Loud Noise - only when accelerating, 45 MPH and above.

Sounds a little like the Millennium Falcon (only way I know how to describe it)

Only starts when I get above a certain speed, and lightly pushing on gas to accelerate. If I press harder to go faster it quiets down.

Also happens when I'm releasing the gas. It is coming from the rear, underneath.

Here is a link to a video. I'm alternating between pressing and releasing the gas pedal

https://photos.google.com/share/AF1...?key=OElxeXFrZG1lSVpuME9GRHdyNHVYM001TDdfVU13

 

Kind of sounds like a train horn from far away, that's odd. I had a sort of similar noise but more chirpy...it was in sync with the engine RPM speed. Turned out to be the bearing in the AC idler pulley was bad and needed replaced, pretty easy/cheap job. This sounds different but that's one thing to check just to see. The bearing in mine was very loose, you could get under the engine and move the pulley back/forth with your fingers

 

Edited to add: It's coming from the rear underneath.

 

sounds like a bearing whine. check carrier bearing if 4x4.

 

That sounds like something I'd want to find before I keep driving the truck! How long has your TPMS light been on? Possible tire problem or alignment issue?

 

Its a 2 wheel drive.

I agree, that sound is scaring the crap out of me.

The TPMS light came on a week or so ago, checked air pressure, added air to the tire, it went off. Came back on this week. Taking it the tire store this weekend to get that checked.

Dont think its related to the tire, sound is directly related to hitting the acceleration pedal.

 

Sound can be tricky. Maybe it's not coming from the rear. I'd start checking pullies then wheel bearings.

 

That's what I was thinking. Sound can be real hard to pinpoint sometimes.

 

How many miles? Sounds like rear differential gear whine. Start by draining the oil and inspecting the contents for metal shavings. Replace with a heavy weight oil like 85W-140, see if that helps.

 

You say rear.... First thing I'd look at are your U- joints, especially since the noise is prevalent under load.

 

Drive line noise, especially upon de-acceleration is generally in the rear end. Check the rear diff fluid immediately. Disconnect the driveshaft and inspect the u-joints. With the shaft out, grab a hold of the pinion and check for excessive play. You may want inspect the third member for abnormal wear on the ring and pinion gears.

 

Sounds expensive like the differential is dry as a bone.

 

Does it always happen at the same RPM?

 

Unfortunately, this is the issue. Appreciate everyone's assistance and responses.

 

You opened the drain plug and little if anything came out?

 

I took it to a shop, but yes it was empty. Also, could see where it was leaking out.

 

Ouch.

 

Didn't notice the leak?
Glad you got it solved.

 

At least you caught it before the diff seized up on you on the highway or something, that could have been bad

 

Ugh.. Overhaul vs Replacing the Axle assembly? $$$