When you turn the prop by hand it really is hard to turn over even with no glow plug in it. It feels like oil has congealed around the bearing or on the cylinder wall. There is no scraping or grinding noise -- it is just stiff to turn over. The engine was given to me, I suspect regular oil was used a few years ago when the engine was put up and it just sat there all this time. Is there anyway to clean this out without disassembling the engine? Thanks for any input.

Easy way to clean is to just pour in some alcohol (rubbing, denatured, Bacardi 151 , etc) and turn it over some. The alcohol loosens the old congealed oil quite well. Once it's turning freely and the alcohol is coming out clear, put the engine in the oven at 250-300 degrees for about 10 minutes to evaporate the alcohol. Take it out (use a pot holder, oven mitt, etc) and oil it up. Note that you should also check that the needle and spray bar assembly aren't clogged up.

You can put some oil in the carb, glow plug hole and the exhaust port and keep propping it over. If the engine is mounted on a plane and ready to go, you can put fuel in it and prop it over few times. As for an oil, you can use Marvels mystery oil, 3 in one oil, gun oil or sewing machine oil. Good Luck, Dave

if you put this in the oven you shpuld remove the nylon throttle arm from the carb so it does not distort

Thanks for the info, I put some alcohol in the engine, turned it by hand quite a few times. It seemed to be better. Then I took the "plug" off the back of the engine and poured some alcohol in there and now it is soaking. Some of the "gunk" is seeping out the front of the engine. Maybe by tomorrow it will be better...

If you put it in the oven, take off the carb and any rubber/plastic parts.

sounds like its been left with castor oil/fuel in the crankcase, if its already mounted in a plane it may be easier to fuel it and start it up with an electric starter, then leave it running low-mid throttle range and give it a few revs, this should clear out the castor oil and get everything moving the way it should again. (worked for my old OS MAX 35)

NOT a good idea. Any congealed oil will not allow fuel, which contains fresh oil, to get to the bearings and other needed surfaces. You could damage bearings and score surfaces before proper lubrication has re-established.

well scratch that idea mate!

i use the alchol method as listed above or soak it in nitro for a while (i doubt it will be in there long enough to do any corrosion damage, but it will help free the bearings and innards, i had to do this with my carb once...)

For corrosion to occur there has to be Oxygen (air) present. If the engine is submerged (under) in alcohol then air can't get to it. Therefore NO corrosion. Once out of the fluid it needs to be cleaned, dried and re-oiled as quickly as possible.

And for the chemists out there, yeah I know there is oxygen in alcohol but not active to the corrosive degree. You can also soak it in fuel if you want, that works fine. I save old stale fuel for that.

HOPPES gun cleaning solvent is the best degummer and devarnisher I've ever tried.

Free at last. The engine finally "let go" and now spins freely. The alcohol soak (I took the back plate of the crankcase) around the front bearing and connecting rod (two days worth) did most of it but after that I soaked the crankcase in glow fuel and that seemed to really loosen things up. I was able to start it and run it on the test bench tonight for about 15 minutes. Thanks for all the help. It's going on a little fun fly soon.
Bob