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whiteoaks 10-31-2010 01:49 PM

Would appear I am getting close to having to replace the lower idler pulley on my 92 Wrangler, 4.0-6cyl, w/AC. I have heard some sqealing on infrequent and intermittent occasions when I first start my jeep up. I have replaced the upper idler pulley before and that was pretty simple. This morning I loosened the serpentine belt and spun both pulleys. Upper pulley felt and sounded smooth. When I spun the lower pulley it did not feel smooth like there was much lube, if any, in the bearing, and I could hear the balls in the bearing clicking. I did not though, feel any roughness or grinding when turning the pulley so it would appear that there are no serious or extreme flat spots on the balls themselves. So, I am 99 percent sure that I need to replace the lower bearing in the not too distant future.

Here is my question??? :confused: It looks like there is a long mounting bolt for the lower pulley also goes through the pulley bearing, thru the flange of the timing cover, through the lower arm of the AC mounting bracket and is then nutted at the end of that bolt. In other works the bolt is not bottom threaded into a flange or bracket like the upper pulley. Am I correct in my assumption? If so, what is the easiest way to remove that bolt as my Chilton doesn't address this task. If the bolt and nut combo is the fastening device, once I get the nut off (easier said than done), will the bolt slide out easily (along with pulley) or can I count on the bolt being bound up by offset alignment pressure from the AC bracket and the timing cover flange holes? Not much room to work from the back or underside of the alternator to push the bolt forward and I am dreading the though of having to remove alternator and AC (not disconnecting hoses):banghead:.

Can any of you experts that have tackled this job give me helpful responses as to whether, First - Am I correct about how the idler pulley is mounted and Secondly - What steps would make replacing the pulley easiest??? Thanks for any experienced help you can offer!!!:)

rushtone 02-04-2013 10:27 AM

Did you ever resolve this?

I've had similar intermittent squealing from my '94 YJ with A/C (4.0 6 cyl). I have replaced the water pump (due to leak), serpentine belt, and upper idler pulley. Using a mech's stethoscope it sounded like the upper idler pulley, but that didn't change anything. Squeal is intermittent, seems that cold weather is one factor (doesn't squeal when it's warm), and when it is squealing A/C on or off makes no difference.

When none of that did the trick, I went for the lower idler pulley. Wouldn't come out. It FELT like there was a spinning nut behind it, but I saw the bolt go into the timing cover and assumed, like the upper pulley, it was tapped in and I guess didn't look far enough back to find any nut. I concluded that I had stripped the threads on the bolt and would need to at least replace the timing cover, which did not make my day. As a short-term fix (and diagnostic aid) I put on an A/C-less belt, bypassing both idlers and the A/C compressor.

This is great news that there is a nut back there somewhere....


whiteoaks 02-05-2013 08:27 PM

No, never did. I tried repeatedly to break the bolt and nut but too tight, too much for one guy. Couldn't get either to budge. Thought about putting some heat from a torch on it but that seemed a little extreme at the time. Shot a little WD40 on the back side of the bearing (with the belt off), put the belt back on and it hasn't squealed again. I have 208,000 miles (all original) on the old guy and expect that some day I will have to deal with the lower pulley. Knock on wood it will last until I retire it. The nut is there I assure you or at least on mine 92' it is. If you ever have to do the removal send me a note on how things went will ya? Later

rushtone 10-08-2013 02:40 PM

Finally replaced the lower idler yesterday. It was in the process of doing a more thorough R134 conversion, so the A/C compressor was already off. Once the compressor was out of the way we* didn't have any particular trouble (*brother-in-law with A/C experience (and more motorhead experience than I) helping me out).

Any luck with yours? Or is the WD40 holding up?


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