I have an 89 F-250 with a 351. In the last 2 years I have replaced the Belt tensioner 4 times. The first one started squeeling and exploded after about a month. Iv tried using light viscocity lube, WD40, even soaking them in oil to make the squeel stop, but it wont work. I keep replacing them because I dont wont a repeat of the first. Is there something I'm missing that could be the cause of this? I do a moderate amount of 4 wheeling so I do spray then engine down sometimes to get mud off but its never on the front of the engine, could the water be doing this?