calling all noise detectives

[IkeH]

I have a 2003 Mountaineer V6 AWD with almost 90K miles on it, and I am getting a weird clunking noise that is somewhat intermittent.

Here are some details on the noise:

Sound:

• Clunking sound that is loudest at low speeds, but persistent up to ~65 mph.
• Gets faster/slower when accelerating/braking.
• Sounds like it is coming from the drivers side front wheel, but sometimes also sounds like it's originating from the center-front of the vehicle. Almost like it moves around a lot.
• Sometimes there are days where it's more like a minor clicking sound, and other times it sounds like a very loud clunking sound.

When:

• Occurs both when the car is in gear or in neutral, but only when the car is in motion.
• After driving for a few minutes above 65mph, the sound goes away completely. No clunking even at slow speeds if I've spent a few minutes on the highway.

Curiosities:

• Sound first made it's appearance after a day of heavy rainfall (about 3 weeks ago) and flooding. On this day, I could not make it into work due to flooded roads...had to turn around and drive home. The next day, I noticed the noise.
• At that time, I took it to my mechanic, but since I had to get on the highway to get there, the noise went away while driving to his shop. He says he checked the drivetrain and suspension for any play, and everything looked fine. He did notice at the time that my rear brake rotors were below the minimum thickness and we did replace those.
• The second time the sound made an appearance was again after driving through heavy rains (about a week ago), this time on my way home from work. The next day, the noise returned.
• Again though, I got on the highway to go to work after hearing the noise, and by the time I got to my exit, there was no noise.
• The sound made it's third appearance today on the way to work. I do not think rain is the culprit here, because I was gone all weekend and the vehicle was parked in a garage at the airport. There was no rain last night, and I did not notice the sound driving home from the airport. I first noticed the sound on the way to work in a traffic jam on the highway, after having to brake hard to avoid hitting another car that cut me off.
• And true to previous experience, once that traffic jam ended and I was able to get up to highway speeds, The clunking went away, and was nowhere to be heard after exiting the highway.

.

Anyway, thats what I know about it so far. This vehicle has had some other problems in the past year. I bought it with a bad/frozen transfer case. (that the dealer wound up replacing, along with the tires, but only after they had rebuilt the front differential twice).

Any help on this one would be hot. Whatever it might be, I'd like to nip it in the bud before it has a chance to cause further damage to other components. I'm hoping someone here has had a similar enough experience to help me out.

Thanks.

 

[jrford]

gotta search on front wheel bearings. . . .very common to say the least.
outside chance rear parking shoes? but that would be a rear type of noise. . .