tz250w

As the title says. I have two pumpers, YS FZ110 and an O.S. FS70 Ultimate. I have a choice of ATF or air compressor oil on hand but my hobby shop guy tells me not to use anything that will harm the diaphrams or other silicone parts... []

Ram Jet

I seriously doubt that ATF or compressor oil would harm your rubber parts but I can't say with certainty. An automatic transmission is loaded with O rings and rubber gaskets but of what composition? I would with certainty use a product called G96 gun lube and moisture displacer. You could consider Mobil One Synthetic ATF and E-mail Mobil with your question before trying it. I don't think pure castor would offer the moisture protection that a modern lubricant would and would probably gum-up over time.

Let us know what you find out. As of now I intend to use Mobil One synthetic ATF but my engines aren't constructed the same as yours.

Bill

rcdude7

My Feedback: (264)

Don't use any petrolium oils in your YS, it will attack the silicone parts in the fuel system. I have been using the ultra oil that is sold by YS performance, it is cheaper than replacing parts in the engine.

Oils like mobil one are not without petrolium components, so I doubt you are safe there either.

Flyer95

My Feedback: (1)

The best thing is to not use any kind of after run oil as it will cause you more trouble the next time you start up the engine. If you wanna use some kind of oil then look for a syntetic or castor/syntetic oil, the same oil that is in your fuel and that will mix with methanol.

The best way to protect your engines against rust is to do nothing but to store them with the propeller pointing vertical.

ATF and petroleum based oils should not be used in pumped engines as it may harm the silicone parts and they will not save the engine from rust if you store them the wrong way "propeller pointing downward".

JNorton

My Feedback: (2)

Mobile One full synthetic 5W30 wil not harm the diaphrams. I only have one pumped OS 120 engine - for everything else I use ATF but not on the OS. Rusting highly depends upon the climate where you store your planes. My old basement was very humid and I had real problems with rust even though I made sure to run out all the fuel after each flying session. So I started using ATF wich helped a lot. In my new house the basement is not humid so I suspect I will not have problems.

John

freakingfast

My Feedback: (3)

YS pumped two strokes heli and plane as well as their four stroke engine use silicone parts. I do not know it OS uses silicone in theirs.
Petroleum and some synthetics will attack the silicone parts, so why take a chance if you are not certain.
Ultra Oil made by Performance Specialties is proven oil for both YS and OS engines.
I have used ATF for years in non-pumped engines in the past.

For a while now I have not been using any after-run oil and my engine bearings are better than ever!
When I'm done flying, I empty the tank, refill it 1/4 full with FAI fuel (80/20 or 0%- no nitro fuel), start & warm it a moment and run it at WOT for 30 seconds, pinch off the fuel line to stop the engine and empty the tank or empty the tank, than run the engine dry. Note! Pinch off the fuel line or run dry a four stroke at low RPM only or you could throw a prop if it lean back fires!
When running FAI fuel the engine will be rich, but there is no need to adjust or you may loose a good needle setting for the nitro fuel (unless it refuses run over 50% of speed).
What you end up with is a nice coating of caster oil when the heat helps cook away the methanol.

I’m convinced that I can’t just run it out of nitro fuel and use after run oil to get rid of the nitro. I found that if I don't “Hot flush� it with FAI fuel, a few days later there is a very subtle gritty feel to the bearings. These are little rust spots on the balls and races from acids formed by leftover nitro residues. In time it can destroy the bearings.

Nitro boat racers have been doing this for years, I just wish I found out about it sooner.
This has been one of my greatest finds in this hobby.

Pictured is a OS 70 heli thats run on 30% wild cat heli fuel than flushed with FAI at the end of day. It has over 70 hard runs on it. Note the total lack of rust! And the bearing are smooth as silk.

David Bathe

Now that freakingfast, is a very interesting concept!

flyby50

Hello, please let me know the difference between the FAI fuel and others, the engine looks great and i would like to try this, thanks....

flyby50

After reading a little it seems that FAI has no nitro, but i thought the other things in the fuel made it rust an engine, maybe its the castor oil helping with the rust, i really don't know .....[sm=71_71.gif]

Flyer95

My Feedback: (1)

A few % castor oil in the fuel protects engine internal parts against corrosion. Methanol is hydroscopic and absorbs water and combustion byproducts from fuel with nitro is been said to be corrosive and cause rust. But you either have a rusting problem or have not. Me and a few of my clubmates use 10-20% nitro and about 20% castor/syntetic oil package in our fuels and we never do anything to our engines other than flying with them. Its been so for the last 8-10 years and we fly all year around.

w8ye

My Feedback: (16)

Nitro makes nitric acid?

flyby50

I did an edit on my thread, what i meant was maybe the castor helps to protect from rust, i know one thing, I HATE RUST !!! are you running the engines dry or not, thanks....

w8ye

My Feedback: (16)

One thing that has never worked for me is to run them lean WOT until they run out of fuel. Then let them set with no ATF. You are sure to have rust.

flyby50

Thanks neighbor, i tried alot of things and still have rust, my basement is damp and i'm sure that does not help, i think i'll try the zero nitro trick- that guys engine looks great oh well, keep warm brother, thanks - flyby50...

w8ye

My Feedback: (16)

You and I live at each end of the coldest part of the state

It was certainly slick and miserable out side today.

Needless to say I didn't run any engines

freakingfast

My Feedback: (3)

After 30 seconds of WOT, than reduce throttle and cut the fuel supply is the right way, it’s what I've been doing, I just didn't spell it out. And the four strokes should be near idle when the fuel is removed.
Sudden fuel removal rather than a lean run is preferred. Even easier on the engine/glow plug is cutting off the fuel at lower RPM.

Good catch.

Prior to this it seemed that I was getting real good at swapping out red rusty pitted bearings, now it’s been a while. I don’t miss it. The engine pictured in the earlier post had to be inspected for dirt after the plane went gopher hunting. Luckily I had time to close the throttle and no harm done.

Roguedog

Hey all, here's my 2 cents worth.

Never use automatic transmission fluid in your engines. AT fluid has a high concentration of detergents in the fluid that is not compatible with silicone. I used to rebuild transmissions and if you ever used silicone sealent on a pan gasket you find that within a month the silicone is goo, I mean slimy goo. You find this out cause it leaks like someone punched a hole in the pan.

I concur with Flyer95 but would like to add - from what I have read it's not just the combustion by-products and nitro it's the combustion by-products from the nitro and synethic oil that is culpret. The syn oils are extremely corrosive after combustion.

Aside fron the syn oil and nitro I believe only two causes could contribute to the rusting problem. First as Flyer95 said methonal is hydroscopic, which means that if any methanol is leftover in the engine after running it's going to act like a magnet to any moisture it can attract or draw into the engine.

Two after running the engine, even if you pinch the fuel line and let the engine run dry, as the engine cools condensation will want to build up inside the engine. If it's real humid it's worse. Any one ever notice that on navy ships and carriers they cover the guns and cowls and exhausts of airplanes to keep out the moisture.

I just wrote in another thread that unless it was NIB ever engine I have gotten of ebay has had rusted or gummed up and rusted bearings.

IMHO the only way to keep the engines relatively dry is run the engine dry and immediatly plug the carb and exhaust while the engine is still hot. Shouldn't be much moisture in the engine while it's hot. The only other way would be to evacuate the engines crankcase with a vacuum to remove the moisture similar to what they do on a/c units right before they recharge with freon, then plug the carb and exhaust.

If you find rust after plugging the engine then the only culpret left would have to be the syn oil and nitro combustion by-products

Bryan

Cyberwolf

My Feedback: (4)

Pictured is a OS 70 heli thats run on 30% wild cat heli fuel than flushed with FAI at the end of day. It has over 70 hard runs on it. Note the total lack of rust! And the bearing are smooth as silk.

Just a quick question if this engine was in such great shape why was it tore down????????

blw

My Feedback: (3)

Nit picking here, but our fuel is hygroscopic.

Synthetics are doing a poor job in preventing rust right now. This is where some castor in the fuel works well.

freakingfast

My Feedback: (3)

See post 16

tz250w

Thank you all for the replies and continued debate. I think a lot has to do with the humidity level where you live. For us here in Nipponland it's high, year round so rust is always a problem (not to mention most of us live within sight of the ocean...).

I've found with my heli (O.S. .50 Hyper) (recently traded for more "plank" stuff...) that running it dry devloped a bit of "goo", probably spent oil that gelled while the engine was still hot. If I shut it down manually (thottle cut), then drained all fuel via the fuel pump (last by pinching the tank line to draw a vacuum on the carb) it was still "soft" and smooth the next weekend. A few guys at my club that were afraid to open their engines gave me them for an "overhaul". I noticed that most that ran them dry had the "goo" coating, even inside the sleave (between the sleave and cylinder) where those that didn't run them dry, like me, still had a smooth coating of oil. The rust (to me) seems to be more of a humidity problem which is kinda why I posted this thread in the first place.

I'm an old motorcycle racer, so breaking down a small glow engine is fun (my hands don't get dirty and I don't need to break out my torque wrenches and "special tools"). However, I'm not into chemistry or the do's and don'ts of glow fuel. I'm just looking for a safe way to keep my silicone parted engines safe from the dreaded RUST between flights. With the two stokes in my helis, it was a given... fly each weekend.... Now that I've decided (confirmed, though the helis were a fun challenge and steep learning curve) I really like things with wings better I have a few that don't get flown so often.