The only time I've needed to take the engine apart is to clean the blackened castor off the pistons or ring grooves. Normally I just pull the backplate and glow plug. The blackened stuff may need some scrubbing to speed up the process. I use toothpicks, wood skewers and old tooth brushes where needed. What works for me is straight antifreeze without water and cook on low overnight...sometimes longer to get the burnt/black stuff off. I use all castor fuel and wait until the engines are really ugly before doing the crockpot. When I first started using the crockpot I rinsed the engines with glow fuel. Later I experimented with a junk Fox 40BB and let is sit out on the bench without rinsing...weeks. No rust or corrosion, even the bearings were ok. So I quit rinsing a long time ago. Some report their engines get discolored but it hasn't happened to me with dozens of engines. Also, antifreeze does zero cleaning if you don't have heat...tried that too.
Bill hit on some major points that some miss. When doing the crock pot thing, you want to use straight antifreeze with NO water. And only use the low heat setting on the pot. Antifreeze has rust inhibiters in it, so as long as you can drain most of it off and back into the pot, and good blast with an air gun, or wash down with any kind of safety solvent will clean it out of the engine if you are just doing plain bearing engines and such. I have taken engines and pulled anything plastic from them, did and over night soak in the crockpot, then drained it dry, blew it off, flushed out the crank case with a bit of fuel, the gave a short run on a test stand to clear it out , then mounted on a model. It just depends one what work you want and need to do on the engine. If the engine has bearings, they will be clean enough for you to get a good feel for their condition by rotating the crank by hand and if you need to replace the bearings, you are already half way there. I don't wash anything in water, even if I am doing a full tear down, just isn't needed.
Type at you later,
Dan McEntee
PS to add; Almost all antifreeze/coolant sold today is safe for aluminum. Most engines these days have aluminum heads or aluminum tanks and cores in the radiators and heating coils. Now, if you grab a jug that has been on the shelf in back of Grandpa's garage or shed, read the labels carefully!! You are on your own as far as that is concerned. And a crock pot full of straight antifreeze will probably last you a life time. AND ALWAYS DO THE PROCESS OUTDOORS!! Glycol fumes are pretty nasty!!