I have a 04 FX4 with 82 thousand on it and when I drive down the rode between about 45 to 55 there is a howl that comes from the rear end. Its beening doing this for about 1 year now but it drives me nuts everytime I get in it. Thanks

 

Have you checked the fluid level? From what Ive been told, thats a warning noise that something isn't right.

 

you prob need the rear end worked on ,mine does the same thing,i thought it might have been cause the diff was leaking,so i got the gasket replaced and put new oil in but nope didnt solve it ,now i am thinking i gota bring it in for some expensive work

 

Just curious... is this an 8.8 or 9.75 rear end?

 

my truck has been doing this for the past 3 yrs now...

 

The fluid is full I have checked and when you pull out the top plug oil does come out. I have never changed it and doubt the previous owner did. I did drive it on a 6 hour road trip and noticed a little oil puddle where I was parked but never leaked after that and its been 4 months. I just get annoyed when I hear any little noise on vehicles. It has the 9.75 with 3.73LS. I guess I should start saving to bring it in.

 

is the noise present at all times or just under load?

 

my 2003 FX4 screw does the same thing .. I have the 373 rearend.. And I am going to let it whine.. The local shop wants 900.00 to open it up and fix the pinion...

 

Yes its all the time. I can actually hear it over the radio and the exhaust si/so super 44 not like its that loud but still just don't want it to go out when I drive over a long distance. I think I might try changing the fluid when I get time.

 

if its all the time its definatly a bearing. The pinion bearing cups are bad for pitting i suspect this is your noise.

 

I had a whine/roar in my 74 Ford station wagon years ago. I thought it was the tires. It sounded like tires with bad belts. Then I checked the rear brakes and found the right rear axle seal was leaking all over the brakes. So, I tore the rear apart. The problem was the outer pinion bearing. I cleaned it up and reinstalled the gears with one new pinion bearing and it worked great. It did have a tiny whine when decelerating but I was happy with my shadetree job.

If you ignore it too long, both the ring and pinion gears will have to be replaced.