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Engine basics => Engine set up tips => Topic started by: Kim Mortimore on October 03, 2010, 12:23:10 AM
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My 24 oz OTS Ringmaster with OS20FP (or 21 for Dan's benefit) ABC/ABN(?) (Brett Buck setup which is unrelated to the problem), had previously run fairly well, maybe 85%--good enough for contests by my standards. During the last few flights the RPM started fluctuating both on the ground and in the air. The motor did respond to needle changes, though erratically, and there was no RPM drop when removing the ignitor (Thunderbolt RC long plug). I'm running Sig 10% with 20% half and half blended oil and 1% Randy juice added.
I tested the metal tank for leaks, cleaned out the needle body, checked the filter, replaced the fuel tubing and O-ring, silicon sealed the venturi/case seam and both sides of the needle body/case, and replaced the thrust washer which Larry "Eagle Eye" Wong astutely noticed was missing. No joy.
The sound of the motor was not right in addition to the erratic run, and the sound would change during maneuvers. After the last flight, I saw that the engine compartment and the underside of the nose were covered with black oil containing visible metal particles that had come out the front of the crank. My limited previous experience with black oil has been due to faulty or worn ball bearings, but obviously the 20 ain't got no ball bearings.
Any ideas? Thanks in advance.
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Sounds like you are missing the real thin steel washer that goes between the case and thrust washer. I have the same problem on a couple of my OS LA engines when I lost the thi washer. But in reality there has never been enough black with metal shavings to worry about for me as long as the engine is running right. This is my experience. H^^
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Kim
The black oil is most likley coming from something that is loose
look for loose motor mounts
loose muffler
loose backplate
anything aluminum rubbing will make the black oil
The thin washer mentioned above will do this too
spinners rubbing will make the black oil also
Randy
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Sounds like you are missing the real thin steel washer that goes between the case and thrust washer....
....and replaced the thrust washer which Larry "Eagle Eye" Wong astutely noticed was missing....
Hellllloooooo....
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Kim
The black oil is most likley coming from something that is loose
look for loose motor mounts
loose muffler
loose backplate
anything aluminum rubbing will make the black oil
The thin washer mentioned above will do this too
spinners rubbing will make the black oil also
Randy
Randy,
Thanks for the suggestions. It's all tight and doesn't have aluminum mount pads. I will show it Larry Fernandez, who built the plane, and see what he thinks.
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Kim
What color are the metal particles?
Brassy or silvery?
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Randy,
Thanks for the suggestions. It's all tight and doesn't have aluminum mount pads. I will show it Larry Fernandez, who built the plane, and see what he thinks.
HI
If it is coming from nothing on the outside m thats loose , chances are good it maybe coming from inside the engine, You should look thru the engine thoughly or have someone do it for you
Randy