The Ford 2.8L V-6 in the Mustang II Horsepower Zero of the mid-to-late 1970s. I was always stuck changing the water pump whenever one of them came in. The 16 little bolts would break in the block and the cheap timing chain cover would warp. After a while, our service managers would send them to the Ford dealer because we lost too much labor on fixing those things.
Have an uncle who owned a pristine mustang from 82 or 83 had the useless 2.8 v-6. He actually ordered a reman 2.8 it was still useless! Except this reman always had valvetrain noises that never went away. Total blue oval trash!