Just having a heck of a time trying to fix my 06 Ford Five Hundred. It has110000 miles. I recently changed all the brake pads and front struts myself. I had a little trouble with the strut replacement procedure and it turned out the passenger side drive axle was totally shot. I found a replacement at a local salvage yard and everything went back together fine. It drove fine for a while, but now I am getting a sound from what I believe is unrelated to the tranny. Around forty mph it is really pronounced and never changes the same rhythm. Sound becomes faster with speed. I have needed new tires for a while, but money is tight. Anyone have the same issue? I also replaced the water pump with an aftermarket water pump. It totally smoothed out the engine, but have heard there are issues with anything but motorcraft oem pumps. I was actually amazed at how bad the old pump was. You can barely spin it. I wish I could take it somewhere and get it fixed so I can stop worrying about it, but I don't have the money right now. It just seems like something new breaks every time I fix something else.

 

Welcome to the club.
Can you determine if the noise is coming from a particular area? Front, rear, left /right side, under the vehicle?
If it is tires and you want to do this switch tire positions and see if the noise moves to a different area.
If the problem wasn't present until you did the repairs, recheck your work and maybe the used part you installed was on it's way out.

 

I have replaced many parts on my 06 Five hundred Limited and let me tell you something. It just keeps going. Now I have to admit I have used primarily Rockauto economy parts except for spark plugs and wires. And I now have Mitchell1 so that helps but it just seems like the car is a ticking time bomb with the ridiculously priced transmission issue lingering. It’s a nice car in my opinion. Love the limited and it’s size and trunk space but honestly if you don’t have money to constantly put in it your in for a long road. With that being said I know your not gonna listen cause your invested like I got myself. So I would start with the tire rotation like buddy said already and then go from there. Keep us updated. Blessings to you and yours!