Drivetrain sound and vibration

[werkenklasse]

I have a 2001 F350 CC LWB 4x4 Auto Lariat with 195K miles. Recently, I had the truck come back from the trans shop after a repair. The truck now makes a constant noise coming from the drivetrain. It sounds like a small grinding noise. I have also noticed that while on the highway at 70mph when I take my foot off the gas just enough to get to that neutral point of letting the truck coast and the drivetrain pulling it, there is a noticeable vibration and sound. Sounds and feels like I am driving over a really bumpy road. Not sure what it could be. Any suggestions?

[JPOWERStroke53]

I would love to know what causes this. I have the exact same problem with my 02 F250

[NoRalPh]

In a 4X4, the first thing I would do is to lock the front hubs IN. You don't need to be in 4WD, just want the hubs locked so they turn the ft. axles. This eliminates the need for the small needle bearings in the hubs to turn. They often cause noise that sounds like you're driving on the Rumble Strips.

It's an easy test and a cheap fix it that's turns out to be the problem...

[dieselcrawler]

you might check the drive shaft yoak bolts, I have had these come lose, I think it's a 12 point, 12 mm bolt that holds the drive shaft to the output flange/yoak on the back of the transfer case if it's 4x4... not sure about a 2wd, they might be a slip yoak style, and in which case, what I've said is null and void.

[desertdeer]

what kind of repairs? these trucks have 2 peice driveshafts and if they are taken apart the have to be put together the same way or they are no longer balanced. also the slip yoke should be greased regularly. it takes a special grease made by motorcraft

[Galaxie]

1. Ensure drive shaft went in like it went out. Or it could be grossly off balance.
2. Agree, lock in hubs and see what happens.
3. U joints.....
4. U joint bolts tight.
5. Inspect carrier bearing
6. Bet a 6 pack the drive shaft wasnt marked and put in different.

[werkenklasse]

I had all the u-joints and slip yoke replaced on the front end (4x4). The rear driveshaft is where I believe the noise is coming from. I have heard some guys say it is the carrier bearing. I may just go ahead and replace both carrier bearing and all ujoints.

[werkenklasse]

You mean the driveshaft was put in backwards?

[machete31]

I have same noise when coasting also, if I am accelerating/deccelerating or cruising no noise. Report what you find. I am also leaning to the carrier bearing. Any way to check the carrier bearing?