I read a few earlier posts about the rumbling noise coming from the rear end in order to determine what was wrong with my truck.
Today, I finally went to the dealer regarding the rumbling noise and I wanted to share the info I learned regarding my 2006 Tacoma. This noise just recently started after having the dealer service the differentials and transfer case at approximately 40,000 miles. Currently, I have 43,000 miles on the truck and everytime I make sharp turns and hit the accelerator, the truck makes a horrible rumbling sound, almost as if the rear differential has a severe bind inside.
After continued driving, the truck also made the same noise in reverse. I decided it was time to go to the dealership today. Fortunately, the dealership replicated the problem with ease. In fact, three different mechancis took the truck for a test drive to try and determine the issue at hand.
After nearly an hour of waiting, I was informed that the dealership was on the phone to Toyota of California (apparently the technician help line). This was simply because they could not determine the fix for this issue. Eventually, the service advisor informed me that Toyota of California recommended that 2 additional bottles of friction modifier be added to the rear differential and that this rumbling noise is "normal".
After hearing this, I disputed the "normal" comment, however I figured I need to jump through these hoop and see what happens. Keep in mind that I have nearly 15,000 more miles of powertrain warranty, or a little more than a year left. So, the dealership added the 2 additional bottles of friction modifier and now the rumbling noise is gone. To be honest, the rear seems to be very smooth now.
I will say that the dealership told me they will not guarantee this fixes the problem, but it is worth a try. This is because Toyota will not simply replace the rear end on the truck without a little bit of troubleshooting.
My frustration is that none of this happened until after the rear differntial was serviced. And, I know for a fact that friction modifier was added at the time of service because the service advisor informed me of it upon handing me the invoice for the work.
I am hoping this corrects the problem. From what I understand, if it reappears, it will do so within about another 4,000 miles. Let's just hope this provides some of you other Tacoma owners with some dealership advice.
I am so happy I had the Toyota dealership do the differential fluid change. That was the first concern of theirs...the fluid needed changed. Too bad it already was changed...by them!