Hi all,

My 2004 F150 5.4 2WD TRACTION LOCK has 120k on it. I had a rusted differential cover and some very minor leak on the pinion seal. Took it to my local repair shop and they replaced the cover and seal. I drive 50 miles highway each way to work every day.

After the repair I slowly begin to notice a whine coming from the rear. It was minor at first but after 4 weeks it has become more noticeable than the MBRP dual exhaust. I took it back to the shop and they referred me to a differential shop saying it must need bearings and they won't go into it.

When I called the Diff shop I told them the whole story and the first thing they said is it was likely the pinion nut was over tightened. I've got an appointment later this week. But since I have good luck with the local shop I let them have another look before taking it to the specialist. I shared with them the likely mistake and wanted to give them a chance to confirm they didn't screw it up.

Maybe a little foolish of me to trust these guys but they have been very good up to this point. In my mind I am totally convinced they screwed it up.

Anyone have similar issues changing out the seal?

 

So nobody here has had issues with their limited slip diff?

Here's an update. The shop took it back and replaced the front pinion bearing. They had to order a special torque wrench to do the job. Been sitting there over a week. Got it back and the noise is actually louder and much worse. Very disappointed. Just wanted some minor leak fixed and now looking at a total differential rebuild.

 

Around 50 MPH mine has a whine upon acceleration. Let off it goes away. I am waiting for it to become an issue before spending more money. Put plenty, 6000 dollars in the last two years, into this thing already!

 

I would see if they put the right Diff fluid in there.

 

...More to the point, did the shop add the friction modifier required for the traction lock differential? If not, add that and maybe the problem will be solved...

 

Mine has a slight wine at 50 mph too. I'm gonna let it roll out as long as i can. I figure it might go 150-200k miles with no problems...

 

+1 on too much pre-load on the pinion bearings. it's almost impossible to use the 'wrong' diff fluid - there is such a range on what will work in one of these rear ends. and if it's a posi then without fric mod you'll get a binding or popping from the rear end, especially on tight, low speed cornering.

you're complaining of a howl at speed and that will be the bearings and/or the crown and pinion.
- if the howl worsens when you are on the throttle and lessens when coasting (this is all at higher speeds) then it's time for new pinion bearings. this is caused by over-tightening the pinion nut after replacing the seal.
- if it's totally proportional to road speed and not engine speed then it's side bearings

have fun.

 

Varsity, what if you just keep driving it?? Mine has howled for 20,000 miles probably. Or can this nut be loosened? Or re-torqued? Or is it too late when it is in "howling" mode?