00silver

Thanks sloride, but already tried that. I'm sure it's the idler, just not sure whats causing it. I think I'm going to exchange the belt for the more expensive one. it's the only weak link here. It can't be the pulley, I've replaced it twice & checked all the other ones.

Thanks YXMJ. I did buy the cheaper belt, could it be the cheaper belts don't hold up as well, or stretch. I know the routing is different on the older 4.0's than the newer ones.

OK, I'm new to CC, but not jeeps so I have a working knowledge of TJs XJs Zjs & other models, but not so much on an MJ & older xjs(pre 90). I bought my first one last week, and it's got some issues to say the least. I've searched naxja quite a bit, but the MJ section is limited, so here goes. I have a 1988 long bed lerado with 4.0 & aw4 auto & 4x4 (rust free). I have no interior lights or stop/ brake lights. I have checked at the fuses & replaced any that were blown, so that's out of the way. The turn signals half way work when the emergency flashers button is pulled out (I have no idea why). It seems as though some one at some point had amps & speakers in the truck due to the rats nest running from the fuse panel to the rear of the seat. I fear that's where most of my problem is. Next is the idler pulley, the belt routing on this 4.0 is different than any 4.0 i remember so maybe I'm missing something with older models. it has factory A/C so the idler pulley sits between the A/C clutch & top of thermostat housing. I can't get this thing to stop screaming. I have replaced the water pump, idler puller(twice), belt, and checked all the other pulleys & they turn smooth. The belt is not to tight or lose. If I spray PB blast on the back side of the ilder pulley it shuts up for a minute & then right back at it. Anything advice would be helpful. Thanks again.