I bought my '01 F150 Screw with around 100,000 miles on it. The previous owner(s) had it serviced at my same dealership so I have some of the maintenance/repair history. Both the left and right rear axles and seals have been replaced on it before I got it, and I had to replace the right one again after I had it (it had a grove where the seal rides and had some rust there). The other day I was looking at the manuals and noticed that a Marina used to own my truck and am wondering if the axle trouble is a result of going in and out of the water? Is there anything I should do/check because of this? I did see in my maintenance book from Ford that you should change the axle lubricant if the axle gets submerged in water. I'm assuming that was done when the axles were replaced.

Possibly related, I do hear a knock from the back sometimes when my truck goes over a big bump unevenly (e.g. driving over a driveway curb at a diagonal). Any thoughts about what this could be?

 

If the fluid was replaced after being immersed, assuming the marina went in that far, then it should not be a problem.

As far as the thump or knock in the rear, make sure that all shock bolts are tight and make sure the spare is cranked up all the way and is not loose.

 

I checked out the shocks and the spare and both check out ok - all tight. I'll maybe have to sit out by the drive way while my wife drives to see if we can reproduce it while I'm out there.

 

My 97 makes the clunk when driving into the driveway over the hump. Also does it over rough terrain. I asked the same question here on this site. Everyone says its normal, these trucks pretty much all make the same noise ( to varying degrees) when driving over the curb, rough ground etc. I wouldn't lose any sleep over it.

 

curbing it will make the rear clunk, i believe its a few thousandths that each axle shaft has for play laterally before it touches the pinion shaft in the carrier? but to be safe, check your drive line to companion flange bolts.