cracked cylinder wall
 

i have a 98 k1500 the shop i'm dealing with says i have a cracked cylinder wall on #6 cylinder and is not repairable.I have good compression in 170-175psi # 2 4 and 6 no coolant leaks or oil leaks no coolant in oil no oil in coolant no smoke and don't burn oil all new fuel injection.This assesment just don't sound right to me,seems like if i had a cracked cylinder wall it wouldn't hold compression during the test and if cracked then there would oil in my coolant or coolant in my oil.I need help advice any one please.