Expensive? Yes. But before you dismiss that option, first account for the real costs of a rebuild. “When people talk about rebuilding an engine, they usually mean rebuilding the internals—new pistons and rings and so forth,” says Muessel. Too often, he says, they forget to tally the cost of all the auxiliary parts: the starter ($400 to $800), alternator ($400 to $800), heat exchanger ($1,200), and saltwater pump ($500). Add a wiring harness, engine gauges, switch panel, transmission, and injection pump, plus labor, and the costs of a rebuild start to compete. It’s not uncommon, Muessel says, to spend 60 percent of the cost of repowering on a rebuild. And you’re still left with an older engine that’s long out of warranty.