On a passenger car engine, a rebuild usually requires machine boring of the cylinders, honing; matching of oversize pistons and rings, etc. Never thought too much about it. Then, as I learn more about machinery, I learn that most heavy duty diesel engines have you REPLACE the wear surfaces with new ones on a rebuild–not just “wet sleeve” design, but Detroit Diesel sleeves, for example, are removed, new ones installed, and put back in service that way.
It just seems a better system overall: build tolerances are those set by the factory; you aren’t limited to a finite number of rebuilds; the need for specialized engine rebuild machinery is lessened (making the job potentially cheaper due to not needing to send so much work out).
Does anyone know why? What is the downside to just replacing all wear surfaces? Cost or something else? (Is it an implicit indication you aren’t really expected to rebuild a gasoline engine?)