I inherited a Ford Explorer with a 3.5 engine. Very nice car, when it works.
Ford put the water pump inside the engine. I am not kidding. Replacing it is a major repair you can't do at home unless you're in the 99th percentile.
The water pump is expected to last something like 80,000 miles, or less than half the life of a well-maintained car. I paid $2,500 to have my water pump replaced, and it may fail again. Basically, Ford should have told every buyer, "The car actually costs $2,000-$3,000 more than you think you're paying, because the water pump will fail at least once."
A failed pump can send coolant into the wrong places, destroying the engine. Nothing like that was possible on my 1970 Buick.