Advice on RX450h ?brake noise? please?

[PSB10K]

Hi, 

I have a 2012 RX450h Premier and it has been into Lexus Croydon four times for service, new front discs/pads, MOT, etc.  Each time I've asked them to investigate annoying intermittent noises that appear to be under my feet.  Probably associated with the brakes, and worst first thing in the morning.  You can sometimes hear it just be pressing the brake pedal when stationery so it can't be anything to do with the discs and pads (which have been replaced).  On the first 3 occasions, Lexus just ignored it and made no comment either way.  This time, I got a bit more insistent and was told that "this is a common fault, and that Lexus are on the case trying to sort it".    

Do I believe them or are they just trying to fob me off?   In other words, has anyone else experienced this problem.  It sounds like a puppy yapping (if you know what I mean).

Any advice gratefully received.  If easier, my e mail address is peterblok@talktalk.net

Thanks - Peter 

[Herbie]

Can you record it and post it on here?

[Zotto]

Isn't the noise  the normal sound of brakes hydraulic circuit pressure "charging"?

[Herbie]

Just now, Zotto said:

Isn't the noise  the normal sound of brakes hydraulic circuit pressure "charging"?

That happens when the driver's door is opened and can't possibly be described as "a puppy yapping."

It's the "puppy yapping" that has me intrigued and why I asked for a recording because I've never heard anything like that coming from any car I've ever owned

[Barry14UK]

Does this happen even in park with start button still to be pressed?  Also does it happen if you depress pedal very slowly and part way? Does it become  more pronounced if you depress  the pedal more quickly and make the same sound again if you immediately depress pedal again?  I assume you have checked there is no debris caught up and any return spring is not rubbing on anything.

[PSB10K]

Thanks for your replies Guys,

It's obvious that this is not a common fault then!  This is my 4th RX, and it's a new one on me.     Right, answers: 

1.  Herbie - difficult to record as the noise is somewhat intermittent, but I'll have a go.  Nothing to do with the door being open, exactly the same with the door closed

2.  Zotto - it may well be the  'normal sound of brakes hydraulic circuit pressure  charging', but it's a new one on me, and why didn't my local Lexus garage tell me that?

3.  Barry - The start button has to be pressed for the noise to appear.  And repeated pressing hard on the brake pedal when in Park can reproduce it, but the noise is still there when reversing out of my garage without touching the brake.  Background is that I've owned the car for about 2 years, and the noise has always been there.

I have e mailed Lexus UK to ask if they have any comments or solutions.  I do believe I am being fobbed off by Lexus Croydon, especially as the vehicle is under a comprehensive warranty.

Curing it is not essential and it seems to have no effect on the smooth running of the car.   it's just an annoying noise that shouldn't be there, and may cause a problem when I eventually sell the car.

wbw - Peter 

[Barry14UK]

The fact that nobody else here has experienced this makes me feel that this is not a characteristic and Lexus need to find the fault and remedy it.  It may not affect the safety of the car but that has not been established as yet.  

I have never had a hybrid previously but those cars I had with power assisted brakes took up the slack on starting noticed by being able to more easily press the brake pedal initially.   It seems to me that this must be possible in electric mode as this may be the way a car may be driven sometimes without the engine being engaged.  So although you didn't touch the brake on reversing out of your garage, you did previously have to press the brake pedal  in order to activate the ready button.  So doing this likely moved the pads slightly.  I just wonder whether a back plate is distorted and as the pads are moving a little a noise is produced, more readily when reversing than when going forward which only results in a noise when the pedal is depressed.

With the car jacked up and front wheels removed, Lexus should be able to find the answer.  Do let us know what transpires. 

[Moshchops]

I am experiencing this sound and the reference of a puppy sound is apt.

No loss of brake fluid or system being faulty and the noise isn't consistent or loud .

It is however noticeable.

Recently fitted after market pads to the rear.

Car being the same rx450 h but sport not premier

 

[ColinBarber]

3 hours ago, Moshchops said:

I am experiencing this sound and the reference of a puppy sound is apt.

 

Please record and post here if possible. The OP hasn't been on the site since reporting this issue so we don't know if it ever got resolved.

[Zotto]

Brake  pedal spring noise?

[Moshchops]

No...although that too is noticeable.

I may bleed rear calipers, its the only thing I can think of.

Recently mot'd after I fitted pads on rear.

I know they are working efficiently,  it's just an annoying sound....like that made by a puppy

 

[ColinBarber]

I suspect it is air in the master cylinder / accumulator. You cannot fully bleed the system without techsteam as you need to put the system in a special mode and do a 'zero down' the accumulator to push all the fluid into the reservoir.

CAUTION:

The intelligent tester must be used for air bleeding. If not used, the air bleeding will be incomplete, which is hazardous and may lead to an accident.

[PSB10K]

On 10/27/2022 at 4:26 PM, Moshchops said:

No...although that too is noticeable.

I may bleed rear calipers, its the only thing I can think of.

Recently mot'd after I fitted pads on rear.

I know they are working efficiently,  it's just an annoying sound....like that made by a puppy

 

Hi Guys, 

Sorry - I should have reported back two years ago . . . .

I eventually persuaded Lexus to fix the problem under warranty (which I had purchased from them), and it turned out that I needed a new Brake Attenuator Unit fitted, a job which would have cost well over £1000 (I'm told).

So, had I had to have paid for it myself, I would have stuck with the puppy noises.  Not the end of the world, just annoying!

Hope this helps

Peter