I suspect that the castor oil gum really is the culprit. If it was hydro locked it wolud have cleared very easily with no lasting effects (unless the con-rod bent).

Simmer it in antifreeze for ~12 hrs -- the goo will either be melted away or it will just brush off. The engine should be just fine after that.


The use of castor with ABC/N engines is a very good idea, as it helps protect against lean-run damage, & in the case of bushing engines like yours, it provides better lubrication of the crankshaft & shaft bushing. A periodic clean-up is a small price to pay.