Volture
The best method I have found is to get an electric crock pot slow cooker and fill to cover the engine in question . Start, by removing the glow plug ,the prop ,and the muffler. You can put all the parts back into the crock . The cooking solution is half water and half automotive antifreeze[ethelyn glycol ]. Let for 24hrs. and simply wash off with hot water. When dry , lube with oil to protect the bearings . The nice thing about this method is no dissasembly is needed or required. Also the out side of the engine will look brand new. try it you will like it.
tom