front differential whine

[internic]

ok guys I just redid my front driveshaft u-joints. it still makes a horrible whining noise when in auto 4, becomes noticeable around 30mph, only noticeable when accelerating or decelerating. Yes I have changed the fluid before but i had a friend pick up the gear oil for me and he bought super tech brand from wal-mart lol. so i was wondering how many of you have the whine (i know alot of you have it, just to varying degrees), and also i would like to know what brand/weight you guys put in the front diff. i think the manual calls for 80w90?

[cliff-o2-z71]

I recently changed my front diff oil at 50k. I was suprised at the metal stuck to the magnet on the drain plug. I don't have any noticeable noise there. I went back with Valveline Syn. 90w. I wonder why the rear drain plug does not have a magnet? Cliff

[mjgjr72]

Originally Posted by internic

ok guys I just redid my front driveshaft u-joints. it still makes a horrible whining noise when in auto 4, becomes noticeable around 30mph, only noticeable when accelerating or decelerating. Yes I have changed the fluid before but i had a friend pick up the gear oil for me and he bought super tech brand from wal-mart lol. so i was wondering how many of you have the whine (i know alot of you have it, just to varying degrees), and also i would like to know what brand/weight you guys put in the front diff. i think the manual calls for 80w90?

hate to say it but it is probably the pinion bearings

[mjgjr72]

Originally Posted by cliff-o2-z71

I recently changed my front diff oil at 50k. I was suprised at the metal stuck to the magnet on the drain plug. I don't have any noticeable noise there. I went back with Valveline Syn. 90w. I wonder why the rear drain plug does not have a magnet? Cliff

the rear diff usually has a magnet on the cover

[cliff-o2-z71]

Thanks, it sure would be easier to check and clean it if it was on the drain plug. Cliff

[mjgjr72]

Originally Posted by cliff-o2-z71

Thanks, it sure would be easier to check and clean it if it was on the drain plug. Cliff

all you should see on the magnet is fine medal particles, this is normal wear, any larger chunks and you have a problem, it is always a good idea to inspect the rear when servicing , it's pretty easy to take the cover off and check the gears to see if they are wearing good and look for any chipping on the edges of the gear teeth

[internic]

alright for you pros...

if my pinion bearing was bad, what would be the signs? let me phrase it differently. it whines on accel and decel only. also, when i had the front driveshaft off, the front pinion shaft would spin freely but make a slight noise every half revolution. since the front axle wasnt engaged, im assuming this could be a bearing problem?

[mjgjr72]

disconnect fornt proppeler shaft and try pulling in and out on yoke and wiggle side to side you should feel no play, or put on lift in 4 wd run in air and use stethosope to listen to front diff case to locate noise

[NoRiceHere01]

the pinion bearing sounds right. i had the pinion seal replaced on my mustang (i know, i know. sorry im back to chevy now so its ok) and when the idiot put it back together he didnt set the pinion depth right so it was too tight and ruined the bearing and the gears. had a whine on accel and decel. got struck by someone who ran a red light before i could fix it. my point here is just so that if and when u fix it u should check the gears themselves too. Richmond's got em for around $180 i believe.

[Silverado Brethern]

IMO...It is normal for the front differential to whine, especially when going 30mph. I highly doubt it would be worth to even try to fix this problem, it causes no harm (if all it does it whine), and most likely it will re-occur even if you do try to fix it. Unless something else starts acting weird or making noises dont worry about it, hense, if it isnt broke dont fix it.