I don't know much about the inner working of the rear pumpkin, but my 4x4 with limited slip is giving me a fit. It started our more sporadic, but now, anytime i turn, I can hear it catching and making a reverberating noise. I had my local mechanic drain the factory synthetic, clean everything with chemicals and re-lube with synthetic. He also added the friction modifier as the book calls for. The problem seemed a little better for a few weeks but is now worse than ever. Ford says they have had problems with the limited slip but mine is out of warranty.

Anyone have this problem? Any suggestions?

thanks

Oh yeah, forgot to mention, i brought the truck back to the mech and he added a second bottle of the modifier, which did not help. If racer is right, might be time for new clutches. How expensive is that route?

 

If new oil and friction modifier didn't help you will probably have to replace the limited slip clutches. You could first try adding another bottle of friction modifier and see if that helps.

 

Your clutch packs are toast. The noise you hear is because they are not sliding past each other but grabbing instead. Which gives you the rumble you have now. I haven't seen a cost on this.

 

I have the same problem, but it appears to be worse as the temperature rises. Right now, with low temps in the midwest, it is not objectionable.

I have purchased new Ford synthetic diff fluid and a bottle of the "magic" friction modifier, but have been waiting for warm weather to install the stuff.

Are there any consequences to waiting? What happens when the clutch packs go? Is it just an annoyance, or is it undrivable?

 

I will know a lot more later this week. Incredibly, i called my dealer and he offered to cover it through the ford loyalty program. This means I pay 25% and ford will pay 75%, despite being out of warranty. This situation has been a big problem for ford and they (or at least my dealer) is making a point to take care of me. I hope they replace the clutches but they may only replace the fluid for starters.

 

Replacing the fluid is a waste IMHO. That synthetic stuff is not cheap and if your going to open the pumpkin - fix the problem.

 

I have a suggestion for your problem... after spending almost 20 years as a Ford dealer parts guy the only limited slip lube that our service department would use and stand behind was the Ford Motorsport pn# M19546A it is different than the regular Ford pn C8AZ-19B546-A. The Motorsport lube is a dark purple color and man does it smell bad !! you can smell it right through the bottle without opening it. Our service manager said the smell is what makes it"work". We had trucks come in with chattering diff clutches, we changed the lube and added the Motorsport additive and within a few miles no more chatter. Give it a try before you pay for new clutches.

 

picked up the truck today from Ford. Despite being out of warranty, they covered the cost for new clutches, labor and new fluid. I had to pay 25% or $130. It reverberrated for a few miles, but once the fluids coated the clutches real well, it stopped. Haven't driven more than 10 miles, but seems to be fixed.

Ford, or I should say, the service manager, really stood behind me on this one.