I need help identifying this whine. its a constant whine weather im driving or coasting. it gets louder as you go faster. its not the axle bearing and there is no extra movement in the driveshaft. like you cant crawl under it and move the driveshaft up and down. I dont have a lot of cash right now so any help would be great. thanks. hares a link to the video. just listen over my exhaust and youll hear it

 

Could be the pinion bearing.

 

well wouldn't the driveshaft have some movement in it if it was a pinion bearing? and its been whineing for almost a year now so I figured if it was a pinion bearing surely it would have some play in the driveshaft by now

 

Actually, probably not going to have any driveshaft movement at all. Had an 01 sport trac that had a bad pinion bearing too, same kind of whine that you have, didn't think too much of it. Big mistake! 2-3 years later, boom! Driving down the road and the pinion slipped out and sheared all the teeth off and actually destroyed the inside of the differential. $1,200 and a new diff and axle later, and she ran like new. I would seriously look into it very soon. Don't make the same mistake I did!

 

Does the differential leak any fluid at all at the pinion or the axle seals? That is a clue that a bearing it bad.
It could be a bearing or the gears. I suspect gears from the sound of it. Maybe you got some water in the diff. Check the vent to see if it is still in place.

I had a bad front pinion bearing one time in a 1974 Ford Stationwagon which had a similar design diff. It sounded like roaring tires and the pinion seal was leaking as well as the right side axle seal.

 

I have no leaks anywhere. and I replaced the axle bearings already cause I thought that was it..but my vent tube is still there.. I changed the fluid again today.. added the friction modifier once again and still there is a whine

 

so, new information. I took my fill plug off my diff today and this is what was on it. a silvery gunk. any help?

 

Was the plug clean when you just changed the diff fluid?

If so, you probably have some chewed up gears. Could you see anything suspicious when you took the rear cover off?

 

yes it was pretty filthy when I changed it. and everything looked fine when I was in there.. the ring gear didn't look chewed up or chipped or anything. there was no excess play or anything that I noticed.. and I didn't see a lot of metal shavings...

 

That looks like bearing mud (just made that up), from a bearing being worn out. Could also be what has worn off the ring and pinion.

How many miles on that thing?
Do you carry heavy loads or tow?
Have you ever dunked the rear end into water, like mudding or boat launching? Running with water in the diff oil can take a serious toll on the bearings. Same thing as running it low on oil.

Looks like that might be worn out so you are getting the noise. If you do a complete bearing job and have the gears set up again you may be ok. If the R & P aren't chewed up you can probably re use them.

If you have a Trac-lock diff the gunk could be clutch material mixed with the oil

 

174,000 miles. no I never tow anything really and yes it does see some occasional mud at my hunting property.. but it didn't look dirty when I emptied the old oil out

 

Well, from the miles and the goo, like I said it might be time for a rebuild.

Throw a master rebuild kit in there and if it's LSD some new clutches and you will be good to go.

 

now im fairly mechanically inclined but ive never done anything more to a rear end rather than change the fluid and axle bearings.. how hard is it to do? I know about all the bearing preloads and backlash and I know the specs.

 

Patience is a must for the first time.

There are some special tools needed, Dial indicator and an inch pound torque wrench come to mind. A good breaker bar, one you can put a long cheater on to set the pre load and crush the crush sleeve. But it is doable, my son and I did his full size Bronco a few years back. I'm an old man carpenter and he was just a kid and we got it done!

Look for a good video specific to your diff and see if it is something you want to get into.
If you have an 8.8 it is the same theory as the 9.75, but they all are just a tad different.

You can start on this site and put in Differential rebuild or something similar in the search box and come up with a few hits, try different terms and see what you get. Plus there some smart guys on this site (I aint one of them) that can nurse you along if you have the time and patience. Also you can go on Jeg's website and I think they sell videos on how to set up the gears.

I don't know you or your ability, but I'd say don't be scared until you do the research.

Good luck and let us know what you decide.

Jim

 

well its $219 for the rebuild kit without the ring and pinion. plus the fluids..how much would it be if I had it done? approximately?