The thing that the water pump bolts onto

“It is possible to put the longest bolt in the wrong hole and drive it into the outside of #1 cylinder and to crack that cylinder, sending coolant forever into that cylinder.

If a cylinder is cracked and getting coolant in that cylinder, won’t the car run rough? Would not the compression in that cylinder be low due to the crack?
Thanks.[/QUOT


Water/coolant doesn't compress. Anything more than a shot glass full (depending on head and piston) will break a piston or bend a rod.