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-   -   OS 65AX ABL "rust" issue (http://www.rcuniverse.com/forum/glow-engines-114/11388373-os-65ax-abl-%22rust%22-issue.html)

donalddrew 01-28-2013 09:26 PM

OS 65AX ABL "rust" issue
Recently had an OS 65AX ABL seize during flight of my Dirty Birdy. Engine had maybe 25 flights on it. Sent it in for warranty work to Hobby Services. Their findings: rust from rear bearing went through engine destroying front and rear bearing, cyllinder line and piston. I run Wildcat fuel 10% nitro 18 % oil (synthetic/castor mix). At the end of each day I run the engine dry, and use after run oil (Hobbico or Zap). As well, the longest the engine has sat between flights is about a week. I live in San Diego away from the coast (dry climate) When I told the rep from Hobby Services this he said I need to use at least ateaspoon of after run oil after each session! Sounds crazy to me. Any ideas out there? Are these guys just blowing smoke up my exhaust pipe ? Any similar issues with rust in OS engines? Could it have just been a faulty bearing? Am I doing somthing wrong??? Now I'm recently back into the hobby after a 30 + year hiatus. Back then I neverused after run oil and never had an engine have any rust issues. Am worried that if this happens again, they won't cover the repair.

jeffie8696 01-28-2013 11:06 PM

That is serious smoke. http://www.rcuniverse.com/forum/js/f.../sad_smile.gif

Sport_Pilot 01-29-2013 05:00 AM

Pays to look at the bearings before sending it in. I have long suspected of OS hobby services of lying as almost all engines are claimed to have rust. However, I have also long suspected of petroleum after run oil to be the actual cause ofrust, especially if the engine isn't run dry and allowed for the methanol to evaporate before adding the oil.

AMB 01-29-2013 06:36 AM

ATF any supermarket or auto parts store makes a good after run treatment a quart will last a long time. I run mainly diesel ether kerosene and castor never any issues wit this no alcohol which attracts moisture combined with the nitro forms acid martin

Post note on my glows I put a little model diesel fuel hook up plug and run it thru for a few seconds NEVER a bearing or rust issue 2 or 4 strk

regardless of what you use remove the glow plug pour some in, flood the engine flip prop then dump out

jaka 01-29-2013 06:46 AM

1 Attachment(s)
Come on guys!
Steel rust! nothing strange about that eah?
If you want an engine to function well you have to maintain it! That means you have periodicly (once a year or so) change the bearings!
Ball bearings wear out, both from hammering of the piston and also from rust, and if you do not fill the engine completely, or there about, after each flying session with ATF oil or a modern syntetic oils like Fuchs Aerosynt 2 or 3 or the French Motul "Micro" all synthetic oil...your engine bearings are going rust! Simple as that.
Castor oil does not help in prohibiting rust either, so wheter you are using syntetic oil or castor oil ...fill the engine with a rust inhibiting oil like the ones I mentioned above or use a spray oil like WD -40 , 5-56...but do remove the engine back plate from time to time and check the rear bearing. It's the rear bearing that is most likely to rust and takes all the load and hammering!

AMB 01-29-2013 07:13 AM

JAKA has a good point but if you remove the plug whatever you use will get a lot in the lower end with piston at bottom shake rotate dumo no need to pull backplate
Just use enough to do the job, pouring some down the intake will not do it martin

earlwb 01-29-2013 07:31 AM

But the OP's original problem was the bearings went bad after maybe25 flights using a new engine. If you flew the engine for five flights a day, that is 5 days of flying. So at about 10 minutes a flight that is about 250 minutes or betwen four to five hours of use. Since the Op had justy gotten back into RC flying I would assume he is flying a lot at first too. Not one day every couple of months or so, I would assume that with frequent flying, it wouldn't matter if the OP used all synthetic oil glow fuel or all castor oil glow fuel or a blend of both oils. Neither would the amount of nitromethane in the fuel matter for such a short time period.

I think the bearing was out of spec and simply failed prematurely. The rear bearing has to take most of the load and stress. I don't see rust setting in that quick with a engine being used frequently either. That tends to happen mostly when engines sit idle for a longer period of time.

Sport_Pilot 01-29-2013 08:21 AM


once a year or so
Balderdash. I have never changed out a bearing because it had to be, (though TT did for me under warranty). Though Ihave changed them out because I was overhauling the engine and the bearings were a bit worn.

If you use castor oil in your fuel and run it dry they will last indefinately. The nitro will not harm bearings and is only very slightly acidic, as is methanol. The nitric acid fromed when burning goes out the exhaust and is not around long enough to cause any damage. My high nitro engines have about the same issues, namely none.

The only complaints seem to be from people using after run oil.

earlwb 01-29-2013 08:29 AM

I haven't used after run oil in any of my engines. I haven't used ARO since I first got into the hobby.

blw 01-29-2013 08:45 AM

Bearings can last for years and years without changing them out. WD-40 is a water displacer and not for rust prevention. These things need to be mentioned for those who are just learning about engine care.

MJD 01-29-2013 09:22 AM

If I had to change bearings every year of normal service, I'd take up a different hobby. That's ridiculous. I appreciate and understand all the things we should do to keep our engines healthy, and I frequently do these things but in practical terms I am a bugger for just running the engine dry at WOT and pulling the fuel line then heading home. Then returning 1 or 2 or ? weeks later to fly some more. I don't seem to eat bearings as a result. I always use syn/cas blend fuel same as the OP.

I just changed bearings in my first engine in a long time out of necessity - and I haven't even run it myself, it is a lightly used Moki 2.10 that arrived with the rear bearing rusted to crap.

Come on, 25 flights and the bearing is shot? If it's not a mfg/component defect then the OP must be using salt water as after run oil.

Sport_Pilot 01-29-2013 09:53 AM

Funny but Jaka's rusted bearings look cleaner than bearings I have left in my engines for decades.  Looks like oil stain to me.

airraptor 01-29-2013 10:13 AM

All you guys are missing the big problem....OS is buying substandard bearings. The bearings they were using in the past have changed. They might be buying the same bearings from the same people, but the bearing MFG has changed the bearings and we are no seeing more failures. If you really dig on the net you will see all bearings from OS,Saito and many others are failing more than they have had in the past. So the bearings have changed or the fuel has.

by the way I never run my engines dry or run any kind of after run. I think the guys that use the after run are just buying into the HYPE thet the MFGs put out. LOL its like the old saying that you have to change your oil every 3,000 miles.... lol this came from the oil companys suggestion to the Car MFGs.

If you go and look at the part numbers from the older AX I engines you will see they changed the part number when switched to the AX II. also the 55 AX uses the same bearing.

Tower isnt doing very good with the repair work. Why have a 3 year warranity when they dont honor it!!

AMB 01-29-2013 10:59 AM

you guys may be right on bearing qualilty Saito, OS, and the others get them as an OEM ( offer extended to manufactures ) the best bid gets the contract

no way from Europe or US maybe China or India martin

MJD 01-29-2013 12:07 PM

Original Equipment Manufacturer.

The use of sub-par bearings neatly explains all the observations and comments, which in a nutshell are a hit or miss service life seemingly independent of the level of care by the user.

1QwkSport2.5r 01-29-2013 01:34 PM

There was no mention of blowing glow plugs.. Isn't that a common issue when the bearings start shedding material?

It's funny you don't hear about stuff like his happening with TT or Evolution.

pe reivers 01-29-2013 01:44 PM

All posters had some merit her. However, all the good materials for our engines have specific corrosion requirements too!
The crankshaft is a carbon steel that needs to be protected from the very corrosive by-products of Methanol combustion. Nitro-methane ads to the problem in no small dimension.

Having said that, the end user is to blame, mainly because he did not get the proper instructions to keep his engine free of corrosion after he shut it down at the field.
EVERYbody knows about the use of "after run"treatment", unless you are a novice at running glow engines. (here lies the problem)
Problem definition:
1) methanol is hygroscopic, it attracts water. After running, there will be traces left.
2) nitromethane combustion residue is acid in nature! with water the acid becomes active and attacks metals.
3) results of 1) and 2) is corrosion inside your engine!!! No if about it.

How to prevent it??
1) Get rid of all methanol traces after running your engine
2) get rid of all Nitromethane combustion products after running.

That is what after run oil is for. You however do need to run your engine a while to get rid of all the stuff that accumulated there.
Make a mix of cleaning naphtha and Transmission oil (I used ATF claning naphtha 50/50)
Run the engine several blasts on this mixture.. it gets rid of all the corrosive by-products.
Due to the high oil content, the engine is well lubricated for storage.
Wrap in a plastic bag, and forget about it till next use!

I use this mix to run an engine that feels tight after years of storage to free it up again. (I use gas engines lately)

Where did them plastic bags go? Are they needed when I store engines in a tight box???

Sport_Pilot 01-29-2013 01:58 PM


by the way I never run my engines dry or run any kind of after run. I think the guys that use the after run are just buying into the HYPE thet the MFGs put out. LOL its like the old saying that you have to change your oil every 3,000 miles.... lol this came from the oil companys suggestion to the Car MFGs.
The car manufactures do not recommend 3,000 miles the manuals say either 6,000 or 7,000 miles. The dealers recommend 3,000 so that you have to pay them for more oil changes.

Sport_Pilot 01-29-2013 02:01 PM


The crankshaft is a carbon steel that needs to be protected from the very corrosive by-products of Methanol combustion. Nitro-methane ads to the problem in no small dimension.
We are talking about a two stroke, there are no combustion products in contact with the crankshaft of a two stroke. Besides that only a little bit of methanol will burn off the excess nitric acid. The only place I have seen corrosion from nitro is off the zoomies of a dragster, and then all it did was to frost the mag wheels and other aluminum parts down stream of the dragster.Nitric acid is very reactive and used as an oxidiser for large missles. It will mix with the unburned metanol componets and not leave any nitric acid. I have never seen any more corrosion in a high nitro engine than any other. In fact I would say better, probably becase there is less methanol to asorb water.


That is what after run oil is for. You however do need to run your engine a while to get rid of all the stuff that accumulated there.
Petrol based after run oil only hurts, it does not help. Even though you run the fuel dry there is still some methenol in the crankcase. The after run oil does not mix with methanol nor any water trapped in the methanol. Instead it traps the fuel and water against the surface causeing pitting. If you want to use afterrun oil I would recommend a 50 50 mix of castor any synthetic oil.

fizzwater2 01-29-2013 02:04 PM



ORIGINAL: 1QwkSport2.5r
It's funny you don't hear about stuff like his happening with TT or Evolution.
part of that may be sheer volume. I'm guessing that OS has sold more engines, hence you hear more about them.

Not that they're any better or worse, they just sell more.

Tony Iannucelli 01-29-2013 02:31 PM

Wow, reading this string is really interesting. There are guys on here with over 12,000 posts. 12,000! That's a lot of time spent typing instead of flying, for whatever reason. Sorry to digress, but geez, what's a new guy to think? No offense intended by the way, really, none at all. If you have the time for all those posts and they are based on facts, not just opinions, I'm all in favor.

I've flown OS, YS, K&B, Enya, Fox, and a bunch of others for 40 years. I've lost some engines to bad bearings. My fault, I ran them too lean, left some fuel in there, did all the bad things. In the early days I used castor oil and later a blend of castor and synthetic. I used to run Duke's 10% stuff and Missile Mist, have tried Byron, and several others. I've settled on Cool Power 20/20 and PowerMaster 20/20, all synthetic. Since I went to those fuels I NEVER had issues caused by rust in planes or helicopters. I did destroy some bearings when our field was dusty, and under reconstruction. Dust "hones" out engines and gaffes up bearings. But modern synthetic is the way to go on oil, and 3 in 1 "air tool" oil is the way to go on after run. (Walmart has it). I fly a lot and only use after run if it's easy to put in an engine. I put 20 drops in the carb and 20 in the plug hole especially if I know I'm not going to fly that particular plane again soon. I think it's most important to burn off the residue after a day's flying.

Castor oil used to be good stuff in engines, and still is, but only an ounce or two added to a gallon is necessary if your engines are adjusted properly. Modern synthetics are really miracle oils, and a good analogy is Mobil One in cars. The old timers even use Mobil One, but still insist on changing it every 3,000 miles in their cars, which is ridiculous unless you get the oil free. You can EASILY get 10,000 miles on Mobil One in a car engine with NO wear whatsoever. Most cars today have 5,000 and 7,500 mile intervals anyway. But back to castor. We run helicopters with 20% oil, 23% oil, and 20 and 30% nitro. We can't use after run, engine position doesn't allow it. We don't have bearing problems generally, and we don't use castor oil at all. How do we get away with? We don't run too lean, and we use quality fuel. Helicopters are high heat environments. Synthetic works great, we don't bake on crud on our mufflers and cylinder heads, and we don't glaze the bearings and pistons with castor. But some people have done the same thing for so long they won't try anything new. They are missing out. Try upping the oil content in your fuel with helicopter labeled fuel. A dollar or two extra a gallon is worth it.

Tower Hobbies and Hobby Services are great in my experience. They are fast, honor their warranty commitments, and are fair. OS states the warranty is good if you don't abuse the engine. They even cut slack on that.

Welcome back to the hobby. Check out the guys at the field that are having a good time, who's engines always seem to run well, and who are respected for being good guys and good fliers by their peers. Ask them what they do. And you have fun too. -Tony

airraptor 01-29-2013 02:37 PM



ORIGINAL: 1QwkSport2.5r

There was no mention of blowing glow plugs.. Isn't that a common issue when the bearings start shedding material?

It's funny you don't hear about stuff like his happening with TT or Evolution.

quicker is correct the plugs will start to blow as the bearings are letting go, but if getting to that point its to late. I think the reason for the evo engine not having an issue is like stated the volume and they break cranks before the bearings go.


Most of the guys at my field are retired and they fly 6-7 days a week all year round. The OS bearings 46-120 AX will last anywhere from one month to 6 months. It varys all the time. all of these guys run their engines out at the end of the day. The ones that have been lasting the longest for OS engines are the 95V four stroke. I really think the bearings have changed in the last 5-8 years. I have been flying since mid 70s and till around 5 years ago never had issues with bearings.

Now thinking outside the box maybe it has been the fuel that has changed. we all need to remember the World economy has changed and everything is getting more expensive yet the people making items for the world still want to make a profit. So with that they have to find ways to save money. Some of these may choose to make products that are not how they used to be. Like I said I never use after run oil when an engine is mounted on a plane. If I have an expensive or rare engine I will pull the back plate clean as best I can and the soak the whole engine in trans fluid Dextron III.

KLXMASTER14 01-29-2013 03:24 PM

Change out the bad bearings with 440C Stainless bearings from Boca Bearings or R/C Bearings, and your "rusty" bearing problems will go away.

Like the OP, the bearings in contemporary OS engines (.46, .55, .65, .120AX) have all had short lived bearings.

Good luck,

hairy46 01-29-2013 04:47 PM

Rust has not been a problem for me but I do oil after each run with air tool oil with rust inhibitor and reoil a couple times a year if not using. But I do smell smoke in your case!

ovationdave 01-29-2013 05:27 PM

I have engines I have ran for 15+ years. Never used after run oil, never did much at the end of a season let alone the end of a flying session. Never had an issue. So my conclusion is that if this is a problem that is occuring now, its because of cheap materials in the new bearings. I have never had an issue with my engines. Maybe I am lucky, maybe I'm a goofball, but I know one thing, if I had to replace bearings every year, I would be spending most of my airplane-building time rebuilding engines. This issue sounds unreasonable to me, and using a teaspoon of ARO after each day? Sorry, if that what it takes to keep your engines running after a week of down-time, I will switch manufacturers.


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