I have a 2005 F150 FX4 4WD 4sp Automatic 5.4L V8.

Problem - Bad sound coming from presumably the transmission, but possibly the xsfer case as well. Sound is not high pitch like a belt, more like a fast scraping sound.

What I was doing - I was towing a Jeep on a trailor about 200 miles. Roughly 100 miles into the trip I head the sound. I pulled over checked under the vehicle and in the engine compartment. Transmission was about 2 quarts low on fluid (I imagine that it pretty low). I filled the tranny up and the sound persisted. The sound is non existant until I hit 2000 RPM and is present until 2500 RM and is back around 3000RPM. attempted to put my truck in 4Hi and 4Low with no success. I ended up making it to my destination, the truck sat for a could days and it was time to drive it home. Truck now goes in 4Hi and 4Low. The sound goes away if it is dirven in 4Hi and comes back in 2WD. Everything happens at 2000RPM.

Any previous problems similar to this or thoughts?

 

Sounds to me like your planetary gears are shot. Start saving for a new transmission.

 

AAMCO seems to think it is likely a U-joint in my drive shaft may be the cause. Makes sense that the more power that is delivered to that joint the sound I am hearing would be audible. When in 4wd power would be distributed to both drive shafts and alleviate the rear.

In all reality odds are this is way to easy and cheap to be the solution.

 

Scraping sound that goes away when you engage 4wd is a sure sign of IWE issues. Search away on this topic as it is very common with our vacuum activated front hubs.

 

I was told about this by a off road shop. That was the reason I tried shifting back and forth from 2WD to 4WD. Ill look into it further. Luckily AAMCO is looking at my truck for free, and hopefully I can fix the problem myself or find someone cheaper.

 

I would check the oil level in the transfer case. Apparently the rear trans seal can leak. Thus filling the transfer case. That could be where your 2 qts of trans fluid went. Seeing how the transfer case is only suppose to hold 2qts it could be pretty full.