When I am going slow, almost coasting, I am pushing down on the accelerator very gently, just enough to keep the coast going like around 25 in school zones or neighborhoods. I hear a metallic rattling which sounds like it is coming from near the bottom middle portion of the engine. Does anyone know what I am talking about? Its a 4.6 06 xlt

 

If yours is 4x4, engage it at the same speed and see if the noise goes away.

 

forgot to add that, no 4x4.

 

Does it sound like marbles in a can?

 

thats a tough Q? It kinda sounds like that if the marbles were metal. Does that seem crazy

.Ok if you take a can and metal marbles and kind of whirl the can so the marble roll around the can. That is what it sounds like

 

Sounds like a bearing is about to take a crap on you. I just replaced my Tensioner Pulley because I was getting the same sound. Try to pin point it with the hood open and than take off the "suspected" pulley and spin it on your finger. You will be able to tell good or bad by the sound it makes. I checked both idler pulleys before I got to the tensioner, if its not the first one you take off try the next one.

 

Mine does it too check this thread out:
https://www.f150online.com/forums/sh...d.php?t=325765

 

Mine does it too... Been trying to find the cause for about 20,000 miles, including having the dealer replace the cam phasers. Still makes the same noise.

 

I would think if it's the engine pump or pulley you'd hear it without driving. Just rev the engine at the engine with the hood up and listen.

 

That sounds like a brake dust guard rubbing on the rotor to me. It's worth a look.

 

Definately not a rotor/dust guard issue. The noise is also present when not in gear (P or N). Rev it up to 800-1000 RPM and it happens.

For me, it sounds like its coming from the back of the engine, or further back (tranny, exhaust manifolds, etc).

 

Mine is identical to what you are describing. I plan on taking my in to the dealer in the next couple of weeks when i have spare time. I've only got 1100 mile left of the 36k warranty. I've also got the start up rattle as well so i hope to get it both taken care of in one trip

 

Be sure to keep us posted. Obviously, my dealer wasn't able to get it fixed. So I'd definately be interested to know what the heck it is.

I've even gone as far as putting the truck up on jack stands, and using a broom handle wedge between the seat and the accelerator to keep the RPM's at the right range. I've crawled under and over everywhere I can get to, but I couldn't isolate the noise.

 

Look underneath and make sure all your heat shields are tight and none of those bendable shields are touching or close enough to rattle against anything.

 

My truck was making the same noise...took it to a buddy it was bad piece of tubing around the hub. When you accelerate the tube is like a vaccum and makes the noise. Mainly fixed the problem but hear an occasional sound like before