06 f150 fx4 5.4 77,000 miles. when i slowly accelerate, i hear a rattle coming from somewhere under my truck. like if your in the drive thru and your slowly accelerating, you will here a rattle or crackling sound....any ideas on what this could be, or does anyone else have this problem?

 

Could be all kinds of things, but if it's coming from directly under the truck, then it's probably from the exhaust. Bang on the cat's with your hand (when it's cold ofcourse). Sometimes the heat shield attached to them gets loose and rattles. Also check the exhaust hangers and connections.

 

crap! I get this sound too. I was thinking maybe transmission or driveshaft? Think I'll check the cats and exhaust. Pretty sure I'm not that lucky though. Sub'd.

 

yeah, i have banged on the exhaust and didn't hear anything, its weird it will also happen if I'm accelerating and then let off the gas pedal, it will make a cracking sound, its faint...but you can hear especially if you driving next to a wall, like thru and drive thru.

 

That's a good point about the driveshaft. U joints can make a rattle, but they normally make a deeper clunking type noise. They almost always cause vibrations. At least that's my experience. If you can park on flat ground, put the parking brake on and wiggle the driveshaft. You may get a small amount of play from the ring and pinion, but pay close attention to the u joints. You can't always tell if they're bad that way, but it doesn't cost anything and it can't hurt to check.

 

Does it kind of sound like a car trunk / license plate rattle from a subwoofer shaking it type noise? Heard somethin like that come from mine the other day when cruising in a parking lot at slow speed. I was thinking it may be coming from exhaust shield or IWE hubs. Was hard to tell what area it was coming from... Sounded like right side for me

 

yeah thats what it sounds like kinda, only under light acceleration and low speeds.

 

Have u tried checking exhaust manifold? From reading on the forum it seems like passenger side exhaust manifold is notorious for rusting out/leaking. Im hoping this isnt the case for either of us... Will try and check mine this weekend.

 

Mine has got progressively worse. It now happens almost all the time at low speed when accelerating and turning. It sounds like its coming from the back - i think it is the clutch plates in the differential. Does yours vibrate / shudder too at certain speeds

 

Mine makes all kinds of scary noises while in a drive thru. Scares the crap out of me for a while, gives me nightmares but it still runs strong. Mine are coming from the valve train. I think they're just noisy.