I dont know if this is common or even somthing to worry about, but my lower cooling pipe had a badly warped bottom flange and because of this it leaked when coolent was put in. To fix this, I tried to remake the gasket with a thicker material to remedy the un-even surface but when i started tightening it down, the flange snapped. P.s I also tried to lightly file the surface to get rid of the divit, but was a afraid of taking to much material off and having a huge "equal" gap.