Hello, This is my first post on the F150 forums as I just recently purchased my first Ford. I recently purchased a 2000 F150 with 150k miles for my son's first vehicle. The truck ran flawlessly in 2WD and 4WD with the exception of a subtle increase in vibration and drivetrain hum when in 4WD. The 4WD engaged and disengaged smoothly up until my son was driving in our neighborhood and hit a patch of ice going approximately 20-25mph and spun out and then slid sideways into a curb on the passenger side. Ever since the truck runs fine with no increase in noise or vibration in 2WD, however in 4WD there is a distinct rubbing noise accompanied with quite a bit of vibration and the 4WD will not disengage without stopping and going in reverse.

I have removes the tires and visibly inspected the front hub and axel assembly but I do not see any visible damage. I'm assuming the front hub assembly was damaged when the tire impacted the curb. Does this sound like a damaged hub assembly and would a damaged hub cause the 4WD issues?

Thank you very much in advance for any help you can provide..

 

I was betting on a bad hub/bearing before I read the information, now I'm more convinced that it's FUBAR. It don't take a lot to mess up a front bearing when hit from the side. That's where I'd check first thing. These aren't that hard to remove, since they keep the mud out, and make it fairly easy to swap out.

 

Thanks for the quick reply akdoggie, my assumption is the same. Althoigh, for the sake of troubleshooting, if the front bearing was damaged shouldn't I also be experiencing the same vibrations and a rougher ride whether I'm in 2WD or 4WD? Thw reason I ask is in 2WD everything feels normal and as if nothing happened. Do you have any idea how or why a damaged bearing could also prevent the 4WD from disengaging?

Thank you again for your help..

 

As far as the 4wd engaging and disengaging you need to figure out if it is in the axle or t-case. Chock the rear tires, sit the front on jack stands, engage 4wd and make sure it locked in (In Neutral or Park only) . Then try to disengage it. You can tell if its disengaged by trying to rotate the front wheels by hand. If they dont turn then it didnt disengage at the axle. This will help to isolate the problem.

If you have it up on stands you can go ahead diagnosing and replacing the front hub assembly too.

 

Thank you for the troubleshooting tips. That gives me a place to start. I'll be diving into more this weekend to see what I can find and will report my findings.

Thanks again!

 

My .02 ----

Can you see the vacuum solenoid engaging and disengaging the front axle?

There may be a plastic cover over it, but I'd have someone go in and out of 4WD while watching that. If it moves correctly (it has a pretty small stroke, btw) then you probably have a jacked up fork or pads inside the diff. EDIT: Found a pic of my spare diff. I circled where the vacuum piece mounts, as well as the lever it moves......

 

Right, probably snapped the fork when it hit, that don't take much either. Actually the forks plastic bushings broke, they go first usually. But yea, check the actuator movement like white suggested. It will move back and forth when engaging and disengaging in the cab. Have someone work the switch while you watch for movement under the truck.

I'd probably do that first, then bring it up off all fours like jp mentioned...how ever you want to do it.

While you have it in the air, slide your leg or foot under the wheel and take some weight off it. At the same time grab the wheel 10 o'clock 5 o'clock and check wobble or play. Try other positions as well. There shouldn't be any slop in the bearing.