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More Power
02-25-2013, 14:14
I received the following email this morning about an ongoing accessory drive belt problem. I thought some here might either benefit from the information or might have a different solution. Your thoughts....



After about 5 belts and 3 vacuum pumps on my 1996 GMC with 6.5 diesel, I have finally solved the problem as follows.

Remove the tensioner and note the limit stops for the pulley mount arm.
Grind about 3/4 inch of the limit stop that keeps the tensioner pulley from being raised further.

Re mount everything except this time use a 100 inch belt instead of the 101 as per factory specs.

What this does is prevent the tensioner from "locking-over", preventing extreme tension on belt driven components. As noted earlier, 3 vacuum pumps had to be replaced as well as an alternator (bad bearing) and A/C pump for the same reason. Hope this helps someone.

dixiepc
02-25-2013, 14:45
A picture would be a great help.

DennisG01
02-26-2013, 07:09
Interesting. This sounds like the problem was possibly related to a defective tensioner? Or am I reading into this too much?

More Power
02-26-2013, 11:40
No pics available... I suspect something is going on that isn't apparent - i.e. the tensioner is over-rotating because the belt was a little too long because one of the pulleys is too small.

Has to be an odd situation, because this isn't something that's come up before - that I remember. Jim

kuhlrover
02-27-2013, 13:45
I recently changed my serpentine belt. NAPA had 2 different part numbers for my 1998 truck. One belt was about 1/2" to 1" longer than the other. They said it all depends on if I had the 120amp or 105 amp alternator. I could see where it is possible to get the wrong size belt since both work with the same accories. With the alternator on the truck, it is not easy to tell what size alternator is on there. I guess it is also possible that the alternator pulley size was changed.

Tim


No pics available... I suspect something is going on that isn't apparent - i.e. the tensioner is over-rotating because the belt was a little too long because one of the pulleys is too small.

Has to be an odd situation, because this isn't something that's come up before - that I remember. Jim