My 08 2wd V6 4Runner with 47k miles has a rear diff "whine". I took it to my local dealer. They drove it, checked the fluid level and did what they called a diagnostic check. The diff whine is obvious in that you can release the gas and the noise fades away and comes back again and increases in pitch as the gas is applied again. In the end my dealer told me he couldn't repair it under warranty with these points to note:
1) dealer says it has a "slight" abnormal noise in the rear diff but his technicians can't say for 100% sure where it's coming from - pinion bearing, carrier bearing, ring gear to pinion gear setting, etc. (my wife even complains about it it's so obvious and she's far from "mechanical").
2) because they can't fiqure out for sure where it's coming from, if he warranty's it, he admitted he's afraid Toyota will "call" for the repaired parts. If, after thet fact, Toyota "tests" the replaced parts and rules that it wasn't bad enough to repair under warranty, they will then make the dealer refund the cost of the repair back to Toyota. And, the service manager flat out told me, he has to answer to the dealership owner's and it's "all about the bottom line"...(very unlikely Toyota will actually honor the claim, me be out the door with a repair then Toyota will put these parts through a test to find they don't agree they should have been replaced under warranty).
3) the service manager assured me if anything needs attention, it will surely get worse and even if it this happened after the 60k mile warranty is out, Toyota is good about fixing them anyway! (amazing given the noise is very evident now yet the dealer says he can't justify the repair to Toyota now when the car is under warranty).

My position to the dealer is this - no amount of whine from a rear differential is normal or acceptable. Although I'm sure it's not common with a Toyota, it does exist in my Toyota, it is a quality issue that shouldn't never rolled off the assembly line that way and Toyota (not the dealership) should make it 100% correct under warranty. Period. If I had wanted Dodge quality, I would have purchased a Dodge you know? It's not my concern as the customer that his technicians can't specifically locate exactly what is causing the whine in the diff. If that's the case, Toyota should replace the entire axle assembly (diff and all) and the problem is surely solved - it just makes good sense. But, without question, I should have a quiet rear diff regardless of how the dealer has to "justify" the warranty repair to Toyota.

I'm no idiot and I'm frustrated and don't know how to proceed. I have a good understanding of cars having wrenched on them for years and being a mechanical engineer by day. What should I do? Who should I contact to get this resolved? Thanks for any opinions, comments, etc.

Interesting. Is this possibly the harmonic Drone a lot of us talk about?

I notice a drone sound/vibration on occasion when I'm in 4wd (all winter) and around 60-80km/hr and it disappears when I release the gas.

Here is what I would suggest you do:

Get the dealer to give you in writing that they will extend the 60K warranty on the diff.

I would also immediately get in touch with Toyota America and pitch a royal fit. You actually have little to nothing to lose here.

Keep us posted, maybe we can help you to pitch that fit.

The dealer isn't going to give me any extended warranty in writing on the diff. Heck, like I said, he says Toyota is real good about doing warranty repairs after the warranty runs out. What a joke when they won't simply fix it now which is what should be done. I asked him for a name/number for a regional service manager and he says there really isn't one. He simply gave the the 800 # to Toyota customer service. This is a complete joke. I have already wasted 2 hours of my time on this with no luck. I'm going to call Toyota but I'm not sure calling the generic customer service line is going to be of any help. I also have 2 other dealers fairly close (50 miles or less). Should I go to them and go through the same thing I did with my closest dealer? This is very aggrevating. These gear type problems don't go away and I can just see that it will get worse and worse then I'll have to have it fixed on my own dime after the 60k warranty is out!

Your dealer is lying. Mine complete rear diff was replaced for the exact same issue at 20k. Start complaining to Toyota in California. The rear diff program replaces the entire rear diff in one piece...no rebuilding. I would respectfully complain and call the other dealer service managers. A rear diff replacement is at least $2k. Oh BTW, the Toyota regional rep drove mine and approved the repair...also they gave me a loaner while they repaired it. The new diff has some harmonic at 40 mph and a decel whine at 55-45 but not the 70mph tip in throttle drone like it had. I'll change the oil at 55k and send it to blackstone labs for analysis to see what if any wear metals are in it.

Almost forgot...I took mine in when my 12 year old daughter asked what the whiney noise was......

KB084Runner, you mention "rear diff program" in your reply above. Is this some sort of common knowledge that these diffs had issues and there's some recall of sorts I should be involved in?

Can you describe this noise, when does it happen?

Got another dealer in town?

Whether it's gears or bearings, they could write it off as gears and say they replaced the bearings while rebuilding the diff. Could they not?

It's more noticeable above about 50mph. If, for example you are running steady at 60 it's very noticeable. When you let off the gas it gets quieter then comes right back as you apply the throttle againl. Also, it is more evident pulling up a grade then say when you are descending one. But it whines and is evident at any speed. It's just much more evident at highway cruising speeds.

My local dealer just plain wasn't interested in helping me. Like I said the service manager told me without hesitation, it's about the "bottom dollar" and he was afraid Toyota would somehow make the dealer pay back the claim amount since his tech couldn't pinpoint exactly where it was coming from in the rear axle. Bottom line is that he wasn't interested.

I called the 800 number to the corporate headquarters customer experience center. The gentlemen was very nice and listened to my dealer experience. I made it very clear I wasn't calling to complain about that experience but wanted to focus on getting my rear diff repaired as it should be under warranty. After about 30 minutes on the phone, he asked me if I minded taking it to another dealer to which I agreed. He said if I had a similar experience and it wasn't repaired, he would turn my case over to a case manager. I was assigned a case number and got this person's name that I talked to. I asked him if they had any "recalls" or "service programs" concerning these rear diffs and he said none showed up. He said he understood my frustration with the dealer comments I had to listen to (posted up top) and said to call him back as soon as I had another dealer look into it. I'll make an appt. as soon as I can with another dealer and see what happens. This is very disappointing but I'm going to remain positive and scratch the 1st dealer visit up to a crummy dealer. Maybe the next dealer will get the ball rolling with warranty to fix my rear diff and this will all go away.

Mine did the same thing. Water got into the front pinion bearing. Had to tear the whole diff down, took 4 days to get the part and get it fixed. Cost me a cool 800, but I was at 130K, only "major" repair so far. Good luck man.

That service manager was blowing smoke. I was a tech for a different company. Probably overhauled a few hundred rear ends in my day. If the failure is coded to the ring and pinion it covers the bearings, seals, spacers and gear oil. It is a justifiable repair. I guarantee Toyota no longer cares about advancing the design on a that year model's rear end. They will never call for a ring and pinion. They are heavy and it will cost them too much in shipping costs. On the off chance that 1 in 50 didnt need to be replaced. The cost vs recovery is in the favor of the dealer. They may call for some other part of the repair like a bearing or seal, but thats just to validate the repair. I under stand all makes are squeezing the warranty repairs to cut cost and post profits. That service manager doesn't have a clue. It really sounds like they didn't want to fix your rear-end. Its a really crappy situation. Dealers put them selves out of business bottom line, but thats another rant.

That was the term my delaer used and they told me that Toyota no longer has the diffs rebuilt locally but swap out the entire assembly for a new (probably refurbished) one from the factory. I know exactly the noise it is a off pitch whine on the freeway when you just have the throttle slightly engaged and it is under light accelerator load. It then disappears when you back off the throttle. If that is what yours does then it is the pinion bearing.

At my first complaint the tech said he didn't hear anything... Then when I went back they put a microphone on it and came back and said..."Yeah we hear it". Once that happened they got the Toyota rep to drive it (2 weeks later) and he approved a new diff. But the new diff is still noisy just not as noisy. I think the issue is the factory pre-load setting on the pinion gear. They probably just set them all at one spec versus shim and adjust for each axle set like in the old days when diffs were set up by master mechanics and lasted for 500,000 miles

But bottom line: don't give up until you get a new diff because it will never stop whining and they owe you the repair.