Front diff or transfer case?

[ls1frc]

Hey guys, having a front diff issue I think.

When I am in Auto, I can hear a whine under light acceleration. Definitely sounds exactly like differential whine. I am not sure how Auto mode works, so I wasn't sure if it was for sure the front diff or possibly the transfer case. Is Auto mode slightly engaged with clutches or something? Not sure why it would whine unless it enabled all 4 wheels.

I got on it hard yesterday in Auto and as the power really picked up around 55 mph, I could actually feel the front end dragging like it had resistance.

Not sure if it matters, but I had the incorrect fluid in my transfer case for like 3 years. I had AutoTrak in there when it was supposed to take D6 trans fluid. Per BITOG forum, this shouldn't have hurt it.

There's 152k miles on the Truck

 

[Bill 1960]

If it sounds like a hypoid gear whine I expect it is. The front gears are spinning all the time in auto. Plus of course the front driveshaft and front drive parts in the transfer case, so any of that CAN make noise.

I would change the gear oil and try a heavier weight, just to see if the noise changes. Not as a permanent thing, just a diagnostic aid.

I have had some degree of extra noise in 4x4 with every part time 4x4 I’ve owned.

 

[ls1frc]

Yeah I tried the gear change to redline synthetic, didn't help. I'll likely just run it the way it is then and not worry about it. I only need 4x4 in bad weather conditions anyway.

 

[Geotrash]

I had a similar issue in my old ‘02 suburban. Went on like that for a long time until it started making a lot of noise with 4wd engaged. Had the front diff rebuilt for $1200, if I recall correctly. The guy I sold it to is still driving it 4 years and 80k more miles later.


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