2008 H3 68000 miles 3.7L engine. Recently, I noticed a humming noise coming from the rear so I had the differential serviced. For a few days I heard nothing. Then going down the highway I heard what sounded like my drive shaft was dragging the ground. Luckily, a repair shop was nearby so I had it looked at. Naturally, they think I need my rear diff completely rebuilt at a cost of about $1500. I asked how could it be bad when it has so few miles but they were like that doesn't matter when it's bad it's bad. Personally, I don't think it's bad and the worst thing my H3 goes through is heavy highway miles.I have heard about it possibly being a broken bolt or a loose pinion nut. Has anybody gone through this? It sounds like you can hear each gear tooth by tooth as they engage winding up and slowing down as the vehicle accelerates or slows down. Help!

 

the dif s hard to work on but ez to peek into. just pop off the cover and look around,wiggle the ring gear--see what gives. that's a start. no charge!

 

as you drain the fluid out of the diff before opening it to take a peek, strain it through some cheesecloth or a thin rag to see if any parts get strained out. Remember, the fluid stinks like a pig farm in July so wear rubber gloves and don't get any on ya. Off with the cover and see if any teeth are sheared or have wear marks causing noise.

 

Check your in service date. If it was a late 2008 and not put into service until later, you may have some 5 yr. 100K powertrain warranty left.

 

I've never had a rear diff go out in anything at 68K miles, but I know other people who have. When they start whining, it is because the pinion shim is worn and the gear teeth are not completely engaged. It slowly gets worse over time. That creates metal particles in the diff.... in the diff fluid ...that finds its way in all bearings and eventually leads to failure... or so much racket that you have it looked at and they tell you it is in need of a rebuild. You can pay them then, or pay them later when it toasts completely.

When you say you had the diff serviced, what exactly was done? I'd be looking at that real hard.

Was it filled properly, with the correct lube, and drain plug properly in place?

 

My rear diff went out on my H3T at about 50K, ring & pinion needed replacement. Lots of whining going on, it CAN happen.

My front diff has also been rebuilt (at 43K), and my transmission (at 36K), and I've had to swap in a new tcase (at 60K) already, so be aware that if you use it as intended, parts will wear out!