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Prop Nut Loosens

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Old 02-20-2012, 10:33 AM
  #1
Flysfloats
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Default Prop Nut Loosens

I have an OS .61 SF engine that has given me great service TILL now! I can not start the engine because the prop nut loosens up with the first or second flip of the prop. I am running Cool Power 15%, I have added an abrasive "washer" behind the prop. I simply can not tighten the nut tight enough to prevent this from happening. Your help is despartely needed, Thank you. FF
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Old 02-21-2012, 06:50 AM
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Default RE: Prop Nut Loosens

Usually, if the propeller nut loosens when the engine is running, it means that the propeller nut isn't tight enough. However, if the propeller cannot be tightened enough, you may need to try a different propeller. It may not be able to be compressed enough to hold the nut properly-tight. You may need an abrasive washer between the prop nut and the metal prop washer, and between the metal prop washer and the prop.
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Old 02-21-2012, 09:22 AM
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Default RE: Prop Nut Loosens

Bax:Another day and another frustrating attempt to start this engine. I switched to a wooden prop, put abrasive drywall grid washers on both sides of the prop, am not using a spinner so no backing plate, tightened the nut as tight as possible, AND even with just a small squirt of fuel into the carb and NO glow igniter, I flipped the prop over a few times and the nut loosened.

I then retightened the nut, finger over the carb and turned prop over to prime the fuel line, put a small amount of fuel into the carb, and then tried to flip backwards. Would get a small pop but no indication it wanted to run either direction.

I even cut small hatch marks on both sides of the prop hub to try and get more grip on the washer/nut. What is next???
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Old 02-22-2012, 07:13 AM
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Default RE: Prop Nut Loosens

You may need a new propeller nut or a new crankshaft. You could try using two nuts, but that should not be needed for most two-stroke engines.
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Old 02-23-2012, 07:30 PM
  #5
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Default RE: Prop Nut Loosens

Well good news, with your support I got the engine running today!! A tech from OS engines/Hobbico also suggested using Lok Tite. After using a Master Airscrew and wooden props, I went to an APC prop, added my abrasive washers, cleaned the threads, and added Lok Tite. Let it set up overnight and this morning got a successful start and run. I hope that this proplem is behind me. Thanks to all that responded. FF
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