Having never experienced a U-joint problem, I am not sure if this is a U-joint issue or tranny related. (I think it is u-joint) I have a "rotational" clunk. Sounds a lot like a weight on a shaft is sliding from one end to the other when it rotates. Only does this when the driveline is engaged. Does it upon acceleration and coasting. Sound is louder at slow speed and goes away at higher speeds (i.e. the roataion of ____ does not allow ____ to move around) If i put the tranny in neutral, then sound is gone. Happens in all gears. Tranny fluid is fine, no leaks, etc. I do not know how to test a u-joint, so not sure about that.

So, tranny or u-joints?

 

A couple of things. With engine running and foot on brake at idle shift from drive to reverse and back. A clunk could be u-joint.

Block tires on flat ground so vehicle can't roll. Put on emer. brake. Place transmission in neutral. Grap driveshaft close by u-joints and shake left and right and up and down. Must be tight.

 

I would look at the U-Joints too! The steps suggested should help you check.

If that is not it, while you are checking the u-joints, shake the pinion too. The pinion is what the rear u-joint connect to.

Good luck

 

Definitely u-joints.

 

Its the u-joints, well at least the front. I thought it was, but was not able to shake it when i tried (that was before I read it has to be in neutral ), after I read that it shakes.

Gonna replace both, thanks for the help.

 

i'm having the same symptoms.

there's a popping noise within the driveline; coming from the front and it's reverberating THROUGH the driveshaft, making it sound like it's coming from the driveshaft itself. my buddy says it comes more from the front of the truck so the source might be there.

popping noise only happens under load; ie in drive or reverse and at a standstill and only on occasion. it's not continuous.

motor and trans is said to have been rebuilt recently.

i was told it might be the front U joint.

how much does a new U joint go for and how hard is it to replace? i am mechanically inclined so whatever it is i should be able to fix it.

also, does it matter what year the truck is? cuz mine is a 89 150 with the 302 and RWD.

any updates would be great!

 

U joints are cheap. Round $15 to $25 each depending if you greasable or not. I had to get a shop to do mine b/c I could not get the caps broke loose on the rear joint. They had to use a press to get it done. Hardest part is the caps. The one that was loose was easy, but the other was hard due to some rust build-up on it.