Rattle sound...Time to figure it out!

Ok, so this has been around for about 4 months, but not it is finally getting on my nerves.

There's a rattling sound coming from under the truck in the front of the bed or rear of the cab. Here is what I found from observation:

-Kicks in at around 25mph right around when I shift into 3rd
-When I shift into 3rd, it really becomes clear, and can be heard in 4th and 5th just as loud.
-It only rattles when my foot is on the gas pedal; goes away when I just coast in gear or engine brake.
-Revving in neutral does not produce the rattle.
-I have removed the heat shield above the catalytic converter already, so that is not the problem.


Any ideas or suggestions? I can't exactly crawl under the truck and look for it because it kicks in at about 25 mph and I would rather not be under the truck at that point. It also doesn't show up by revving so I can't have somebody do that. It's really driving me crazy though.

 

check your carrier bearing or along the drive line. Bc it seems to only happen when in gear and driving. That would be my first guess...
I would maybe wiggle it to see if you can hear it or if you have alot of slack in your CB.

 

Hmm, but then wouldn't it make the noise all the time when it's in gear and not just when I press the gas?
The drivetrain is still moving when my foot isn't on the gas but the truck is in gear.

 

Not necisarely, bc when you give it gas in gear its putting strain/lowed on the drive line. Even though its still moving/spinning when you let off the gas, theres no power going to it, or lowed. Just from your description it sounds like possibly the drive line. But It could or could not be it, its just somewhere to start man....

 

i havd the same problem. but mine squeks when i let off. and mine is an automatic

 

Alright. It also could be the cat hitting the crossmember, I'll check both when I get a chance.

 

Mine has been doing the same for about 6 months, I just learned to live with it. It happens to me just by revving the engine. I crawled under there and just played with it a bit, wiggling it around and the noise stopped for a while.
Keep us posted on the results.

 

I had a similar noise and it was a small bolt that had loosened up on the door where it closes down low