Original never rebuilt 62,000 mile engine. Freeze plug leaked so I removed it and found a ton of thick brown sludge in the cooling passages, nearly blocking them. Had to dig the sludge out with a screwdriver. 4 previous flushing had not touched it. Too thick, too well wedged into the nooks and crannies. Now I know why the car gets so hot on 90 degree days after an hour. Resticted water circulation! So...... short of removing the other freeze plugs and digging it out, has anyone else come up with a easier fix?