottom of the rod to allow lubrication
of the thrust bearing in the rod or (brass bushing). makesure thats clean also

flacon 5

if you remove the sleeving, it'll allow room for the rod to slide off the shaft.
the cranshaft then should slide out from the bearing.

i don't know if the bearing is bad.. you might what to reconsider
or look into the cost of the bearnings.
is the engine leaking from the front?
is the bearing actually damage?

use a wooden dowl to hammer out the bearing..the bearing gets destroy in the process.
but if the bearing was bad that wouln't matter

not sure what you are determinding to be a bad bearing ?

on nitor engines sometimes the engine will not feel like it
rotating smoothly if the crank shaft is not pulled or pressed all
the way forward. generally on TDC or right before or after compression
stroke. if you mount the prop..it'll rotate smooth again.

I've done more engine tear downs than I care to think about (flying combat, filling engines full of dirt comes with the territory).

I really think you should find someone locally to look at your engine. It's just too hard to guess at over the web.

Hey Kirk.... I can see ribbons shared's maybe getting in the engine,
But how's dirt get in there:-)

when you crank the engine after you barried it 6" in the ground

It's called a lawn dart. The worst are when the other guy's prop cuts through your wing dowls or rubber bands AND he gets your battery pack leads at the same time. You're all ready at full throttle, and you sure aren't going to be slowing down any time before impact. If the ground is soft, it's amazing how far the dirt gets in the engine.

Some wreckage:


A bad sign:

Mmmm I see... Now I think I know why I see smiles on some of
the members faces, When they keep telling me to get in on this
wing deal so we all can combat....

Hey Kirk, Seems to be hard enough just staying out of them trees,
much less dodging those other planes:-) But I know it sure must
be fun!! I use to combat with C/L with the family back in them days
the most I flew with was 8.. The middle of the circle sure looked like
a circus...
You have fun... And darn it keep the dirt out:-)

The trees in the first picture are in Hamilton, Ohio. They have a couple of contests a year there. It's a fun field to fly at. Those trees are just the perfect depth. You can usually comfortably fly inside them, but they ARE close enough that you can also fly behind them. And chases around the trees for the last streamer are a real hoot.

And yes, sometimes guys hang 'em in the trees. At one point at the last contest, there were 3 planes hanging up there. They all came down, and I think 2 of them flew again that day. (and, fwiw, the red plane on the left is me. It's not in the tree, but I'm running from the guy on the right, and getting as close to the trees as I can).

The second picture is my home field in Maryland, and that IS my wing fluttering down after someone cleaned it off my fuse. The power lines in the picture are a lot farther away than it looks, well out of the way.

Looks like a lot of fun... Top pic... Not so much fun..Bottom pic..:-)
Here we can run but we can't hid so to speak.. Well I guess we could
go into the washout.. Hey that looks like a lot of fun.. Nice pics.. Was
anything left of your fuse?? Well I better get off of falcon 5's thread..
Thanks for the headsup and pics!!