Two problems related to coolant leaking have been reported for the 1998 Plymouth Grand Voyager. The most recently reported issues are listed below.
Intake or head gasket leak allowed the crank case to fill with water and coolant. The engine immediately seized up and died. I was driving down a crowded interstate at the time, and lost all power, steering and brakes. The entire engine will have to be replaced.
Rear head gasket leaks coolant to rear of engine. From what I've now read, this was an unwritten recall, which Chrysler would fix if brought in before ~75--80k miles. Mine developed this leak before that, but I didn't find out about it until the vehicle had 105k on it.