My truck sounds REALLY bad

2001 Ford F-150 Supercrew Lariat 4x4

I was driving last winter when something bad happened. I was on the highway in 4H doing about 45mph (Really bad weather). Suddenly there was a loud bang, like a shotgun going off. The truck continued to run but it sounded like someone was beating my driveshaft with a metal pipe. There is no apparent damage but it grinds and bangs when it drives. The engine runs just fine. I limped it back home with the noises being constant only when its moving. Please help!

You broke something in the drivetrain. It needs to be inspected by a mechanic to determine what is broken and what it will take to fix. This could be any number of things, like a broken driveshaft, which you should be able to see looking underneath the truck. This could be a relatively easy repair. If the driveshafts are intact, the problem could be broken gears in the transfer case or front and rear differentials. This will be a bit more expensive.

Please have it towed to a mechanic if you cannot get one to your house. Don’t drive this truck, as it could lock-up at any time and cause serious injury and much more expensive damage.

This happened last winter? The truck has been just sitting since then? Or, you are driving it in 2H and it is OK to drive?

I suspect you blew out something in the transfer case. Driving in 4H on the highway might have built up tension in the transfer case until something snapped.

Some 4WD systems handle driving in 4H on the highway better than others. If the pavement is just wet I shift out of 4H back to 2H until there is some snow or ice on the driving area of the pavement.

Yes the truck has just been sitting. Partly because the noise is so bad and loud that im afraid something bad, like pole vaulting a huge truck, will happen. I am saving up enough money for the worst case scenario.

If you were in 4HI on pavement, even wet pavement, then you probably broke something in the transfer case or possible broke part of the front drivetrain, a CV joint would get my vote. The only time traditional 4WD should be used on pavement is when the pavement has snow or mud on it.

Yep all good advice. You also should be able to determine the condition of all of your U-joints relatively easily. My guess is that it is one of the front U-joints…because that shaft is not used until you engage 4WD and sits idle most of the time…the -U-Joints dry up or worse Rust up and when you engage them and use them they tend to snap…this will throw your shaft off its normal balanced rotation…lots of noise but an easy fix most of the time. The other thing is your locking wheel hubs. Id leave the X-fer case for last…they are fairly robust and you didnt do anything really to hurt it. My guess is the u-joints in your front axle…and or driveshaft…check them first…you may be pleasantly surprised to find one damaged…and an ez fix.

Thank you guys for the advice. When I get a day off Ill slide back under the truck and take a look.

ok so climbed underneath the truck. there is a little play in the driveshaft where it connects to the rear diff. how much play is normal!? I plan on taking the driveshaft off tomorrow to see if its a seizing issue. Any thoughts?

I once had a Ford Bronco II that had almost the same thing happen, and it turned out to be a busted U joint. Hopefully that’s all it is for you, as it is a cheap and easy fix. Good luck!