08-13-2019, 08:20 AM
Join Date: Sep 2015
Location: Lorton, VA
High-pitched squeal from the rear?
My í98 TJ (4.0L, 5-speed, Ford 8.8) has developed a high-pitched whine primarily on deceleration. I can occasionally hear it at a steady speed, but it is very faint. I cannot pin point where it is coming from even with the aid of 3 different people. KM2s don't don't help too much here. The pitch is very high (and pretty loud) but is right on the edge of hearing range so it is hard to identify. Iím pretty sure it is coming from the rear-end but havenít ruled out the transfer case. Turning left or right has no impact. It does not do it when the Jeep drive-train is cold. After a short run down the interstate, it becomes present. It is mainly from 35mph down to 0mph just before you stop. When you apply the brakes as you are stopping, sometimes the noise will dissipate slightly Ė Iím thinking something is unloading.
What Iíve done (and has made no change):
1. Replaced my known worn (CY pin was galled) rear DS with an Adamís.
2. Changed rear diff fluid (that still looked good and didnít smell bad, extremely small amount of glitter present Ė Iíd call it normal).
3. Change TC fluid (old fluid looked OK Ė still had some pink to it but dark).
4. Replaced a passenger rear brake caliper that was suspect as sticking (the dust seal was torn and loose).
5. Front and rear pads are both acceptable thickness (this is not seemingly a brake squeal).
6. Removed front drive shaft Ė the noise does not go away.
7. Removed rear drive shaft and the noise is less prone.
Iím thinking that acceleration pressure from driving is what makes the failing item develop heat and cause the noise. From the reading Iíve done online, it would imply the pinion bearing has lost its pre-load? This is probably starting to hurt the bearings, but i'm still just guessing. I have not put a socket to the nut, but I didnít feel anything wrong when replacing the DS. I guess thatís my next check. Of all the axle bearings Iíve replaced, they have always growled, and you could make them come and go by turning left and right. I havenít ruled out the bearings in the TC or SYE. I would assume they growl also.
Please help me out here as this sound and it's chase is making me crazy!
'98 Chili Pepper & Spice 4.0L - AX-15 - 4.56 D30/Ford 8.8 - 4" SL on 33s