1998 grand cherokee zj belt tensioner

98zjstroker

98zjstroker

Well-Known Member
Joined
Oct 14, 2009
Location
concord nc
So I believe my belt tensioner is going bad.....well at least the long bolt on the back of the mount bracket. My serpentine belt has now come off twice within a week. Each time the bold was loose. I just recently replace the belt so I'm thinking that when I did that the bolt had enough. At first I thought maybe I didn't tighten it enough but this last time I made sure and it did it again. My question is every place I have looked to get the tensioner/bracket does not have it. They keep pulling up a spring loaded belt tensioner that won't work. If I can just replace the bolt that would be great but not sure if that is an option.

Anyone on here no were I might be able to find the correct tensioner? (autozone, advanced, oriellys don't have it). Even ebay didn't have a Chinese knock off would work
 
Dorman 917-951?

917-951-007.JPG


You're tightening the bolt through the pulley after setting the belt tension with the longer bolt, correct? That shorter pulley bolt is what actually keeps the belt from loosening, and the longer bolt is to set the tension. To change belt tension, you loosen the pulley bolt, rotate the long bolt to set tension, and re-tighten the pulley bolt. If you're not tightening the pulley bolt, the longer bolt will vibrate loose as the only thing keeping it from rotating is the tension of a fluttering belt against the thread friction. Well, that and the pulley will eventually fall off.

So if you're having problems, look first at that shorter bolt through the pulley, or the threaded block that it screws into, and make sure you have the proper spacers or whatever are supposed to be used with that pulley hub.. I suspect someone has damaged the threads in the tension block or pulley bolt at some point in the 20 years since it was new, probably from over-tightening.

This is a very common type of tensioner design used on many makes/models of engines, it's dead simple.
 
Last edited:
Fabrik8 said:
Dorman 917-951?



You're tightening the bolt through the pulley after setting the belt tension with the longer bolt, correct? That shorter pulley bolt is what actually keeps the belt from loosening, and the longer bolt is to set the tension. To change belt tension, you loosen the pulley bolt, rotate the long bolt to set tension, and re-tighten the pulley bolt. If you're not tightening the pulley bolt, the longer bolt will vibrate loose as the only thing keeping it from rotating is the tension of a fluttering belt against the thread friction. Well, that and the pulley will eventually fall off.

So if you're having problems, look first at that shorter bolt through the pulley, or the threaded block that it screws into, and make sure you have the proper spacers or whatever are supposed to be used with that pulley hub.. I suspect someone has damaged the threads in the tension block or pulley bolt at some point in the 20 years since it was new, probably from over-tightening.

This is a very common type of tensioner design used on many makes/models of engines, it's dead simple.
Click to expand...

thanks I know how to do it but for whatever reason the belt keeps coming off. I ordered that part through advanced. No one else had anything for it online and the people who worked at the parts place have never heard of that tension design. Hopefully the new kit will fix the problem.
 
That subie ac tensioner is stupid, plastic, really? Seen a few break before. Like fabrik8 said, very common design. Especially prior to 2000.
 
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