ORIGINAL: opjose
ORIGINAL: mesaflyer
I pulled the engine (OS 55) out and at first I thought something had happened to it internally, because when I turned the shaft I could feel something rubbing inside. There was not prop on it. So I pulled the back plate off and couldn’t find anything wrong, except that the crank shaft has some in and out play to it. I bolted a prop on, and the rubbing went away, as did the shaft play. Does this sound normal to you guys?
I don't know for sure about the OS .55 but at least for the other 2C O.S. engines I have, there is a small washer behind the prop drive.
This small thin washer "pulls" the crankshaft forward a bit when the prop is screwed in.
With the prop off you feel the in/out play because the washer is not doing it's thing.
DON'T LOOSE IT! And make SURE that it is there.
Without it you WILL feel that "rubbing".
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That rubbing may also be the back of the crankshaft rubbing against the backplate. The crank may have been pushed backwards a little in the crash. When you bolted the prop on the crank was pulled forward away from the backplate.
If you check the washer make sure you don't loose that little woodruff key. No hardware store that I've seen carries the right size.