New here. Question on rear-end noise when letting off gas...

[wreckop]

We have an '04 Explorer XLT. In the past month we've replaced a front hub, front axle shaft, and a u-joint due to what we thought was a noise from the front end (a 'whoosh-whoosh' noise as the tires were rotating)...could only hear the noise when letting off the accelerator.
(I'm female btw...so I'm sorry if I don't get all this right..lol, my hubby is a diesel mechanic and has been doing this work himself).
After spending so much already, I decided to bring the explorer to a friends garage so he could take a look. He was stumped at only hearing the noise when slowing, so he put it on a lift and sat in it with it running while his other mechanics took a look. He took off the rear driveshaft and the noise went away. They don't believe it's the rear hubs/bearings. He mentioned it could possibly be the pinion.
So my hubby took the exp to my bil's and put it on his lift, used his stethoscope thing, and definitely heard the noise coming from the pinion area. There are no leaks. He checked the gear oil and it was full of metal flakes/particles - so he drained it and put new (synthetic) gear oil in. It still makes the noise.

Any ideas or similar experiences? Does it definitely sound like the ring & pinion, or could it maybe be a pinion seal or other related part?

I've been stuck staying in town all summer with 3 kids because of the issues with this thing...don't dare to hop on the highway and head toward the ocean or anything! Thanks for any response!

 

[wreckop]

No ideas?

I see 30 have viewed my post, but still no response...no one else has had a similar experience with the noise only happening when slowing/letting off the gas?

Is there a better thread for my to post this on?

TIA

 

[matt0248]

IF he found metal flakes in the differential fluid that the differential needs to be rebuilt. The metal was most likely bearing material, meaning the bearings are failing. This would require a differential to replace all the bearings and maybe even the ring and pinion gears while in there.

 

[miker104]

noise when letting off the gas plus metal in the rear diff is heavily weighed towards a bad differential (aka pumpkin). One board member sells rebuilt units for around $1000.

 

[IZwack]

Pretty sute its the pinion gear thas loose - which has been discussed quite a few times on the forum since its a pretty common problem with the Ford 8.8 axle. Anyway, one way to diagnose this is to disconnect the rear driveshaft again and pull/push on the rear axles yoke. If it moves up/down by any amount, its loose.

 

[wreckop]

Problem solved...thanks for the ideas

It was the carrier bearings in the differential. Replaced both and the noise is gone.

 

[Javadog123]

Thanks for posting the final fix. It is always very helpful for everyone.