Loud howling noise in rearend

I have very loud howling/whining noise from rearend. but it is only when under load. With foot off accelerator there is not noise at all, but under any load it makes a fairly loud humming/wining noice. Doesn't seem to make any difference if I swerve one way or another and transfer the weight from side to side. Also makes noise in four wheel, didn't really use it just checked to see if noise would improve.
Put truck on the lift. With husband pushing pressure on the driveshaft, it seemed to quiet and almost completely stop. So we changed carrier bearing, no help at all!
PLEASE help. I really want to know any suggestions bef ore I have to buy driveshaft or rearend!

 

Wheel bearing?

 

Uh sounds like the rear diff

 

Drain and change gear lube. If you got lots of big metal shavings, then it's a good chance the diffy is bad.

 

Doesn't sound like when my diff went bad. Mine made noise on deceleration and when I put it on a lift and put the truck in drive at idle (professionally done on closed course, do not try at home) I could hear it clunking.

Can you explain more about how pressure was placed on the shaft to make the sound go away? Was the truck in drive? How was pressure applied?

 

That's what she said

 

I'll admit, the Beavis and Butthead in my mind woke up when reading the subject line. I could hear Beavis giggling.

 

All this. My experience has been the same with a diff going bad.

Also you should not be turning on a dry street in four-wheel-drive. But you should be exercising the 4 x 4 monthly.

Next cheapest step is grease the Ujoints if they have the fittings for it, or replace. Even if that’s not the problem, at least you know you can rule it out.

 

If you can make the noise appear and disappear by feathering the throttle it's most likely a pinion bearing.

 

WOW!!! I was just saying the noise I’m hearing I can feather the throttle and make the noise come and go.

 

Check the fluid level in the rear diff. It's easy to do. Just remove the fill bolt on the back cover and you should be able to put your finger into the hole and touch the oil. If not then try to find something clean, like a piece of electrical wire that you can put one end into the hole and see how far down the oil is from being full. Usually bearings inside it don't go bad unless your oil leaked out. If it is low then add some cheap gear oil to fill it up and see if the noise changes. Until you are sure that the diff isn't the issue I wouldn't spend much money on good oil that you could be draining right back out again. If adding oil makes the noise change then you know what the problem is.

 

I changed the Rear diff oil and the noise stayed the same. I do admit that the old oil was thick and creamy. The level of the oil was good before changing. I just though it was weird that the sound I’m hearing that I could make the sound go away by feathering the throttle. It’s not a loud noise but kind a like sandpaper rubbing back-and-forth.

 

When you say creamy are you talking the color? White or pale green colored oil usually indicates water has mixed in with the oil.

 

It’s was very light brown and the last of the oil had foam that had came out. I used a paint strainer to see if there where any Metal shavings and only found one very small piece. My friend that has a Tacoma we where doing the oil diff change the same time said wow, That diff oil has never been changed. I picked the truck up used @ 50,000 and I’m @ 100,000 when I changed the diff oil.