Hey fella’s. New to the forum so hopefully I’m not breaking any rules...
I have a 2011 F250 super duty crew cab. 6.7 diesel. The truck has an 8” lift and 39’s on it. I’ve oaned it for 3 years and tow frequently with it.
Wanted to run a scenario by the forum and see if I can get a diagnosis. I’ll try to give as much detail as possible.
Yesterday I was driving along a pretty beat up (pot holes) road, towing a duel axle 14’ dump trailer, weighing probably somewhere around 5000 lbs. I do this almost every day, the load I was towing was no different. I have a 10” drop hitch that gets the trailer sitting nice and level right where I want it. The load was dispersed evenly across the whole trailer.

as I was driving down the rough road at about 35-40MPH my steering wheel suddenly started rocking back and forth. I’m not talking a little wobble, I’m talking complete loss of control, rocking about 45 degrees very quickly from side to side. I quick slammed on my breaks because I literally could not hold my steering wheel still and I veered across the center line and almost ended up in a ditch. Once I got down to 10MPH the rocking stopped. I pulled over, visually checked my tires, lugs, steering, etc. visually everything looked ok. I called a mechanic friend and he said to check the steering dampers if they’re broken or leaking, they both look fine. I had a guy rock the steering wheel back and forth and I couldn’t see any visual play or rocking in the wheels. I got back in my truck and started up again and no problems whatsoever. I was a little scared to get up over 35-40 again and took it a little slower the whole way home. But I drove about 10 miles with no additional problems.

Any idea what may have caused this sudden steering loss?
I should also add, the road I was driving was rough but no deep holes. And I didn’t hit a hole when I suddenly lost steering.

 

You didn't specifically mention checking the truck's power steering fluid level. Did you do that?

 

 

Check your steering knuckle u-joints, they can bind and cause that exact problem, it can come and go depending on how bad they are. If you are in 2 or 4 wheel drive as long as the hubs are locked it can occur. Jack up the front end and try to turn /steer the front wheels, turn the wheels until the cross on the joint is parallel to the ground and "steer" them left and right, if they are not bound up turn the wheel 90 degrees and try it again.

 

This is called death wobble. You need to check front suspension components to make sure they're still tight. ESPECIALLY the track bar on BOTH ends. Even the slightest bit of looseness will cause this. After all that you might want to have your tires rebalanced.

No steering fluid needed unless you're having problems turning the wheel when stopped.