So a few days ago, I was in the passenger seat at night with the wife driving when I was jolted awake by a loud sound coming from the right rear passenger side. It sounded just like when one drives over those grates they put on the road to stop cattle from crossing. It lasted just 3 seconds and I asked my wife if she had seen any motorcycle chain or something like that on the road. Nope. Well, car felt and sounded fine after that.

Day before yesterday, I was driving in broad daylight (and I'm the kind who avoids even manhole covers if I can) and I heard the very same sound! Nothing on the road for sure. Still...car was fine and didn't feel any different. No more rumblings, whining or groanings.

Yesterday morning, just idling in traffic and going a slow uphill, the car let out this almight THUNK from the right rear passenger side. This time, it I actually felt the car jerk, like something had held it back and then let go all of a sudden.

I drove straight to my mechanic and after removing the wheels, decided that it was the wheel bearings at fault. Ordered the kit and then spent the rest of the day trying to get the thing back together again. He called everyone he knew, nobody had that bloody tool. The Snap on guy came, the Mac tools girl came...no go. In the end, after searching the whole shop for something suitable, we headed off to the local Rona's and bought a large pipe end. With some creative welding, we had a frankenstein tool that worked perfectly!

All in, a most instructive day for me. With the right tool, I believe I can do it myself now, with my buddy looking over my shoulder that is . ON the plus side, whilst figuring out how to remove the bloody hub, we removed the E-Brake, later finding that we didn't need to. I successfully put it back on myself, so I will fixing my e-brake next.

I'm not convinced the wheel bearing could make that sound and have that 'holding back' effect that I experienced, but if you look at the wheel bearing anyway, it looked and turned like it was shot. The seal was rusted through and one could see bits of hardened something in the races. So it was probably a good thing to replace anyway. Things is, after removal, the old bearings looked ok to my eyes. We checked out the flex disk, put in some fluid in the differential (it was just a tad low, but that could be cos the car was up on jackstands) and turned the tyres ad nauseum.

Still...I thought I heard another sound.... Only time will tell I guess.

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1987 300TD
1984 300D
755,000 KM and going strong
BC Canada

well, at least you have new bearings.

one other thing could be the half shaft.

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1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.

that's a strange one - but bearings do make sense - even if that was not the cause of your sound - it saved you from a problem later if the seal was shot.

Did you notice any tears in the CV boots on either half shaft?

the only other thing I can think of would be the driveshaft mid ship bearing - but that wouldn't sound like it was coming from a back wheel - as it's nearly in the center of the car...

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95 E300 Diesel 265k and counting

Well, all the boots looked cracked-like, but they were not cracked through all the way, if you know what I mean...like wrinkled.

We did try moving the shafts around, and they did have a little bit of play, which I think is normal no? And turning the wheels around didn't produce any other weird noises. So really...I can't think of anything else.

I really hope its not the diff...I mean, all I can think of is that it explodes on me whilst I'm at high speed. That's scary!

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1987 300TD
1984 300D
755,000 KM and going strong
BC Canada

if the problem was in your differential - at least in my experience - the noise would be more of a constant howling sound coming from the middle rear of the car - and it will change pitch / frequency when transitioning from accelerating to decelerating. Generally a diff noise is more of a "whine" or a "growl" not too much different than a typical wheel bearing noise - unlike your noise which was intermittent.

If you're genuinely concerned about the condition of the diff - now that you know your fill plug comes out OK - you might want to drain the diff and look for metal particles.

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95 E300 Diesel 265k and counting