Super tiny pin hairline hole fixed with JB Weld. I'll let it sure until after lunch and fill up and give it a test run.

 

A crack that low needed to be fixed. Your coolant level should be between the lines when cold.

 

I drove it back from Orlando (over 700 miles) and the coolant level was only about an inch and a half above the hose on the bottom of the tank. The owner said his Ford friend tech guy said you get much better flow with it just above the expansion hose. I really don't know. I figure they wouldn't have put the fill marks there if that wasn't the best place.

 

Was it low when you got home? When the coolant heats up it expands and goes into the expansion tank. It could have leaked out then and been low when it cooled down. Your right they wouldn't have put the marks there if it was better to have it lower.

 

looks pretty good to me. Go heat here up and see if she holds.

 

it'll hold, i've repaired 5-ton blocks with jb weld before

 

I hope it holds. I know that when I fixed a "plastic" coffee mug with JB weld, it held for a while, but the expansion/contraction due to heat fluctuations eventually made the joint fail. But, the material was much more rigid that that of our coolant boxes, so it may not be as detrimental to your application.