Radiator leak sealer barrs etc. damage.

Hi All,
So after pulling my heads off of my 273 I noticed that many of my coolant passages were almost completely sealed and the inside of the block looked a bright orange which I determined was just rust. It looked like some of the passages were welded shut which I thought was really strange. when I ran some steel Wool over the "welds" they crumbled away and revealed the coolant passage.

Is this due to the previous owner dumping Cooper-Seal/Barrs Leaks stuff? The blockages looked like solid metal.

Notice how the forward and rear cylinder have entirely plugged passages?




Thanks in advance,

Bill