I have a 2004 F150 Lariat SuperCrew and I know this has been discussed at length and I have read a ton of posts about the issue. Sadly, I can't seem to find one that matches mine exactly. Just recently I started noticing a "howl" or "whine" from the rear of my truck, at any speed, whether I'm accelerating, coasting or braking.

I just put new tires (BFG A/T) on the truck and had the transmission rebuilt about 3 months ago. I honestly just thought it was road noise from the tires but the fact that it is only coming from the rear is what makes me think it is in the rear end.

From what I've read it's likely the pinion, carrier bearing and/or the seals but seems to be a VERY common occurrence with 04's. Some people claim to have driven the truck with this howl for 50-75,000 miles. I have read where some people recommend changing the diff fluid to 75w140, which I plan on doing very soon.

Like I said, I have never noticed the noise before but that doesn't mean it wasn't there and I just ignored it.

My question being- Has anyone had this SAME issue and what was your resolution? Seeing as how I've dumped $3g into the truck in 3 months, how long will the rear end hold up?

Any advice is GREATLY appreciated.

 

I wouldn't push it! climb under your truck on level ground in N and give the drive shaft near the rear diff a yank side to side and forward and backward. see if she shakes. I would also pull the cover and check the mesh pattern between the Ring and Pinion. You should be able to see this on the face of the ring gear teeth. If its not centered in both directions you will know.

The longer you wait the more expensive its going to get. If you good with tools and precision measuring you should be able to load in a new ring and pinion gear as well as new bearing.

You're sitting on a time bomb. Get a shop manual (a real one not a crap one) and go get your hand dirty!

 

Thanks for your response however there is no play at all in the shaft, I checked this yesterday. It's very sturdy. Does this mean the gears should be solid?

 

Ok, so there was no movement in the shaft in-out or side to side. The only way it moved was the natural rotation and it was only maybe 1/8 to 1/4 of an inch, if that. So that that help with anything? I'm new to Anything RWD-4WD, I've had imports most of my life. So the whole rear end is still a bit foreign haha.

 

I have a very similar issue except my whine stops when I let off the gas. Did you ever solve you problem?

 

Service the rear diff..do not forget friction modifier if you have a limited slip..