Rear differential humming noise

hey fellas I know this is another old topic but need some ideas, 2020 sr5 Tacoma got not long ago a noise coming from the rear, checked the tires (old but no cupped), checked the rear bearings but I am almost 100% sure they are good (tested them all 4 thru different ways), last when spinning by hand the rear tires heard a noise from differential not too loud but of course at low speed. I been reading some about it but nothing conclusive, some say it is normal, but I don't really like it. I have the 7 years or 100k miles power train (currently has 37k) that being said I hate dealerships worse than going to the dentist lol. I am concern about taking it in and they will say it's normal or something else to avoid fixing it and will end up paying for stupid diagnostics with a dead end.
anyone out there ever had experienced same or have any advice on what to do?
note: I wish the car care nut shop was nearby to have a proper diagnosis.

Thanks in advance

 

Hard to tell where from rear diff. You the original owner? I would try draining rear diff oil, and see what is condition of gear oil. But make sure can remove fill plug first.

 

ya original owner, agreed on always removing fill up plug 1st, my only concern is that might void the warranty, dealerships find any excuses to void it

 

As long you use GL-5 gear oil with receipt you probraly safe. But if worried about warranty, you have no choice. Take your SR5 to dealer to check noise out.

 

ya I am starting to process that idea, God knows I hate going to that place!!

 

Some dealers give more damn than others so if you have a couple choices, try one then move on to the next if you're not getting anywhere. You might as well try the warranty route; that's what you paid for.

 

you are correct, the only thing is if they start saying it is normal when it is not and then I'd be going in circles. Honestly, I am not sure if the 7years or 100k miles power train warranty applies only for that dealership or any other.

 

Could you elaborate as to just what the noise is and when it happens? While on the road not in your shop.

The most "normal" sound is a slight hum with just minor acceleration or deceleration - feathering of the accelerator. I have it, many have it; I can't hear mine anymore with MT tires.

 

ya of course, humming noise starts around 40 plus mph, and gets louder as the speed increases, not sure how to describe it, like a cupped tire or bad bearing (not those things) but definitely not howling or whistling. by hand differential doesn't grind but heard a weird noise.

 

What happens to the noise when you feather the accelerator? Slightly on, slightly off the accelerator - not hard acceleration.

 

I'd say it is constant matching the speed, never tried setting A/T on neutral

 

I'm not talking about speed, but torque applied to the drivetrain.

 

didnt pay attention to the it TBH

 

Hi there, noise is barely changing the pitch despite the torque

 

OK, it’s not likely to be what many of us have from the factory. Take it to a transmission shop, have them drive it and they will give you an opinion.

 

Understand the hesitancy of inflicting the dealer's wrath upon yourself. Still might want to take a dip into the pond and see just what a transmission/gear shop says. Incremental prep for something you don't really want to do.

 

Got an update according to the dealership the driver side wheel bearing is bad and it's included in the powertrain warranty, I won't argue because it is covered but I have my doubts, we will see after the repair it that fixed the issue

 

Honestly, with what you have mentioned above as to what you're hearing, this very well could be an accurate diagnosis. Definitely roll with that at this point. The last thing you want to do is mess with the differential if you dont have to. Would be shocked the amount of technicians these days that dont have a clue on how to properly put a differential back together and reinstall it. Brought my previous truck back to the shop 4 times for that reason.

 

ya I will stick to it and see what happens, but got the feeling is something else, 37k miles, never carrying heavy stuffs, temperature on the hub within normal range, no play or roughness when spinning, too many things against that diagnostic but let's wait, thanks for exchanging ideas/opinions