Rear end concerns?

So I did search to see if there was anything similar but couldn't find anything specific enough to be of use to me. Sorry if this is another one of those threads that's been posted a million times.

So when I got my Tacoma there was a bit of a roar in the rear end. I assumed it to be a wheel bearing, I had a buddy of mine who was a Toyota tech for years drive it and he said it's probably a wheel bearing. And sure enough my pass side wheel bearing was shot, seal was leaking. So, I replaced it.

Unfortunately the roaring is still there. It sounds like a wheel bearing and speeds up with acceleration, but then when I let out of the throttle it goes away. I'm thinking pinion bearings in my diff? Or possibly a carrier bearing, but I'm doubtful that it's that.

Some other symptoms about it are the fact that it feels like I'm towing a boat anchor, and when i let out of the throttle it decelerates rather quickly, boat anchor again.

Am I on the right track or is there anything else I should be considering? 2007 trd off road with 136k

 

Dragging brakes are a consideration for this.

Are the drums properly adjusted? Ebrake fully releases?

 

I had considered that as well. I know the pass side is good as I just put a whole new axle assy in on that side yesterday. I have not pulled the driver side drum off yet. I will look into that asap.

Another thing I failed to mention is that the noise does not occur in reverse. However, I don't go very far or fast in reverse so I can't say that with 100% certainty.

 

Did a rear end drain and fill yesterday as well, old gear oil didn't look horrible, but I wasn't thrilled with what I saw. My guess is no it had never been done or if it had, only once and probably close to 100k ago. We put just under 3 quarts of 80w90 and a bottle of rear end conditioner. That, along with the new axle assy has made no difference.

 

What is rear end conditioner?

 

Its an additive we put in rear ends when we do any work on them. I am a mechanic for the city of Lexington KY, and I've been putting this stuff in every rear diff I have worked on for years now. I honestly don't know if it makes a single shred of difference, but I figured if it does it's worth a shot.

 

How do diagnose a bad diff on a city truck? Surely there are some light duty ones....... Tacoma would be the same procedure.

 

Typically we put it in the air and have some one listen underneath. Unfortunately, I cannot bring my truck into the shop as it would be a huge conflict of interest with it being a government shop. So I'm kind of having to go off driving it.

I was more hoping there were some common issues or something along those lines that might help me narrow it down.

 

Probably your gears. Letting off throttle/coasting changes mesh side (same as reverse). That’s the tell tale. I’d just live with it if there are no other issues. Some gears, especially aftermarket, are just noise from the get go. Yours might just be burned a bit from old gear lube

 

That was sorta my frame of thought too, although I didnt really think of it as something I could "just live with". I was worrying about it potentially chewing up my gears. I do plan to eventually go up in gear size though so if it's something I can address when that point comes that would be a relief