08 T4R Ltd.bad rear diff

[KB084RUNNER]

Noticed a tip in throttle harmonic whine at 60-70 mph last Spring and took it in to the dealer (7000 miles). They said they heard nothing. Over the course of the year it has gotten louder so I took it back with 17,000 miles and they could hear it and put a microphone on the diff and sure enough...it was whining more than normal. They ordered a new complete rear diff assembly and installed last week. So far no noise but I am taking it easy for 500 miles to avoid over heating while the new gears break in. The dealer tech drove it 15 miles on the freeway and said no noise.

I have my fingers crossed........ :moping:

 

[KB084RUNNER]

Got it back with the new diff in and now it whines on decel just a bit. The tip in throttle whine is gone but the new diff is hardly quiet. Not impressed. I will change the oil at 500 and run 80w90 dino until 5000 and if it still whines take it back again.

 

[004Gunner]

Over the course of the year it has gotten louder so I took it back with 17,000 miles and they could hear it and put a microphone on the diff and sure enough...it was whining more than normal.

Seriously? You have a dealership that will mic for diagnostics? That's bada$$! Any idea what was wrong with the old diff?

 

[KB084RUNNER]

Seriously? You have a dealership that will mic for diagnostics? That's bada$$! Any idea what was wrong with the old diff?

They are a Penske dealership and really know their stuff. I don't know what the problem with the old one was but they did send it back to Japan for inspection. The new diff has 3000 miles on it now. Did the oil swap at 500 with no big metal boogers on the magnet (thankfully) and now it seems to be getting a bit quieter. I'll run the dino to 5000 and then switch back to Mobil1 and see what gives.

 

[004Gunner]

The fact that it got shipped back to Japan for inspection is good news. My understanding is that Toyota would do this as SOP for unresolved diagnostic issues, which is partly why their reliability was top rated. Maybe your diff just needs a break in period.