Homebrewer
Get an old crockpot, fill it with a mixture of antifreeze and water. I prefer 60% antifreeze, 40% water. Add ingredients-engine-and seasonings to taste (just kidding), simmer on heat for several hours or until castor crud is loosened.
Do this outside for fume relief. Typical antifreeze is toxic if ingested and make sure you take necessary precautions to protect small children and animals.
Once you are done cooking your engine and it is cleaned up, make sure you do your best to dry engine out completely and apply a light oil to prevent rust. I normally like to bath my engines in a hot solution of water and Cascade dishwashing solution after boiling them in antifreeze. After doing this, I then dry them out with a blowdryer/paper towels and apply oil.