Rattle/knocking From Driver Side Dash Rx400H

[BGLister]

My RX400h is coming up to 2 years old and 20,000 miles now. It is booked in for the 20K service next week.

I have recently noticed an intermittant rattle/knocking when I have been driving, but it is difficult to say where it is coming from (these things usually are difficult) except to say it is coming from deep down under the dashboard on the driver side.

This rattle/knocking noise seems to happen when driving on a coarse road surface, driving over road markings, or a cat's eye for instance. Sometimes it happens on rougher terrain such as pot holes etc, but not necessarily. It is difficult to reproduce at will, but I hear it on every journey now. This is something that I have only recently come to notice, so wondered whether something has loosened with time.

I have checked under the dasboard in the footwell area and can feel various bundles of cables and pieces of trim. Where I can find something that has the potential to rattle or knock against something else, I have wrapped butyl tape around it (anti-rattle tape). No change in that the rattle/knocking sound still happens.

As good as Lexus technicians can be (no, not always), I am hesitant to let them start pulling the interior trim to pieces as they will no doubt get scuffed/scratched/stressed and various clips would have to pulled out and go back in, probably not getting replaced. The car is in mint condition, so don't want it getting spoilt - although the knocking is getting annoying.

The other possibility is that the sound is getting transmitted up via the suspension or chassis from under the car. It does not really sound that way, but know that these things can be deceiptful. Amongst the possibilities are things like the suspension, exhaust mounts, heat shield.

So would like to ask, has anyone here encountered a similar issue with their RX, found out what the problem was, and managed to get it solved?

With thanks

Bryan

[jashcroft]

Mine makes a similar noise. I took it back to the garage I bought it from (Mercedes Dealer) and one of their technicians went for a test drive with me. He thinks it's coming from up front on the drivers side somewhere. Its going in on Friday for a proper check and hopefully a solution.

[rhosneigr]

I have the same rattle on mine which seems to have started during the cold weather this last winter. I've been playing around with different tyre pressures as well since it seemed to coincide with the tyres being replaced but I can't be certain about that, but it's still there. Would be interested to know if the dealers find anything. Mine's not due for a service until Sept.

[BGLister]

Thanks chaps. I am not sure whether it is good news or bad news that you are both encountering the same. I too was wondering whether the cold weather was precipitating this. I did not notice it quite so much with the warmer weather yesterday, but saying that, its 11C outside this morning and the rattle came to haunt me.

These things are difficult to describe, but the noise seems to happen when the front end of the car is "bouncing" on its suspension, albeit it only has to be slight. I will try and take a look from underneath this weekend it it if dry.

If either of you find out more before I do, please let me know.

With thanks

Bryan

[rhosneigr]

I also get this rattle when the electric motors are labouring so to speak. i.e when the petrol engine shuts down and the electric motors take over after a sudden burst of acceleration. Hope you understand that, its very difficult to explain.

[BGLister]

That is interesting. Is that (as far as you can tell) the same rattle/knocking or another one? I will have to check out which mode the vehicle is operating in and see of that is the same. What kind of mileage are you on? Did you notice when it started to happen?

Thanks

Bryan

[jashcroft]

Just been to pick my car up, it turned out to be a loose bolt on a wishbone, which is what they told me. Just drove 10 miles back to my office and the noise has gone away.

[BGLister]

Thanks for the update and fingers crossed that has solved the problem for you. My car is 09 vintage with 20,000 miles - how does that compare to yours for the wear and tear stakes? I would hope that checking the suspension and occaisional bolt would be something covered on a service.

Thanks

Bryan

[jashcroft]

My car is 07 with 27,000 miles on the clock.

[rhosneigr]

My car is Sept 08 with 33K. The noise seemed to start when I had new tyres fitted all round in Sept last year(not 100% sure) that is why I've been experimenting with different tyre pressures. I will have a look at the bolts on the steering joints etc as soon as I can or I might take it to the dealership next week and mention what Jashcroft's dealership discovered.

[BGLister]

Thank you both for sharing the information. Although I am a little behind you both on the mileage, the roads here in West Yorkshire have been severely affected by the last two winters and have at times become very pot holed. I suppose the effect these can have upon suspension components and fixings could cause them to work loose. Likewise, I will take a look under the car over the weekend, other than that, I will ask the service technicians to make an inspection of the area. If that it was the problem is, at least it is easily solved.

Funny you should mention tyre pressures as I checked mine recently and they were low. After adding air, the rattling/knocking seem to be less frequent - but then again, it may have been a placebo affect!

[BGLister]

Car serviced, everything checked underneath (allegedly) - nothing reported back - but STILL rattles. May be a case of TADTS (they all do that Sir). I think it could be the undertray, which they say comes off for the service, but I will probably never know.

The 60 reg RX450h loan car rattled rather more than I expected from the back and the driver door. Rather disappointing as they have been making them around 2 years now. Pursuit of Perfection? Hmmm...

[Boxbrownie]

I suppose they checked the brake pads? I had a terrible ratling suddenly appear from the front wheel drivers side, every bump in the road sounded like something was hanging on by a thread and that something was a tin can with ball bearings inside!

Anyway turns out it was the anti rattle (makes sense!) clips on the outer brake pad had broken and fallen out, the pad still worked fine but it rattled.

Does the rattle disappear if you lightly apply the brakes? That was the give away for my problem.

[BGLister]

UPDATE.

Looks like the problem has been finally solved thanks to Lexus Manchester (RRG Group). It was a drop link on the anti-roll bar that had play in it. Not sure if the part was a little out of spec, or 20,000 miles wear and tear on West Yorkshire roads, but diagnosed and replaced under the warranty. First class service from the dealership.

Finally - rattle free driving again - and not a dashboard rattle after all!

[Roger Spears]

On 2/24/2011 at 4:43 AM, BGLister said:

My RX400h is coming up to 2 years old and 20,000 miles now. It is booked in for the 20K service next week.

I have recently noticed an intermittant rattle/knocking when I have been driving, but it is difficult to say where it is coming from (these things usually are difficult) except to say it is coming from deep down under the dashboard on the driver side.

This rattle/knocking noise seems to happen when driving on a coarse road surface, driving over road markings, or a cat's eye for instance. Sometimes it happens on rougher terrain such as pot holes etc, but not necessarily. It is difficult to reproduce at will, but I hear it on every journey now. This is something that I have only recently come to notice, so wondered whether something has loosened with time.

I have checked under the dasboard in the footwell area and can feel various bundles of cables and pieces of trim. Where I can find something that has the potential to rattle or knock against something else, I have wrapped butyl tape around it (anti-rattle tape). No change in that the rattle/knocking sound still happens.

As good as Lexus technicians can be (no, not always), I am hesitant to let them start pulling the interior trim to pieces as they will no doubt get scuffed/scratched/stressed and various clips would have to pulled out and go back in, probably not getting replaced. The car is in mint condition, so don't want it getting spoilt - although the knocking is getting annoying.

The other possibility is that the sound is getting transmitted up via the suspension or chassis from under the car. It does not really sound that way, but know that these things can be deceiptful. Amongst the possibilities are things like the suspension, exhaust mounts, heat shield.

So would like to ask, has anyone here encountered a similar issue with their RX, found out what the problem was, and managed to get it solved?

With thanks

Bryan

What was your issue? 

[Roger Spears]

On 2/24/2011 at 4:43 AM, BGLister said:

My RX400h is coming up to 2 years old and 20,000 miles now. It is booked in for the 20K service next week.

I have recently noticed an intermittant rattle/knocking when I have been driving, but it is difficult to say where it is coming from (these things usually are difficult) except to say it is coming from deep down under the dashboard on the driver side.

This rattle/knocking noise seems to happen when driving on a coarse road surface, driving over road markings, or a cat's eye for instance. Sometimes it happens on rougher terrain such as pot holes etc, but not necessarily. It is difficult to reproduce at will, but I hear it on every journey now. This is something that I have only recently come to notice, so wondered whether something has loosened with time.

I have checked under the dasboard in the footwell area and can feel various bundles of cables and pieces of trim. Where I can find something that has the potential to rattle or knock against something else, I have wrapped butyl tape around it (anti-rattle tape). No change in that the rattle/knocking sound still happens.

As good as Lexus technicians can be (no, not always), I am hesitant to let them start pulling the interior trim to pieces as they will no doubt get scuffed/scratched/stressed and various clips would have to pulled out and go back in, probably not getting replaced. The car is in mint condition, so don't want it getting spoilt - although the knocking is getting annoying.

The other possibility is that the sound is getting transmitted up via the suspension or chassis from under the car. It does not really sound that way, but know that these things can be deceiptful. Amongst the possibilities are things like the suspension, exhaust mounts, heat shield.

So would like to ask, has anyone here encountered a similar issue with their RX, found out what the problem was, and managed to get it solved?

With thanks

Bryan

What was your issue 

[Roger Spears]

On 2/24/2011 at 4:43 AM, BGLister said:

My RX400h is coming up to 2 years old and 20,000 miles now. It is booked in for the 20K service next week.

I have recently noticed an intermittant rattle/knocking when I have been driving, but it is difficult to say where it is coming from (these things usually are difficult) except to say it is coming from deep down under the dashboard on the driver side.

This rattle/knocking noise seems to happen when driving on a coarse road surface, driving over road markings, or a cat's eye for instance. Sometimes it happens on rougher terrain such as pot holes etc, but not necessarily. It is difficult to reproduce at will, but I hear it on every journey now. This is something that I have only recently come to notice, so wondered whether something has loosened with time.

I have checked under the dasboard in the footwell area and can feel various bundles of cables and pieces of trim. Where I can find something that has the potential to rattle or knock against something else, I have wrapped butyl tape around it (anti-rattle tape). No change in that the rattle/knocking sound still happens.

As good as Lexus technicians can be (no, not always), I am hesitant to let them start pulling the interior trim to pieces as they will no doubt get scuffed/scratched/stressed and various clips would have to pulled out and go back in, probably not getting replaced. The car is in mint condition, so don't want it getting spoilt - although the knocking is getting annoying.

The other possibility is that the sound is getting transmitted up via the suspension or chassis from under the car. It does not really sound that way, but know that these things can be deceiptful. Amongst the possibilities are things like the suspension, exhaust mounts, heat shield.

So would like to ask, has anyone here encountered a similar issue with their RX, found out what the problem was, and managed to get it solved?

With thanks

Bryan

Please let me know what your issue was. 

[Greisingel]

Thread over 12 years ago