i looked into this a few years back, the holes in red arent supposed to be open, i was told the holes are in the block to allow the sand when the blocks were cast to be washed out
i DID punch a head gasket out one time where you have the red and ran it BUT i burned up my number 4 piston, the way the water goes thru the engine it comes out the bottom of radiator into engine, thru the wp, flowing thru the block towards the rear of the engine where it comes up into the head and flows back towards the front
it is a slight side of the cylinder uptake where you see the water jackets around the block
I only run Toyota or Rock Product head gaskets
Thanks for the explanation about the sand and casting. It makes sense.
You write "burned up my number 4 piston" do you believe that was due to you punching additional water outlets? What is a burned piston? i've never heard of that. i've heard of a burned valve.
