It’s a bad day when while driving on the hottest day of the year, your air conditioner suddenly fails, you try and slow down to pull off and see what is wrong and discover that you have no brakes, and pulling off of the road is like wrestling a steer on the way to slaughter and your voltage indicator drops from 16 to 12volts.  This weekend while returning home from the lake, I encountered this scenario.  I immediately knew what the problem was, the serpentine belt had failed.  The only surprise was the loss of vacuum assist braking, somehow I don’t remember that from my earlier experience with a serpentine failure on an auto.
So today its off to pick up a new belt, but before doing that I will check the pulleys and all of the devices attached to the serpentine to make sure the problem isn’t a seized alternator, vacuum pump, idler pulley or compressor.  I appreciated that diesel more after this experience. Dual batteries maintained voltage for the long ride home. brakes functioned with an incredible amount of leg power on my side. Power steering was powered by my arms and I was able to limp home where I could more easily fix the truck.  Had it not been Sunday afternoon I would have driven to the local shop and let them replace the belt, but that was not an option.  The biggest question now is did the belt fail due to age and normal wear or due to a seized device that caused an immediate failure.  Interestingly, there was no loud noise when the belt failed. Even with the big diesel being noisy, I would have expected to hear the sound of the belt coming apart and wreaking havoc underneath the hood. There was no destruction of hose or wiring that I could see.
But from past experience I will look more closely this afternoon to make sure I didn’t overlook anything. I had a 96 Grand Cherokee with a belt failure and I had the local shop replace the belt. The next day the belt failed again. Only then did the mechanic realize that the the idler pulley had seized. Idler pulleys are inexpensive and usually easy to access for repairs and if they seize, the belt will not last very long.
