I removed the water pump and poured CLR into the hole letting it run to the back of the block (where the crud is) and left it there 2 days. After that I drained it, neutralized with baking soda dissolved in water, washed out lots of junk, blew air at about 50 or 60 psi when the rinsing water was in there (reverse direction). Caused more crud to come out...some of which was about the size of a bb or smaller. My question: is there a better acid...something that would dissolve the old crud better or should I repeat with the CLR and leave it much longer?
Jon

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end