Differential question

[Eltexasredneck]

Hello all,

I posted the following in the Transmission and Drivetrain section a few days ago but I haven't received any replies. So I thought I would post it here to try and see if anyone had any thoughts.

I have a 2004 Expedition that makes a grinding noise when I turn and accelerate at the same time. After doing some research it seems that it is the limited slip differential. So, I got some 70w-140 sythetic gear oil that said it had the oil modifier in it. Long story short, I miscalculated the amount I needed and thought I had put in enough even though it didn't run out of the hole. I know, I know, pretty stupid. Any ways, it wasn't any better and almost seemed to be getting worse. So, I ended up buying 8 oz of modifier at the local parts store, but not the Ford oil modifier. It was then that I discovered it was low on oil. So I also topped it off. It is now much, much better. However it is still making the noise - but only after driving it for a bit. So I am wondering if it is happening because the oil is thinning out once it gets warmed up. Is it possible I ruined that oil by possibly getting it too hot since I ran it a bit low? Also, since it seems to happen after the oil warms up, would it be ok to put in a 80w-140? Should I only use the Ford oil modifier, or is there one y'all would recommend.
Thanks in advance.

 

[08T1]

Drain and replace with a fresh batch of you favorite brand oil. Pour the modifier in first.

I have not changed the diff fluid in my exp. but many other vehicles with th LS. I use Royal Purpal or Amsoil. Just my personal preference.

If the fluid was too low for too long the clutch packs can wear groove in them. Make them chatter, growel and grinding noise.

As a suggestion maybe add two bottles of modifier. Then fill the rest with oil. I have done this a couple of time to reduce the chatter. Yes it worked.

Good luck!

CJ

 

[Eltexasredneck]

Hey CJ, thanks for the reply. I really appreciate it.

I will go ahead and drain/refill. I've never had a vehicle with a LSD and this vehicle had 156,000 miles when I bought it. Is a little bit of chatter "normal" with a vehicle of that many miles? I have no idea how much maintenance the previous owners did. If the clutches needed to be replaced will the chatter just get worse or is there something I should be listening for?

 

[08T1]

You should have no chatter. The extra bottle is there to help make it smooth out.

Adding the second bottle should do the trick.

Have fun!

CJ

 

[GMW468]

I've owned the same GM Musclecar for 30 years and I've changed differential fluid on it several times.

Here's the formula I have always used. Drain ands refill with a quality gear oil. I always use Valvoline products. I ONLY use the GM limited slip additive.

Then after a gear oil swap, take the car/truck out to a parking lot and do some figure 8's to work the limited slip additive into the clutches.

Several years ago I swapped out my 12 bolt rear for a Ford 9" and I followed the same formula. My 9" rear is behind a 600HP big block and I've had zero issues.

 

[08T1]

Yes very good idea.

CJ

 

[Eltexasredneck]

Ok, sounds good. Thank you CJ and Gregg for the replies. I really appreciate it.