Ive been reading about rear end whines coming from the diff.

Doesnt the diff fluid that is in there lube the bearing for the pinion.

I am just a little lost. I had a diff leak in the pinion seal,,it was there when i

got the truck. I didnt really think that it all leaked out,, so i drove my truck.

For almost a month i drove it. Then one day i was going to work and my truck

acted like it was draggin an achor. Realized it was the amount of fluid in my

diff. I put fluid in it and got the seal fixed. I did have a roar from rear end of

truck.

So if you have enough fluid in diff the bearing can still go??????

Can someone please explain.

thanks

 

This image is for 8.8 ring gear.... may not apply, but in principle....

The lubing of the pinion is dependent on level of fluid. The head/ crown is in a bath at idle, as it has some contact. Otherwise the lube is in motion and slung. Don't forget those axle bearings too; they are centerlined and once the fluid drops below this they no longer are fed.

Note the oil slinger in pic.

 

If the diff. was low and continued in operation, it is very likely that damage to the pinion and ring gear occured. That damage commonly called crows footing occurs when the surface hardness of the teeth is compromised (lack of sufficient lubrication). If you removed the rear cover and examined the concave and convex side of the ring gear & pinion; you would more than like see a somewhat blackened tooth contact surface with hashy looking raised on the tooth surfaces. Even if you replaced a burned or spalled inner or outer bearing (with a gearset that was damaged by insuffiicient or improper lube); the irritating noise will remain from a cooked or damaged gearset. One of the most important things that people overlook when servicing the differential is installiation of improper lube. In hypoid drive axles, always use gear lube that contains GL-5 additive. Failure to do so will result in premature wear of the ring and pinion set and lead to noise and future pproblems from the drive axle assembly.