Rear diff strange moan noise

[Gillinski]

Hello,
Since a few months i have a strange noise coming from the rear diff. The noise is there in low speed, no mater if i accelerate or not. It sounds like a bearing moan. I thought it was the rear wheel bearings. I replaced them and the noise is still there. Lo leaks, no play on the drive shaft. Could it be the pinion bearing?

 

[Pighead]

I might check my u-joints before i dug into the diff...

 

[whitey45]

Pull the driveshaft and check the pinion preload. There should be no play, common for the pinion nut to back off if not properly set up..

 

[Gillinski]

U-Joints and pinion nut checked. Absolutely no play.

 

[Gillinski]

Hi, I removed the rear driveshaft and drove in 4H. No moaning noise! So it could be the U-Joints moaning? I thought U-joints tipical noise was clunk or click . I think i order 2 U Joints and give it a try before i open the axle, what do you think?

 

[70fj40]

Replacing U joints is never a bad idea on an FJ40 unless you know they have been recently replaced.

 

[jim land]

Don't buy generic joint, get some quality made in japan u-joint from cruiser Outfitters

 

[ToyotaMatt]

 

[Gillinski]

Don't buy generic joint, get some quality made in japan u-joint from cruiser Outfitters

I found 2 Oem Joints.
Thanks.
Gilles

 

[Gillinski]

New joints, still noise but now i found the culprit. The outer pinion bearing.

I got the race out too

I looked through the hole at the inside and the inner bearing looks good.
I'll replace that outer bearing and the oil seal and should be good.

 

[Gillinski]

Hi, do i have to put grease on that new bearing?

 

[pb4ugo]

No grease.

 

[Gillinski]

Ok it's done. Bearing replaced, nut torqued to specs, fresh oil filled , test drive. The noise is gone! Thanks for your precious help!
Gilles