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HelicopterEngines Plugs Mufflers Fuel › Engine bearing rusting
09-02-2003 11:44 AM  14 years agoPost 1
Secret Squirrel

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New Zealander living in Melbourne, Australia

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Hi everyone,
I pulled the engines (OS 91's) out of my Vigors tonight to check up on them and found that the bearings in both had 'rusted'. The bearings themselves felt OK, but I'm swapping them out nonetheless.

Both machines have MPII's on them and I've heard a lot about this muffler allowing fuel to return back into the engine and 'pool'.

What's the deal here? Any measures I can take to prevent this in the future? Don't want to hear "Use castor" either!

Si

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Simon Lockington

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09-02-2003 02:07 PM  14 years agoPost 2
Steve Campbell

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Baton Rouge, LA

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<>

So, either go through the hassle of getting after-run oil in the engine, and risk hydro-locking the engine and bending your con rod, or put up with rusty bearings.

Personally, I have found that the one ounce of castor per gallon to be a lot less headache; but that's me.

Steve

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09-02-2003 02:24 PM  14 years agoPost 3
MJA

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UK

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Simon,

One of my older 91 OS's had a rusty back bearing before it ever got into the heli.All i'd done was run it on a prop and std aero exhaust (which i took off when i'd finished )then left it in the blue box for about 1day before fitting it.The bearing was rough as well as rusty on the outer race.I can't believe it had done that just over 1 day and thought it must have had it starting to begin with.The second motor was my own fault,i left the motor+heli stored in an unheated building outside during 2 weeks of wet weather wit loads of neat fuel still in the crankcase
I tried to turn the engine over and it appeared to have seized.When i took the muffler off a load of rusty coloured oil and a layer of neat fuel pissed out,the main bearing was knackered. The fuel had some castor in (2-4% per gallon) but didn't stop the corrosion setting in.


From a prevention point of view,it's best to clamp off the exhaust pressure line and the carb feed after use (with fuel shutoff plastic clips).Also when you clamp off the fuel inlet,reconnect the glow and hit the engine with the starter until it won 't fire no more or show any signs of it.

The best sure way if you can get to the backplate easily is to either take the backplate off and oil it manually,should also let out any neat fuel left in the bottom at same time.Or you could fit a backplate pressure tapping (the same as for perry/kline use and use a syringe to get neat oil in.Only trouble is you'll probably have to drop the glow plug for the first start the next time out or it'll be nearly impossible to turn over/start ie hydraulic locked with too much neat oil in the crankcase.

Generally should be ok for longer periods with no after run attention, except the starting with the fuel shut off at end of the day,but only really if the heli is stored indoors and you fly at least once a week.A lot depends how much moisture is in the air as to how fast corrosion sets in,also the nitro content.Never had much trouble when i only ever used 5% or if it did it took a long time to develop.

As far as the MPII goes,it is definately a pain when mounted with the extender the way up where it tends to drain back into engine instead of into the can,though most of it is oil rather than neat fuel.Can't see a way around it except maybe

Put a pressure fitting on lowest point of the extender with an open pipe for storage
Make a heli rack to store it on the exhaust side facing down
Take the MPII off for storage(not a terribly good idea as they're a bastard to keep tight as it is:-)


Martin

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09-02-2003 10:09 PM  14 years agoPost 4
plantone

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Perth wa

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Hi Simon

I was told by Mike Sutton ( Cool Power Importer ) that it is the methanol that makes the bearings go rusty NOT the Nitro, Methanol absorbs the moisture in the air thats why it has acetone in it when you buy it neat. Maybe try at the end of eash day just turning the piston to TDC to close the exhaust port. I have just checked my YS 80 out of interest that is now 10 months old & there is only discolouration on the bearing like a scale effect no rust though.

Wayne

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09-02-2003 10:33 PM  14 years agoPost 5
Secret Squirrel

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New Zealander living in Melbourne, Australia

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Gidday Wayne,
Yeah I think 'rust' was probably too harsh of a term, but there was definately quite bad discolouration.

I agree about the methanol being the problem too. I haven't in the past 'run out' my machines at the end of the day, but I can feel that happening now actually. The TDC idea is a good one too.

Si

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Simon Lockington

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09-03-2003 12:13 AM  14 years agoPost 6
MJA

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UK

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Yes that is correct,it IS the methanol that attracts the moisture,the tech term i think is hygroscopic,however i have had more problems with bearing attack/corrosion with higher nitro in the fuel than say 5% or straight fuel ,which makes me think it's either a coincidence or nitro in the fuel or after it's been burned helps accelerate it somehow
If you read some of the model fuel makers blurb they say it can't happen , acid attack etc etc etc,it's purely down to the methanol
absorbing moisture.


Martin

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09-03-2003 01:36 AM  14 years agoPost 7
Doug

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Port Saint Luice Florida....

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I Know you don't want to hear it but Castor is the answer. But don't fly with it, just use it as an after run. Hears what I do when I'm done for the day I defuel then refuel just the header tank with my normal fuel (WC 15) which has a 1/2 oz per gal of castor. I then hover till it leans and quits. I then clamp of the fuel line and start it at idle to finish the fuel followed by WOT motoring with the starter for about 20 sec.since the engine is quite hot the volatile portion of the fuel is boiled away leaving only oil and the castor provides superior film retention. there is not enough castor going through to even notice on the inside or the muffler. I have been doing this for over a year and the bearing still look like new. additionally I then re fuel and defuel to purge the exhaust out of the tank to eliminate any clunk line deterioration and that's it. and it works

First member of Member of Bearings Anonymous

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09-03-2003 06:51 PM  14 years agoPost 8
Steve Campbell

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Baton Rouge, LA

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Doug,

Excellent idea regarding spreading the oil/fuel mix through a hot engine with the starter. The castor does tend to stick better than synthetic, anyway.

I might try that meself...

Steve

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09-04-2003 09:48 AM  14 years agoPost 9
helispanker

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Sweden

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I always run the engin dry the last flight of the day either by hovering until it stops or by removing the fuelline and run with the starter until all fuel is burned. Then I turn the engin backwards to the compression starts, then both piston and crankshaft shuts all opening off. Also carb at full closed. Then there is no way for moist from the air to reach the crankcase. From what I heard it will not harm the engin to run it dry.

Robert

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09-04-2003 08:57 PM  14 years agoPost 10
plantone

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Perth wa

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Hi Helispanker

I think that is probably the best way to do it, i dont like the way, Doug suggested by running the engine until it quits this to me is asking for long term damage to the engine by runnung the risk of overheating it or damaging the plug by overheating that then going dry, how long wil the plug take this of punishment before failing & sods law it will fail when you are flying it.

Wayne

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09-05-2003 02:45 PM  14 years agoPost 11
Agilefalcon

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Fort Worth, Texas

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After flying, I pull the glow plug and fuel inlet line. I then turn the motor over with my starter while shooting about a 1/2 oz of Marvel Mystery oil in through the carb's fuel inlet.

All my engines look brand new inside with no rust on the bearings or on the piston pin.

Before I started this regimen, I had one engine completely rust up in just over a day.

Chris.

Chris Berardi
Team BobbyJack's Hobbies

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09-06-2003 02:20 AM  14 years agoPost 12
JimmyY2KWS6

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Miami, Florida

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What's the deal here? Any measures I can take to prevent this in the future? Don't want to hear "Use castor" either
Yeah Use castor!! After the last flight of the day, I burn the remaining fuel in the engine, plug the exhaust, and close the carb. No rusting so far, just a little discoloration.

Jimmy

Fury Tempest 3D Fury Expert 60

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09-08-2003 12:55 AM  14 years agoPost 13
SteveO'

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St. Louis, MO

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Yeah Chris - I tried doing what you described. I used a Dave Brown CA applicator bulb and filled it up half way with Marvel Mystery Oil. I connected that to carb fuel inlet, removed the glow plug and cranked with my starter while squeezing that lube into the carb. It drew it thru the engine just like it was fuel, I'm sure it was atomized cause I had put a paper towel over the glow plug hole to catch any dribble and it looked as though it was sprayed with a fine mist... that's got to have given everything internal a good coating.

There are way too many posts here on RR about rear bearing rust and contmination. I'm going to start doing this with an OS70 that already has about 25 flights on it, hopefully there isn't any damage yet. I always run it dry at the end of a flying day.

I used to do this with my planks. Actually I use a 50/50 mix of Marvel and automatic tranny fluid. Don't know why, something I picked up long ago...

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09-08-2003 03:41 AM  14 years agoPost 14
irq

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San Diego, CA

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I have been reading this thread with interest as I have noticed the rear bearing in my C-spec getting some discoloration over time.

However, I have a question for you New Zealand/British guys.. what does "neat" mean in the context of "neat oil" or "neat fuel"?

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09-08-2003 03:49 AM  14 years agoPost 15
Secret Squirrel

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New Zealander living in Melbourne, Australia

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Over here, we have to mix the fuel ourselves. We buy the methanol, nitromethane and oil seperately then mix it together.

The coolpower here turns up as oil only (blue), not pre-mixed like what you guys have.

I expect that in this context 'neat' means something like an exact amount of oil as opposed to an amount of oil/nitro/methanol all mixed up together.

Si

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Simon Lockington

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HelicopterEngines Plugs Mufflers Fuel › Engine bearing rusting
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