Bought my 92 4WD MPV new and have put 115k miles on it. Love it to death, but it now eats up timing belts almost as fast as I replace them (VERY expensive trend). My mechanic says something in engine is causing the problem but he can't locate it. Last time this happened the belt slipped, throwing the timing way out and the belt shredded itself by running on the rim of the pulleys. I was in mountain country with no cell service and nearest town 40 miles away, at night. Luckily I was able to drive into civilization because this is the one time the belt did not simply slip off the track altogether. Is there something inherently bad about the 6 cyl 3.0L engine on this car, or is there an easy fix other than motor replacement? If I replace motor, am I going to end up with same problem? This has always been a weakness in my car as the first time it happened the car was only about 6 months old.

It is not the engine. There are 3 idler bearings,1 tensioner and 1 tensioner bearing bushing. You need to replace them all probably. Make sure the spacers are there also for the top bearing. A worn bearing will make the belt track wrong and wear the edge of the belt til it strips or breaks. The bushing on the pivot of the tensioner bearing is also critical. There were some modifications to the bearings later on so buy factory from Mazda or you will never get the updated bearings.