I'm hoping someone can help me out here before I take my truck to the stealership.
I've got an '05 F-150 FX4 S/C w/the 5.4 and 55,000 miles. When I'm accelerating in overdrive just to speed up I get what sounds like a rattling or grinding metal of some sort. It only happens in high gear, as soon as it downshifts, it goes away. Im wondering if its my exhaust rattling or if its the motor. Its pretty loud and its annoying the hell out of me. I've checked the exhaust and I havent found anything loose.
As anyone else experienced this? Any help would be appreciated. Thanks!

 

so let me get this straight, the truck has a rattle only in overdrive but when it down shifts and goes up in rpm it goes away? thats a tuff call. have you tryed beating on the cats with your hand for any rattle? are all the exhaust hangers in place? does it shudder or have any kinds of symptoms or is it just flat out a rattle?

 

Is the intake tube loose at the fenderwell?

 

are you losing power when it is grinding?

 

ive been under that truck 3 times trying to figure it out. ive shook the exhaust system-its tight. no shuddering of the truck just the rattle. it weird, its only when im trying to accelerate in top gear. its like once it downshifts and the RPM's climb it goes away.

i dont think its the intake tube- it sounds like metal.

i dont lose any power when it makes the noise. the truck runs great. thats why im leaning towards the exhaust.
would a heat shield make that kind of noise?

if i go from a dead stop and floor it, i dont hear any rattling noise. only under load in top gear. im tempted to record the sound and post it! its driving me freakin' crazy

 

Well, when my intake tube came loose it sure made a metal on metal sound.

 

x2!! Mine made a horrible grinding sound, I thought I was going to be out some major coin till i figured out that's what it was. Made the sound at low rpms, usually worst around 1200.

 

I had a sound like you are describing .I took my to the dealer ship they said that there was a problem with th 05 3.55 rearends they replaced it ring and pinion it the sound went away so I guess that was the problem did not cost me anything moght want to check it out good luck

 

Thats about the same RPM that mine is at when I hear the sound. At what part of the intake was it loose at? At the fender or the motor? I just couldnt imagine a sound like that coming from plastic, but who knows.....

 

I have the 3.73 rearend. So they replaced yours under warranty? Nice!

 

Ok, I just went out and tightened the intake tube. Its only 1 bolt? Weird.

I also reached my arm down and tapped on the idler arm tensioner for the belt and it sounds like the same sound. Just times that by 1000 while driving.

Any thoughts? Thanks!!

 

After hours of searching, I found that the noise is the IWE..? All I had to do was turn on the 4H and the noise went away!!

I may sound stupid but what is the IWE and can I replace it myself? Im pretty mechanically inclined. I just dont know much about trucks, Ive always owned Cobras.
I just dropped $590 on replacing my broken spark plugs and a bad COP.

Ive only had this truck for a couple months and Im puting WAY too much money into the dam thing!

Any help would be appreciated. Thanks!!!!

 

Watch the following video. It explains how the IWE works. It might not be the IWE. It has a spring that pushes it to stay engaged. A vacuum diaphragm pulls back against the spring to keep the front hubs disengaged. A vacuum failure will cause the symptoms you describe. Check the solenoids on the firewall. Check the vacuum lines for water intrusion.

regards

Jean Marc Chartier

 

I couldnt be ahppier right now. I just watched the video and now I understand how it works. (kind of a *****ty setup if you ask me)
Anyway, I checked all my vacuum lines and found that one of them was cracked and almost split apart. I also found that ther was no splitter coming from the solenoid to the 2 seperate lines for driver and pass. side. I found a vacuum splitter in my tool box, attached it, cut the cracked end off, plugged everything in and now, NO NOISE! I love easy, no$$ fixes like that.
That noise is horendous and I thought it was going to cost me more money to fix. I think Ill go enjoy a couple more beers! Thanks for all the help guys.

 

Where's the video?