Serpetine belt

Hi there,
I'm an actor, not a car guy so I'm kind of clueless.

I bought my first Jeep about 6 months ago - 2000 Cherokee 4.0
It's been running great but this summer it started to squeel when I turned on the AC. So I took it to my friend who's a GM guy (oops) and he tightened the serpentine belt. He said he didn't know what tension it should be and he hoped it wasn't to tight! I got in it and drove it home and now it runs very rough especialy at idle. It acts like the engine is lugged ?(is that a word)? and like it's going to die when at a stoplight.

What's the correct tension?
help....... :-(

Lee B said:

Hi there,
I'm an actor, not a car guy so I'm kind of clueless.

I bought my first Jeep about 6 months ago - 2000 Cherokee 4.0
It's been running great but this summer it started to squeel when I turned on the AC. So I took it to my friend who's a GM guy (oops) and he tightened the serpentine belt. He said he didn't know what tension it should be and he hoped it wasn't to tight! I got in it and drove it home and now it runs very rough especialy at idle. It acts like the engine is lugged ?(is that a word)? and like it's going to die when at a stoplight.

What's the correct tension?
help....... :-(

Click to expand...

According to the FSM it's 140-160 lbs-ft. This is when you use the tension gauge.

However if you have a seized idler wheel and then tightened the belt down that should prove interesting. Personally, I would have the belt replaced as well as the idler pulley. I'd also have the A/C compressor checked out. Something may not be right and you could be doing more damage. Also check out the harmonic balancer, thats the big bottom pulley at the very bottom part of the engine, it is a two piece pulley and sometimes the outer ring seperates from the inner ring that attaches to the crank shaft and causes all kinds of havoc.
Correct tension for a new belt [a new one is defined as one running less than 15 minutes] is 180lbs. A used one [more than 15 min] is 170lbs. Tells me that initially the new one stretches quite a bit in that first 20 min or so of run time.
Might want to check out one of the local vo techs or community colleges and take a nite course in auto mechanics, usually two nites a week and you will learn alot. Also the factory service manual, available from jeep, about the size of a good sized city phone book, has alot of invaluble information and how to's.

Push down on th belt in the center between two of the pulleys, the belt shoud "deflect" in layman terms: "move" approx. 1/4" as your push on it. If you push hard and it doesn't move at all chances are it's too tight. It should have a little give to it.

Thank you for the help. That gives me something to go on. Thanks