In our opinion, there is absolutely no reason to replace the engine in a Eurovan preemptively. Just about the only thing that goes wrong with these engines is the timing chain. We recommend replacing the timing chain if/when the transaxle gives up the ghost—since the transaxle has to be removed to do the timing chain job, you might as well do it then.
Barring timing chain failure, overheating (blown hoses or failed fans), or lack of lubrication (hole in the oil pan), these engines will typically go at least 300,000 miles. I have a 1997 with over 300K miles on it—it uses zero oil, makes no noise, and literally runs like it did when it was brand new. Awesome!
President, GoWesty Camper Products