Hey guys,
I'm having a strange "groan" coming from what sounds like the rear of the Jeep. It's been around for a few years but getting progressively louder the last few weeks and gotten to a point where I feel needs to be fixed. It's a 95 XJ with the 4.0, auto trans (AW4), NP231 and the Chrysler 8.25. Stock height.
- Starts at about 5 mph and gets louder at about 30-35 and then quieter again at higher speeds
- The sound gets louder as I make a big swooping turns (both left and right)
- Pitch of the sound gets louder as I step on the gas. If I coast it gets quieter (but is still there)
- Sound still happens with either transfer case or transmission in neutral
- The sound is louder on warm days and quiets down when ambient temperatures are cooler
- The sound is consistent with the rotation speed of tires, so sounds like something in the drive-train after the transmission
What I have done:
- Replaced wheel bearings with no change in sound
- Replaced driveshaft U-Joints with no change in sound
- Opened Diff and inspected everything. Looked good, fluid was clean and replaced with heavier 80W-90 quality gear oil and zero change to the sound
- Replace drums, pads and all brake hardware
- Lifted rear of jeep and checked drive-train with stethoscope. Could not identify any rubbing, grinding or weird sounds
- Spun driveshaft by hand and everything is smooth and solid
- Checked transfer case fluid
Any thoughts? Hints on what to troubleshoot further? I am at a loss and don't know how to proceed without spending big money to replace things like the entire rear end, etc. Many thanks for any help!
I'm having a strange "groan" coming from what sounds like the rear of the Jeep. It's been around for a few years but getting progressively louder the last few weeks and gotten to a point where I feel needs to be fixed. It's a 95 XJ with the 4.0, auto trans (AW4), NP231 and the Chrysler 8.25. Stock height.
- Starts at about 5 mph and gets louder at about 30-35 and then quieter again at higher speeds
- The sound gets louder as I make a big swooping turns (both left and right)
- Pitch of the sound gets louder as I step on the gas. If I coast it gets quieter (but is still there)
- Sound still happens with either transfer case or transmission in neutral
- The sound is louder on warm days and quiets down when ambient temperatures are cooler
- The sound is consistent with the rotation speed of tires, so sounds like something in the drive-train after the transmission
What I have done:
- Replaced wheel bearings with no change in sound
- Replaced driveshaft U-Joints with no change in sound
- Opened Diff and inspected everything. Looked good, fluid was clean and replaced with heavier 80W-90 quality gear oil and zero change to the sound
- Replace drums, pads and all brake hardware
- Lifted rear of jeep and checked drive-train with stethoscope. Could not identify any rubbing, grinding or weird sounds
- Spun driveshaft by hand and everything is smooth and solid
- Checked transfer case fluid
Any thoughts? Hints on what to troubleshoot further? I am at a loss and don't know how to proceed without spending big money to replace things like the entire rear end, etc. Many thanks for any help!