So I have two Nitro planes in my fleet now and I've procrastinated doing anything with them for far too long.

What should one do to an Nitro engine that has been sitting idle for a while?

I seem to recall someone at the field saying there's something special to do prior to even turning the prop or else risk causing some sort of damage. I'm a litte fuzzy on what that might be.

The engines in question are an OS 0.91 on what was once Dewy's P-47. I presume the engine was well taken before I bought it almost two years ago.

The other is an OS .40 that's was on a small ugly zero that I picked up at Perry for $20. I assume it might need more attention and have been reading stories of cooking them in antifreeze or using carb clean + singer sewing machine oil to clean it up.

Any other general advice on these two engines?

Pour some after run oil, or Marvel Mystery oil in the carb and turn them over in order to suck that stuff inside the engine. Any other stories are generally related to unfreezing them. Oil up like this, they should be able to sit for years.

You shouldn't turn the prop if they've been in a wreck. (I have an OS .46 LA from the Kadet Senior that's in this state.) In this case, turning the prop can suck in the dirt that inevitably ends up in the carb after a crash. In this case, disassemble the engine, carefully clean the dirt away, and then go back to paragraph one. In my case, I plan to remove the carb body, thoroughly clean the exterior of the engine, oil things and re-assemble. Since the muffler is still intact, the carb is the only entry point for dirt, so I don't need to do anything else.

What Nergall said plus I always recommend removing the glow plug before attempting to rotate the crankshaft. That minimizes resistance so you can better feel if there is any grittiness. If there is then STOP immediately so that you don't score any of the internal mating faces and then disassemble to clean.

It's not hard - there's really not much to them. Common sense and a little patience is all that is usually needed.

Thanks guys! Not rotating if there might be dirt is the point I was missing and I appreciate the other tips too. I'm going to disassemble and clean the OS .40 since I have no idea if there might be dirt or not and it'll be good experience before playing with the P-47.

Are there any parts that might need replacing other than the glow pug? My shopping list right now is after run oil, #8 glow plug, a glow plug wrench, and a new battery for the glow plug igniter.

For normal use, just props and glow plugs. For restoring a very old engine, it might want new bearings and if it even has one, a new piston ring. Those parts do require some care to replace though. Not sure if I wouldn't just send it off for that level of repair myself.

Oh, on four strokes, every once in a long while, you might check the gap on the rocker arms.

Couple of tips...

Be careful during disassembly to not tear any gaskets or O-rings. If you accidentally damage one then replace it.

If you wash anything out with alcohol then wash it again with glow fuel or after-run oil (I use Marvel Mystery oil) to avoid things drying out and/or corroding.

During re-assembly, don't over torque screws into aluminum or you might strip the thread out of the housing. Better to clean the screw (with alcohol), apply a little blue threadlocker, and install to a moderate torque.

Blue thread locker is essentially useless on any engine part likely to get hot.

Not true. That only applies to the muffler screws. Hi-temp RTV works better for them.

The is the best for glow engines.