rad Shop
Just did this job on mY Yanmar 2gm. Took off ther exhaust manifold and mixing elbow and took them to a local radiator shop. They did an overnight soak in their hot tank and got them squeaky clean. The bath discolors aluminum though. The result is the the smoke is gone. Theres lots of info the archives. There are 2 bolts holding the elbow to the cylinder head, undo these and remove the flex hpses.
