Originally Posted by CobraCommander
So last week I had an Idependent shop slap on some new rotors for me I was struggling to pull off, anyway they reported back to me that I had a leaky pinion shaft leak, so I had them fix it. Fast forward 500 miles later and on my way into work today I hear a hum from the back end (rear differential?) kind of like if I had put on some real Knobby tires. This hum happens while acclerating and decclerating and pitch varies with speed of car.
Could the seal they fixed failed causing fluid to leak out and now things are heating up? BTW I have the V6 sport FWIW.
Any thoughts, I brought it back to them to look at so I want to sound somewhat informed when I call back for a check up prior to having them do anything other then looking at there previous handy work.
I suspect the shop may have not understood the correct proceedure regarding re-assembly and setting the pinion bearing pre-load.
This may have been their fault, by overtorqueing or it may be a coincidence.
A pinion bearing can fail anytime.
Sometimes, a seal failure is a precurser to a bearing failure too.
The pinion develops a fractional wobble due to the bearings which are at the very earliest stages of failure.
The wobble, tears the seal lips and pinion seal leakage is the result.
So......although you want to point a finger, it may not be justified.
Now, if you told me the rear end was howling within 50 miles of the repair, I'd be more inclined to blame the shop for poor re-assembly.
Regardless, your description is that of pinion bearings that have failed and need to be replaced.