Grinding noise!!! HELP NEEDED!!!!

The noise is coming from under the truck and it isn't the rear end. When I let off the gas doing any speed over 45 there's almost like a gear grinding sound. As soon as I get back onto the gas the noise goes away. The tranny seems fine and doesn't shift weird. Anybody had the same issue or have any ideas on whats going on?? Thanks in advance

 

Check u-joints and carrier bearing.

 

U joints and carrier bearing are new

 

Were they replaced trying to solve this issue?

How / when did this begin? Same time as the lift by any chance?

How are you sure it isn’t the rear diff? Not argueing, just wanting to know.

 

Have the output shaft on tranny checked and the connection at the rearend.... also wheel bearings

 

Carrier bearing and u joints were replaced when I lifted the truck just because I wanted to make sure everything was solid. The noise started about a month ago. Lifted the truck about 2 years ago. Yes it is 4wd. I went through and rebuilt the whole rear end thinking that might of been where the noise was coming from. Transfer case oil I changed about a month ago and it looked brand new(no shavings or anything).

 

yes its 4wd and sound does not go away in 4wd

 

wheel bearings are new and that would be the shaft going into the transfer case correct? U joint at the rear end is tight

 

yes everything is up to par

 

Does downshifting the transmission to a lower gear change the noise, make it louder, quieter...??

 

once the truck gets under about 35 mph the noise goes away

 

So 4th or 5th at 50 mph the noise is no different than 6th?

 

was yours making the same noise as mine?

 

correct

 

I had the front diff issue. Also feels like a tire is out of balance or driving over rumble strips. Do you have that?

 

My issue is when its both in 4wd and 2wd so I don't think it would be the front diff

 

I skimmed over that. Yeah if it doesn’t go away in 4wd it’s not the TSB issue. Trans fluid been changed? Low? Torque converter? I got the code for the torque converter just before I traded in my 2010.

 

Since the u-joints and carrier bearing are almost 2 years old, you can’t assume they are good. If you haven’t already, I’d at least make sure all 4 bearing caps of each u-joint purge grease, check for any play, and unbolt the carrier bearing from the crossmember and spin it around the shaft listening for any roughness.

 

trans fluid has been changed and is full. Not sure about the torque converter

 

ive been back under there and checked and regreased everything. Carrier bearing doesn't feel any different since the day I put it on

 

I think if your transmission was going out you’d get a CEL. Mine went out at 59k, and every time I cleared a CEL a new one with a different code came on. Can you strap a camera with mic under the truck somewhere to narrow it down?

 

I strapped my gopro right under the transfer case and it was coming from right where it was mounted. Has anyone ever rebuilt there transfer cae?

 

Im trying to find a rebuild kit for it but am having no luck

 

Not much more I can do to help diagnose over the internet. Would be good candidate to diagnose with a ChassisEar, if you can find a shop in your area with one, or feel like spending the money.

Steelman 97202 Wireless ChassisEAR Diagnostic Device Kit

https://www.amazon.com/Steelman-97202-Wireless-ChassisEAR-Diagnostic/dp/B00123J79O

 

There's no rebuilt kit for them. In fact there's not much of anything Toyota will sell you for the transfer case. You could have a bad bearing inside it, which is something you can buy.

I think mine has a stretched chain inside it (can't buy it) so I bought a used one from a junkyard. It's been too cold to do (may even wait until next spring) but looking at it my plan is to remove the front driveshaft and the flange for it. Then I'm going to split the transfer case in place. The front half of the case is also the rear mount for the engine/ transmission so there shouldn't be an issue supporting the engine while doing it. The transfer case guts should come out with the rear half of the case. From there I would look for a bad bearing. I'm thinking this is going to be an all day job. If this is your daily driver then I would buy new bearings and seals and just change them. Also have gear oil and gasket sealer. It looks like parts of the exhaust will need to be removed and the rear driveshaft. The rear driveshaft will also have to be partly removed. That might mean removing the center carrier bearing.

Maybe you can do this with just jacks and brawn but I have a 2 post lift, tall jack stands, and a transmission jack. I don't think I would try it without at least a transmission jack and even then you'll need to make a way to hold the transfer case since the rear crossmember is in the way (which makes removing the transfer case whole much harder).

 

Thanks for the info. Just gonna have to tear her open and see what I find. What kind of noise is yours making with a loose chain?