YUP.... LOL. Pulled the block plug out of a /6 that had seen 3k miles in about 30 years, and nothing came out..... the gunk in the bottom of the cooling jacket was about an inch deep..... Poked my pinkie in and wiggled it a bit and finally got some old coolant to come out. Flushed and flushed but did not get it all out. Had the block rust tanked at rebuild time, and the new coolant still turned rusty in < 1 k miles. It can take a lot of work to get them cleaned out.
