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HelicopterEngines Plugs Mufflers Fuel › Chrome coming off engine bearings...
09-03-2003 09:59 AM  14 years agoPost 1
Petrolburner

rrNovice

Wellington NZ

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We have been examing some OS 91SXH bearings that have been in use for a while and have found some things that concern us.

The chrome seems to be disolving from the exposed (ie exposed to the fuel/air mixture inside the crank case) surfaces. Surfaces which are not exposed, (ie in the seating surface of the outer diameter) seem fine.

We run 10% nitro, 15% Coolpower Synthetic oil, the rest methanol which has 2% acetone.

We have taken a picture of this to illustrate our point.

The bearing itself is not failing other than the degradation of the chrome on the balls and exposed metal surfaces.

We believe that it could be fuel related, but what component? ie oil, methanol, nitro or acetone?

FYI: This bearing is out of a C-Spec which would not yet have done 80 flights, it generally flies each weekend. It is not normally run dry at the end of each session, and does run an MPII.

Anyone have any ideas?

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09-03-2003 02:13 PM  14 years agoPost 2
DS 8717

rrProfessor

Here wishing i was somewhere else

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That's one of the nastiest bearing i have seen in a while. First 15% good oil not enough let alone coolpower trash. Second the balls are not chrome plated, yours are totally rusted and pitted from the rust. My guess is the piston and cylinder are probably not in very good shape either with all that trash running through the motor.

You need to start running your motors dry at the end of the day,and a little after run wouldn't hurt either.
People at my field used to ignor my running my motors dry and putting castor oil in the glow plug hole untill they trashed their motors, Now they at least run them dry.

YOU ONLY LIVE ONCE..IF YOU LIVE IT RIGHT THATS ALL YOU NEED

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09-03-2003 05:45 PM  14 years agoPost 3
hpilotrc

rrVeteran

NY--->>Mooresville, NC USA 8/2005

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That bearing has to be replaced NOW.

Run you fuel out of the engine by disconnecting the fuel line and leaving it disconnected.

Use a after run oil and make sure the oil gets into the crankcase. I add Mobil 1 Synthetic ATF thru the glow plug hole when I am done for the day....holding my heli in a position so that the oil slips into the crankcase thru the cylinder liner openings.

Be sure to take out the plug and using the starter run the oil out of the engine (with throttle open) before trying to start the engine...otherwise you will have hydra lock and damage the rod.

Michael

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09-03-2003 08:15 PM  14 years agoPost 4
Secret Squirrel

rrKey Veteran

New Zealander living in Melbourne, Australia

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That's a bearing that has come out of one of my C-Specs after about 80 flights.

The bearings AREN'T covered in rust, it's a coating of some film or something that comes off fairly easily with a rag.

The piston and liner (and indeed the rest of the engine) look absolutely fine. It just seems to be affecting the bearings.

-------------
Simon Lockington

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09-04-2003 09:53 AM  14 years agoPost 5
helispanker

rrNovice

Sweden

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After running the engin dry turn it backward so the piston and cranshaft close the openings to the crankhouse. Also put the carb in lowest position.

Robert

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