Need help identifying drivetrain sound (video inside)

Been hearing this snapping sound coming from under my truck somewhere during acceleration. I have my suspicions, would love TWs thoughts. I took a video, link below. Happens only under load. The heavier the load the more noticeable. Worst is accelerating up hill, which is what I'm doing for most of the video. Seems to be intermittent. Sometimes it just won't do it, other times it will be super bad like in the video.

Video was taken out the rear slider with the slider into the camper shell closed so basically all that sound is coming up between the cab and the bed/shell.

https://youtu.be/npYxVImiJMA

Thanks

 

heat shield??

 

Your catalytic converter is f$#ked.

Take a mallet or hammer and whack on it while the truck is off. If you hear rattles coming from it, that's all she wrote.

 

I'd guess either heat shield, exhaust, or something stuck underneath. I'm assuming that you were just rolling on/off the gas and not depressing the clutch. Have you looked underneath the truck yet?

When my u-joints went they sounded more like chirping than this so I don't think that is the issue.

 

Heat shield is solid, I banged around on it and I can't replicate the noise.

Cat is solid, I banged on it with a mallet. I can rev to 4000 at a stop and it's dead silent. I can put on the e brake, rev it, and let the clutch out to stress up the drivetrain and it's still silent. But if I start moving forward there it is. Even lets up between shifts like you heard.

Yes in the video I started, shifted to second, then rolled off and on the gas a bunch of times without touching the clutch. It's loudest right when I got moving.

I went under there and banged and shook everything including exhaust and heat shields. Cannot replicate with mallet.

 

Let me think on this for a little bit. I'll get back to your thread in the AM. Interesting.

 

UPDATE:

I was messing around with it today. Going in and out of 4WD and goosing it up and down a long straight road. Two new developments:

Coincidentally, after going back to 2WD from 4WD, I heard chirping as well! But it gave way to the snapping shortly and only happened twice.

While in 4WD, I had trouble making the sound. I could hear it but it was maybe 10% of what it is in 2WD. As soon as going back to 2WD it would come back.

This both point to U joints in my opinion. in 4WD stress on the rear driveshaft is ~half what it normally is.

 

At least u-joints are easy to check. Jack up the rear end (or at least one wheel), put it in neutral, and then check for any play in the driveshaft.

 

U joints and or carrier bearing

replace em all.

 

If the u joints are suspect then start heavily investigating them. They go bad and emanate noises in a myriad of ways. Let us know what you find.

 

Update: U joint by the diff had one of the needle bearing sets turned into rusty dust. Not a single needle remained. It's nice and silent now.

207K on the truck.

Inspection on-truck showed no signs of U joint wear, it wasn't obvious until the shaft was unbolted and I could work the U joints by hand.

 

That's good that you found the source. When I replaced my u-joints they weren't as worn as yours. I guess that's why your truck sounded worse than mine!