This is the picture of the rear drivers side water jacket after pulling the intake. I just bought this motor and pulled the intake and this is what I found. It was caked at the surface and after digging out all the gunk (which felt like sand, and oil and tooth paste mixed together), it cleaned up real well. The gunk only went down about 1/2 inch.
Take a look at these guys. What would cause the rear water jackets to get all blocked up like this? Guessing bad seal on rear of intake? Front water jackets were clean as a whistle (this picture).
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