Locknuts on 4-stroke engines

Grr.

I went to take a look at one of my projects on the backburner today: An O.S. .52 four stroke engine slated for use in an edge 540 RC plane.

On most four stroke engines, there are two prop nuts: one to secure the prop, and the other to lock the first prop nut in place.

Mine, however, has one prop nut and a screw-on harry higley style spinner. Same principle.

I was replacing the wooden prop with a plastic one, since the engine seemed to have trouble maintaining idle as well as a few other issues - the wood prop was too light.

To my surprise, I just couldn't remove the spinner with the typical screwdriver through the little hole. I put it in vise grips and put enough force on it that the wood prop broke in my hands, since I was using it for leverage.

Then the prop started slipping on the drive plate, meaning I couldn't get any leverage from it.

I finally got it off by putting the spinner in a table vise and twisting the drive plate with vise grips. The spinner and prop nut were locked together until I had enough room to get a wrench in there to break it free, which is what caused my issue in the first place.

I don't thing that the engine is damaged, but I'd still rather not have to put things in a table vise to get them loose.

I wonder why it had locked so thoroughly? The prop had been there for a very long time, I bought the plane it came on from my LHS that had it on consignment. Still, I've never seen one that tight.



Proved to be quite a headache. Not to mention my now-bent screwdrivers...