Okay so I am experiencing some noise in the drivetrain. Furthermore, it sounds like it is coming from the rear differential. It is a constant sound as long as the truck is moving. Kinda sounds like the sound that comes from off road tires. Anyone ever have the same issue or know what it possible might be? I'm going to service the oil and see if that does any difference.

 

When mine did that noise the pinion bearing crapped out.

 

A whine? A whine is usually the ring and pinion dying. A clicking or grinding is usually a bearing going bad, or being run dry.

Pull the fill plug immediately, stick your finger in and feel for gear oil. If you don't feel anything, get some 85-90 from your local store in there like yesterday.

 

Is it like a humming sound?

 

either way bearings or ring and pinion that 3rd is gonna have to come out... gl

 

is your u joint bad? lol I destroyed mine during winter and fixed it in spring time

 

Yes it is a whining sound. Oil is full but I think I should change it anyways. Am I better off replacing a different rear diff or any other options?

 

If it's whining, the damage is done and changing oil won't put metal back on the bearings.

 

You could just consider it a "feature", my old Lotus Eclat had a whining diferential - when I found a rebuilt unit cost $1000, I purchased an oil addative and put that in with new oil - it made it a little quieter and kept an eye out for someone parting out another.
I think the addative was made by "millers" or someone (I dont think it was beer).

 

Would it be a waste of time and money to service the oil when I can put the money into another rear diff?

 

Well u shouldnt need the entire diff, just the 3rd member.

If the fluid level is low then maybe adding some oil might help.

Easy way to Check if the pinion bearing is done is to move the driveshaft right at the pinion. If u have lots of movement then ur culpit will be there. Otherwise it aint too hard to pull the 3rd member to inspect it

 

sounds like what i just did to a chevy at work. whining fromt he diff on accel and decel, i changed out the bearings and hte noise was still there, after pulling off the cover again ( its a chevy ours dont have a cover, you pull the 3rd member out ) i found a nasty wear pattern on the ring gear, replaced the ring and pinion and the noise was gone. you can get a rebuilt 3rd member for like 500 bucks or go to a junkyard and pull one and inspect it before you buy it. either way dont bother wasting money on changing the fluid, the diff is done, save up and replace the diff and the oil at the same time.

 

talk to mightymouse if you need somethin'

 

If you have to change the 3rd member, you should look into a toyota electronic locking 3rd member that came factory in the 4runners and tacos (pre runners and 4x4). You're in cali so it shouldnt be hard to find one (i've been looking for one for about 2 plus years now). Here is a link with a wealth of knowledge: Erik's Toyota Differential info

 

$500?!? I can get a used rear diff off a buddy for a fourth of that price.