RX400h Wheel bearing advice (I think)

phb10186 · September 20, 2019

So, after the Cat replacement, I just today noticed a creaking from the rear of the car on turning left (and possibly also right)...

I got under the car and had a good poke about. First thought it may have been a missing exhaust hanger - possibly from the cat replacement job... but those are all there. Had a good old yank of everything under the car... doesn't seem to be anything obvious.

Jacked it up on both rear sides, and there is absolutely no play in either wheel bearing so it would seem.

Gave the coils and struts a good look, and those are looking fine too.

Noise is definitely from the rear, near side I think, and while turning left... Sounds like something is moving but it's not, I couldn't describe it as knocking or that slight graunch you get with failed bearings. On the straight its completely silent, at all speeds.

Only other thing I noticed (but have no reference to another 400), is that the near side rear drive shaft from the hybrid motor had a bit more play than the other side... if you give it a bit of muscle, there is some lateral movement between the centre and the shaft, but with 85k miles, I can't think that's anything other than expected.

I also took the spare out, and reassembled ensuring it was tight enough.

Does the RX 2 suffer with front or rear bearing failure typically? Have had a look at previous threads, but the symptoms are fairly broad. Its the lack of play that is intriguing

Any thoughts?

smitham · September 24, 2019

I do know that the old test of wheel bearing wear by looking for play or movement in the wheel doesn't seem to work on the RX400h. A couple of years ago, I was confused about a low rumbling noise from one rear wheel but it only occurred when driving above 30-40 mph and got worse with speed. The mechanic directed me towards the diff having concluded the bearings were good as there was no play at all. So I went to a diff specialist who had never worked on RXs before but luckily for my wallet, he went back to the bearing and used some kind of sound device (Mrs Smitham was present, not me!) and then concluded that in fact, it was a bearing. He changed this for a modest sum and the noise duly went away - which was a relief for me. But disappointment for the engineer as he wanted to work on the hybrid diff as he said his contact in Lexus had said that there never has been a diff failure reported in the UK!

So maybe, it is the bearing in your case - I would take it to a trusted gearbox and diff specialist rather than an ordinary mechanic.

Btw this trusted diff engineer saved me before many years ago when I had a 5 series beamer and one day, the steptronic gearbox wouldn't engage. I took it to an ex-BMW mechanic who said, "sorry, gearbox is gone, going to cost thousands". He also offered me 500 quid for the car. I was gutted but I decided to take it to the diff engineer and waited for his call with the estimate for thousands of pounds. I was so glad I did take it, since the call came, he announced that it was "fixed". "How much?" I asked. "£30!!" So it seems all the bolts linking the shaft to the diff had fallen out, so the wheels wouldn't turn and the diff just spun in space and needless to say I never used the BMW mechanic again!

phb10186 · September 24, 2019

That's really useful, thanks for that.

After I couldn't find any play in anything, I took the spare wheel out, cleaned everything and put it all back... first time I've done that since I bought it. Tightened the spare as far as it seemed to want to go, and I've not heard that knocking since... but that was only one short drive, trying to replicate it.

So, all i can assume is that the spare suddenly came slightly loose somehow... or its chance, or whatever... but for the moment it seems to have gone. I'll monitor this.

Noise could well have been just a small knocking of the spare wheel. Both rear bearings look original to me, though one of the rear calipers has been replaced I noted.