Homelite 25 Problem
 

Ran my Homelite 25 for the first time in quite a few years. Noticed afterward the prop hub had separated from the engine. There is now a gap of between the engine and prop hub of 1/16th to 1/8th inch. Is this just a case of the prop hub coming loose? How could this be? Doesn't running the engine actually tighten the prop hub? What else could have caused this? I had a smaller prop on than I should have and maybe it was running at too many RPM's. Any thoughts?

The main bearings may be going bad?

There is no endplay in the crankshaft so I'm leaning towards a problem with the prop hub. Which way do the threads go? Could it just have backed off?

Standard right hand threads. I would probably remove the prop hub and check things out. You might have to heat it a bit to get it started unscrewing, but Don't get crazy with the heat as there is a rubber seal behind the front bearing.
You could also easily pull the back cover off and inspect the rear bearing. Those are the only two things that could cause your problem.

Thanks Aviator, I'll try that.

Prop hub wouldn't budge. I tapped the crankshaft and it moved back into place. The whole crankshaft must have slid forward somehow. Very strange.

I will probably happen again as the crankshaft will slide forwards when pulled by the prop.
In the original application this was not an issue as there was no pull forwards.
Easy fix if you install a small washer/spacer between the crankshaft and rear bearing.

I was restraining the plane and running the engine really hard. I think if I just fly the plane, it will all be okay.