Humming noise coming from the rear area

Need some advice my fellow members, My 2005 prerunner trd has a humming noise from the rear area that comes and goes at random. The truck has 260+K miles and the rear bearings have never been replaced. I replaced the differential fluid 10yrs ago and bout 125k miles ago. The shaft carrier bearing has never been replaced either. I replaced the U-joints 10 yrs ago and they look good. I have been hauling on the back of the truck bed a 350 pound engine from another car for the last 6 months that needs to be dispose off( wonder if that matters) .

Anyone have past experience on this ?

 

Humming could be lots of things and it's always hard to diagnose on the internet but if it were my truck, I'd change and inspect the rear diff fluid next. At that mileage between changes, you're due for new fluid anyway and doing a change will allow you to look for forbidden glitter in the fluid.

 

hey thanks for the reply desertratliff. i'm definitely gonna replace the fluid tomorrow morning. Do you think the 350 pound weight in the truck bed makes a difference on that differential going bad? i also ordered the carrier bearing just need the time to replace it. oh also forget to mention that the rear differential does get a little warm after a local drive of 15-25 miles.

 

First Id make sure there isnt some old guy sitting back there huming....

I would start with the diff fluid and see if there are any metal shavings in there. When mine went it started as a low hum and went to a metal on metal whine. And remove the engine, that way you can isolate without 350lb variables

 

I can only speculate, honestly. Diff, carrier bearing, rear wheel bearings or even one of those relatively new u-joints could factor in to rear humming but I don't think a few hundred extra pounds are going to push anything to the breaking point. Lots of us running heavy without issues. That said, 140k miles is a lot to ask of diff fluid under heavy use so that's where I'd start.

 

Hey thanks for replies guys. I did replace the fluid yesterday and it made a little difference (oil was dark but little metal shavings). I noticed the driveshaft is not perfectly strait it bends down a little at the carrier bearing So that's my next thing to replace ill be doing it some time next week. I was thinking maybe the tranny rubber mounts could be weak. i'll keep y'all posted

btw i told y'all wrong, the truck has 279k miles

 

UPDATE; I replaced the carrier bearing 2 days ago and it seems to drive better now but you can still hear a slight humming noise coming from the rear area at random times especially when going up hill or down hill. I really don't want to get into the rear bearings at this time so i'll drive it like that for a while and see , time will tell. I have never done rear bearings on a truck before, any good youtube videos out there guys??

 

I like this one gets right to the point without any useless chatter

Toyota Tacoma rear wheel bearing replacement - YouTube

 

okay thanks, i'll look into that and see if it's doable by a mediocre DIYr like me