I have a F150, 4x4, automatic, with about 150k miles, 5.4 litre. The truck has developed a rather loud clunk noise. It seems to be located underneath the cab. When I place the truck in drive and start to accelerate there will be one or two clunks or snaps. It's a very metallic sound. The noise also happens when I am idling down the street (say 20mph) and then accelerate. And also when I idle down just before a stop. It does not make the sound when operate the truck in reverse.

Things that have been checked:
All torsion mounts.
u-joints have been replaced.
Motor mounts are ok.
No noise when rotating the wheels by hand on a lift.

Talking with others, it has been suggested that the torque converter maybe loose. Does this sound like something to check? The transmission was rebuilt at about 100k.

I am located in the northwest -outside temps 40-50 degrees.

Any suggestion on what to do next?

 

Hi, my F-150 2x4 is doing the same thing. Can this item be described as "tin cans rolling on concrete?" I was also informed that it was the UJoints but im a bit unsure.

 

how are your shocks? i have one with blown out bushing and makes alot of noise....

 

check the slip yoke. remove the driveshaft and re-grease the splines that make contact with the output shaft on the transfer case. The slip yoke binds and does not slide freely. It seems worse for the harder your press the gas because the back suspension squats further, and forces the slip yoke to move. Ford has a TSB on this issue. Re-greasing should be done once a year. Good luck.

 

Take a look at your flex-plate and make sure your Torque Converter bolts are all in place and tight.

 

I have this noise and its very irritating.

Two questions? Is the slip yoke the flexible deal on the back tailshaft of the transmission? The transmission isn't going to leak fluid if I pull the yoke is it?

 

clunk

 

This is correct, especially with the 2 piece drive shafts, just make sure you use the Teflon grease, you can get it from for its not to expensive, i can get a part number if youd like

 

Ok, I'm getting the teflon grease and the clamps. Will I be able to pull the yoke out of the trans with out losing fluid?

 

Yes, no fluid should run out