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....
David
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....
David