3rd Gen Poll: Rear End Noise howling when feathering throttle

It is possible that 75W85 is experiencing " sheer" which is when an oil loses its proper viscosity. We have no idea who the actual Toyota Supplier of oil is.

 

Just checked the R/O they used 75/140 on the replacement diff. Been quiet for 10K.

 

140 weight would certainly be thicker and drown a bit of noise down. I'd imagine you'd loose a bit of MPGs.

I bet they figured that prevent any wear or damage from such a heavy weight.

 

Never noticed any loss in MPG--just want to drive without a diff whine or a grinding groan.

 

They used 75/140 on my differential after replacement. It has been quiet for 2500 miles now. no loss of mpg.

 

Makes you wonder why they recommended 75W85 being so thin? The main logic being increased fuel economy? I think it does more harm that good.

 

Looks like they are going to replace it yet again. I only live 3 miles from the dealer so I may drive it straight home after replacement and swap to a heavier oil. That being said I use 75w85 in my 327k mile 4runner and it's fine but the oil seemed so much thecker than whatever almost clear fluid they put in the rear. It can't possibly be 75w85 if it is it's crap and I'll do some type of synthetic 140 weight. I doubt it will cause locker issues but it could...

This will be the second replacement diff. Corporate keeps saying it's normal and the highest up repair guy at the dealer (probably a Patsy for them) all the dude who drive modded trucks that work there say it's messed up. They even put it on the lift and used their listening device and said it was messed up. This one lasted 20 miles before making noise. So this will be the 3rd diff since the truck was built and I have 7400 miles. Glad I have a good dealership though. They seem to want to help. They said Toyota will not allow them to build one from parts which is what I've tried to push for. If this fails I'm gonna have to regear to 4.88 OME lift and 255s (33) is the final a, bit I don't want to spend the money. Or get a RAM diesel 6.7 which will have it's issues too but RAM and Cummins will fix it if it does and that's for 100k miles

 

It's MUCH more expensive--could that be the reason?

 

Probably but I'm thinking that would work. The reason I believe a regear will work is
1. People have done it and it worked
2. The regear uses a different t crush type pinion bearing to maintain better oreload, which is where I believe the issue is.

I would like to convince them to let me take the damaged rear chunk to a shop and I'll pay for it to be looked at them I'll bring it back.

 

Dealer told me they see this in Taco, Tundra and 4R--they use 75/140 on the fix.

 

Here is the part # for the oil off the R/O--00289-75140 Gear Oil
You can buy it on Amazon for $23 qt. or check this
https://www.toyotapartsdeal.com/oem/toyota~75w140~gear~oil~qua~00289-75140.html

Ask the dealer to use the heaver oil--no cost to you.

 

Think it would fix an already howling rear end?

At this point I’d try anything.

 

Because that will do you a lot of good when you are in derate on the side of the highway two or three times with a bad NOX sensor or DEF doser... New diesel stuff is brutal to try and get any longevity out of.

 

I cant even get my first one replaced. You're onto the third one wow....

 

They tried fixing my damaged rear with the new thick oil while we waited for the new diff [6 weeks]. It made it maybe 15% quieter, but did not eliminate it because the tech told me it was too damaged.

 

Hmmm I'll have to ask them to put heavy oil in it then I'll swap the front myself

 

I had a Nissan dealership do that to me with a Nissan Sentra that I had it was almost out of warranty they said the transmission was damaged and then they tried putting new fluid in and claiming that fix it. I knew better than that but I was just so frustrated with the whole ordeal I just decided to forget about it and move on..

" give us a call if it comes back".

 

So in your experience howl=damage?

 

The Master Tech stated he sees this in the 2gen at 120K--not 20 K. He was able to get the new diff approved, but corporate did not make it easy for him...They had him remove the transfer case and drive in 2wd with chassis ears before they agreed with his diagnosis....he used something like this:

 

Interesting.

I’m on my second diff already. About 5k on it and it has howled from mile one. First diff took almost 2k to start howling.

I might change the oil and see. Or have the dealer do it. I like my dealer so far.