How long does a semi engine last?

If it's properly maintained, it should last a million miles (eight years) with no huge problems. A lot of guys who are real good about having their maintenance done can get a million and a half out of one.

These engines are made differently than are car engines--they've got liners in the cylinders, liners in the crank tunnel and so on--so they can be rebuilt to be as good as new. There are diesel blocks that were cast in the 1950s that are still in service.


I know of a Detroit Diesel 12V92 that's in a generator set in Yongsan, Korea. They installed the engine in the mid-1950s, it's running to this day, and they've never even had the heads off it.