mrbonk

Greetings,
Some of you may remember a post I made a little while ago about the innards of my OS.46FXH engine being rusty. At the time, I had assumed that it went rusty because it was left hanging on the wall without being run for around 3 months, plus I didn't put any after-run oil in it. Well, I'm starting to wonder now. At the time, I replaced the bearings and cleaned up the rear of the crank. No rust left in the engine. I replaced the piston and liner with a custom set I got from an engine builder here in Australia and I have run the engine every weekend since then. On Sunday just gone, I took it out for another run and it just didn't run right. So, I got around to stripping it back down today and to my amazement, there's the rust again! The rear bearing is rusty (and crunchy when you turn it), as is the rear of the crank again How can this be so in such a short time? I fail to see what more I can do to stop this thing from going rusty. It's been run on 10% nitro, 20% oil (Klotz) fuel and there was *plenty* of oil left inside the engine when I pulled it down today, even though I have been making sure I run the engine totally dry of fuel after each session. Any opinions out there for what's going on here? I'm starting to consider pulling the backplate off after every session and filling the engine with WD40!

Hobbsy

My Feedback: (102)

Bonk, I believe I've seen it written in these pages that WD-40 actually causes rust, I personally use Corrosion-X that I get from Sheldon's in California. It is designed to prevent corrosion in sea salt conditions. If you remove the back plate after a year the C-x will look exactly like it did the day you sprayed it in there and the bearings will be shiny and clean. It does not ruin glow plugs. It is also a superior lubricant. I know this isn't helping your current situation but would prevent any future rust. YS performance sells something called Ultra Oil that looks pretty good too.

mrbonk

They don't mention it on their web site, so I've sent them an email to ask if there's an equivalent product I might be able to get over here in the land of Aus. I'll also have a look around the place to see if I can get Corrosion-X from somewhere over here. That's the problem with living here.....products that are widely used in the US are sometimes not even imported into this country

w8ye

My Feedback: (16)

Mr Bonk

Meanwhile just get some auto transmission fluid and squirt it into the glowplug hole. Get the kind used in the Holden or GM of USA type cars. In this country they call it Dexron III or Mercon. The glow plug hole may be easier to get to than the backplate? Get the oil in the engine and work it around in there some. Next time you get ready to use it just fuel it up and go. Make sure you don't have it hydrostatically locked though.

Good luck,

Jim

splatt

Did I read previously that you mixed your own fuel?
I myself did a little experiment with my OS 32SX. I used morgan 15% fuel that 50/50 caster/ syn mix and when I was done flying I ran it dry and stored it in my basement for the winter without any after run oil and it was clean as of last week. Maybe the additives they put in helped?
Did you use those plasma liners? How did it perform?

miderror

have used Corrosion-X for years and have no problems. In fact
I started using it when it was call ACF 50 or something.
I'm in FL everything rust if not protected.

miderror

go to the local airport, it is for full scale planes. I get it at the
local FBO.

downunder-RCU

Well that's what happens when you live in muggy old Queensland
If you're using all synthetic that might be the problem. The synthetics (apart from the turbine oils) aren't very good wetting agents..they tend to just slide off steel parts. I'd add a bit of castor to the fuel, at least it's a built in after run oil

dyerstown

How much castor is needed to prevent rust (and maybe help lubrication?) I have been using stock Red Max 10% and Cool Power 10%.

Thanks!

Sport_Pilot

I have seen your site and I still think that your rust is not rust. We can argue what constitutes crunchy, but until you clean the crud and or rust off the bearings you will not know if it is rust or not. If after cleaning the bearings are still rough, only then will you know that it was rust.

w.pasman

Hi,

I had the same problem with an OS32. See my web page www.cg.its.tudelft.nl/~wouter. Haven't had the problem since this this first time.
I am using a little afterrun oil (20 drops or so, brand 'tornado'). Also I always run the engine dry after flying, by disconnecting the fuel line to the engine while it runs, and emptying the fuel tank and fuel lines before reconnecting it (fuel may flow even if the engine is standing still!). Remember that methanol attracts water, and that nitro with water gives nitrous acid which is bad for the bearings (surprisingly, aluminium seems more corrosive resistant in this respect).
Alternatively, your engine may be running hot, causing damage to your bearings.

w.pasman

Something else, On your webpage you say you drilled a hole to reach the carb to pour afterrun oil in there.
I just use the fuel line to pour afterrun oil in. The manual says that's not a good idea, as this could detoriate the rubber rings, but hey nitrous acid is good for these rings!

Steve Collins

My Feedback: (8)

I thought I read in one of your posts above (reading between the lines) that you weren't real good at applying afterrun oil after every flying session. These engines can rust in an incredibly short amount of time. I have even heard that this can happen as quickly as overnight. It is sometimes a pain to remember to do so but it is very important to use the after-run oil after every single time at the flying field.

Sport_Pilot

"but hey nitrous acid is good for these rings"

You don't get nitrous acid from wet unburned nitro. It is a product of the exhaust and quickly reacts with unburned fuel and other products. It reacts quickly with aluminum. In fact the old sanblasted style of mags are a result of the fact that the old slingshot AA dragsters would "frost" the polished aluminum on the mags. This was the result of the high acid content. The drivers wore gas masks because of the toxicity of nitrous acid. If the bearings are rusting and the aluminum is not pitting or covered with a whiteish powder then acid is not the problem. In fact our bearings are corrosion resistant but not stainless. Good hard bearings are more corrosion resistant than cheap ones. IMO its carbonized oil. If the engine is running hot as many helecoptors do then the oil may cook on the bearings after shut down. If this is the case most afterun oils will just cook more quickly than afterun oil, and castor would be worse than synthitic. Just a theory you don't know till you clean the bearings by soaking in a crock pot of antifreeze or carb cleaner.

fiery

My Feedback: (2)

Bonk,

Go to your local super-cheap or autobarn and get a can of Inox.
The jet boys swear by it as an after-run.

Me, I tend to use good old ATF which seems to work OK. I add it immediately after the last run of the day through the carb (2 stroke) or breather nipple (4 stroke). Turn the engine over ten times to really work it through.

regards


fiery

Mighty Mouse-RCU

My Feedback: (145)

Its hard for me to believe it is rust after only one week guys. Could this be something else?

mrbonk

Fiery,
Do you have to flush the engine before your first flight next time? When I used the after-run, I had to pull the plug out and flush the engine before the first flight of the next session. The starter just wouldn't turn the engine over if I didn't.

Ladyflyer

My Feedback: (2)

Quote:
"If this is the case most afterun oils will just cook more quickly than afterun oil, "


Huh?

Dave Bowles

My Feedback: (7)

I had a Saito 30 that was on a float Plane rust overnight, I dunked it into the water once and ran it at least 5 times after that for a total of about 45 min. I use Caster blend fuel but I should have broke it down and cleaned it , so if you are told your 4 stroke will be O.K. after dunking it in the water at a float fly , Don't Believe it, Break it down that night and get all the water out of it. Using the Caster blend I don't have any rust problems and very seldom use After run oil when using an engine regularly.

Sport_Pilot

That should have been that after run oil will cook more quickly than synthetic oil. Most afterun oil will burn at a lower temp than both castor and synthetic oil. Synthetic being the best.

downunder-RCU

I can't imagine how a ball race could possibly get hot enough to carbonise any type of oil. Even an engine that seized from a lean run wouldn't heat soak the bearings anywhere near the temperatures needed for that.
Now here's a pure guess, stab in the dark, wild thought. It appears you're using this engine in a helicopter? In that case there'd be very little (if any) thrust load placed on the bearing and it just might be that the crankshaft is rattling back and forth (much like a plain bearing prop engine does at idle) and this could cause brinelling of the tracks giving the roughness. The crank may not have any fore/aft play when cold but as the crankcase warms up the differential expansion may remove any preload on the bearing.

fiery

My Feedback: (2)

Hi Bonk

I don't seem to have problems with hydraulic lock when starting engines. With the 4 strokes, I carefully turn them over to ensure their is no lock. It is unlikely as the excess after run is expelled though the breather vent and a little sometimes comes out the front bearing. I don't routinely add after run to the the top of a 4 stroke through the pug hole as corrosion here is not such a problem. I only do it if I am "laying up" the engine for an extended period of time.

With 2 strokes, there is a mutch greater chance of hydraulicing. I like to check the exhaust is facing down before I carefully turn them over prior to starting. Any excess after-run oil just dribbles our the exhaust port. What's left doesn't seem to burn or foul plugs. I understand that ATF's flashpoint is higher than the temperature our engines work at.

These procedures seem to work for me. Hope this answers your query.

regards


fiery

mrbonk

I think I've solved the problem of my rusted rear bearing. I just purchased a stainless steel one Now, if *this* one goes rusty, I'll be *very* upset I also spoke to a friend who knows a guy who knows this dude (you get the picture....) who runs an alcohol drag bike. He reckons my problem is that I'm storing the heli in my garage, which contains my tumble drier. Too much temp variation and condensation from the tumble drier and voila.....moisture in the engine. So, I'm also going to rig up something to get the exhaust air outside directly (via a ceiling vent or something). Maybe I'll get this engine to stay clean yet!!

Dave Bowles

My Feedback: (7)

I spoke with the Boca Bearings Rep at The Toledo Show about Stainless Bearings, He informed me they are not rust proof because they are not 100% stainless steel, They still have Carbon and can rust. They do have less carbon than standard Bearings.

Jazzy

Carbon--rust?
News to me.
Metal alloys containing ferrite will definately rust providing the concentration is high enough.