PDA

View Full Version : Serpentine Belt


JeepDad
07-17-2013, 11:39 AM
'97 XJ, 4.0L Has anyone had problems with throwing the serpentine belt. I've had this '97 for about a year. I've replaced the belt 3 times and have had to put it back on after being thrown probably 10 times. I've checked pulley alignments and checked for accessories binding but nothing obvious. Any help is appreciated.
Mudderoy
07-17-2013, 11:47 AM
'97 XJ, 4.0L Has anyone had problems with throwing the serpentine belt. I've had this '97 for about a year. I've replaced the belt 3 times and have had to put it back on after being thrown probably 10 times. I've checked pulley alignments and checked for accessories binding but nothing obvious. Any help is appreciated.

I've had my 1998 since it was new. I also have a 99 for a couple of years, never had this issue.

I'm wondering. You have to adjust the belt tightness right there above(?) the water pump, but you have to loosen (then tighten) the idler pulley just below the power steering pump. Could it be that the idler pulley was never tightened?

Hmmm also I did have my harmonic balancer come apart on me, I don't think the belt came off, but it that outside piece of the balance is walking around that might throw the belt.
JeepDad
07-17-2013, 12:14 PM
The adjustment for the idler on this '97 seems to be tightening just fine. Do you think anti-freeze getting on the belt would cause it to jump? I would expect it to make it slip maybe but not jump off the pulleys.
Mudderoy
07-17-2013, 12:15 PM
The adjustment for the idler on this '97 seems to be tightening just fine. Do you think anti-freeze getting on the belt would cause it to jump? I would expect it to make it slip maybe but not jump off the pulleys.

No I don't. I bet 4.3lxj or msmoorenburg will chime in shortly and have better ideas.
NW99XJ
07-17-2013, 12:24 PM
To me it DOES sound like a tension issue.
On some 4.0L's they did not come with a spring loaded idler pulley like these:
http://images.oreillyauto.com/parts/img/large/hdn/5884.jpg

instead they have a bolt driven tensioner pulley as seen here:
http://img.photobucket.com/albums/v702/xjohnnyc/Misc/serpbelt2.jpg

If you DO have an idler pulley, it may have the internal clock spring broken or worn, not providing enough tension.
If you have the other style, there's a chance you need to tighten things up.
4.3LXJ
07-17-2013, 03:21 PM
It is pretty tough to throw a serpentine belt. They have to stretch in order to do so. So my first guess is you have a dry bearing seizing up at speed on an alternator, AC or a power steering pump problem. The only time I threw one it was because of the power steering pump. Your AC wouldn't be overcharged would it?