I hear a loud metal on metal sound when backing up in 4wd. The sound seems to be coming from underneath and closer to the front than rear. It happens only while moving in reverse (under power or coasting) and only in 4wd. Never occurs while moving forward. The sound is similar to that heard when brake pads wear down to the backing plate.

Any ideas, folks?

Andy

 

not to hijack but I am interested in this too as my '02 King Ranch does the same.

 

Hey, no problem.

Funny thing:

I had to move the truck last night in 4WD Lo (severe ice storms blasted through here yesterday and last night). I shifted from reverse to drive just slightly before coming to a complete stop, jerked the driveline a bit, and the noise ceased.

Not expecting it to be a permanent fix, but I thought it was noteworthy.

Andy

 

Had this issue resolved today after chasing it down for 6 months. Was the front u -joints. Repaired under the powertrain warranty. As per paperwork...replaced front u joints (2) part # 4L3Z-4635-A.

This is on an 07 f-150

 

Well, good news! I had new tires put on today, and while it was up in the air, I inspected the area around the front drive-shaft and found that the transmission vent tube had fallen, and became wedged between the drive shaft and the cat-con heat shield. The metal clip which was supposed to hold it in place (somewhere), was up against the drive shaft. When it rotated one way (forward), it "pushed" the tube and clip out of the way, and in the other direction, it "sucked" it in and rubbed. The line must not have been secured when the trans was re-installed after a rebuild 1+ years ago.

I zip-tied it up as high as I could reach for now, until I find out where it's supposed to go.

Yay!