smithka

I have an '04 5.4 Super Crew 4x4 and I'm experiencing a strange noise coming from the rear end. It is a "rhythmic" rubbing/clunking sound that seems to associated with the speed of the vehicle. But there are a few things that lead me to believe it is associated more with the motor:

-It is not as loud/fast when coasting down hill
-It is not noticeable at all when starting up a hill from a stop (high RPM, low speed)
-it is less noticeable once I am on the highway with the cruise set around 60mph.

Is is possible this could be a U-Joint? I believe my U joints are of the "pinned" variety - so that is something that I don't want to tackle unless absolutely necessary.

Thanks!

gone postal

Does it "thunk" when going from park to reverse or reverse to drive?

smithka

I have not noticed that when shifting into reverse or drive, but I will pay a little more attention from now on. Would that indicate a U-joint gone bad?

gone postal

Yes.

Also, if you have the staked u-joints with the WONDERFUL factory shaft, best bet is to either replace it with a junkyard shaft with replaceable joints (about $150) or buy a new shaft.

primalurges

The clunk when you put it in hear isn't necessarily abad u joint can also be slip yoke that needs lubricating. I doubt it's a u joint however of it is you will typically see a lot of grease on the bottom of bed above the joint. The noise your describing hopefully has something to so with a binding e brake or rear brake caliper. It could also be your rear end and the reason you may be hearing it certain speeds and not others is the varying amounts of load applied at different times.

gone postal

The description of noises (less under low load, or no load (coasting)) high under medium/alternating stress and increasing with speed sounds like a U-joint or joints, which is why I asked about a thunk going into gear from a stop.

There isn't much grease IN the U joints, so unless it was a catastrophic failure I doubt you'd see much if any grease slung onto the underside of the bed.

smithka

Is there a good way to "test" the U-Joint before replacing it?

gone postal

With the truck parked, e-brake on, and tranny in neutral check for up/down side/side play in the shaft. There shouldn't be any. IN other words, the shaft shouldn't move in relation to the input yoke on the rear end or the slip joint on the output shaft of the tranny.

Pull the shaft and the joints should move smoothly on all axes of travel.

And resistance or sloppiness in the joint(s) and the shaft needs to be repaired(replaced, given the truck....)

Ifallsguy

you can repair staked u-joint. And much cheaper than you think. Check out this site as to how to do.

http://www.rockforddriveline.com/Sta...structions.htm

smithka

Well, I haven't had a chance to test the u-joint...but there is no discernible "clunk" when shifting into reverse from park or drive from reverse (other than the feel of the transmission changes gears.)

I have reevaluated the noise to be more of a "knocking" sound, and it is most definitely louder/faster when I am on the gas (even if it is just slightly).

Thanks for the help so far, keep it coming...