Wiener

OK, so that took them over 3 hours yesterday. They did replace the actuator and now it's silent. It did cost Toyota over $3k. The service advisor told me that this happens when there is an air bubble trapped in the system. So my initial impression that it happened right after the first service visit was right. It was ok from the factory, they ****ed it up and than had to repair it. I just don't understand why does Toyota Motor Poland pay for it. The incompetent stealership should pay it.

Again: everything the dealership touches turns into ****. Not the first time unfortunately. It's a shame that Toyota/Lexus does not audit them more.

golferjack

Your dealer my be correct that it is an air bubble. I have a unique situation in that air in the actuator may be the culprit because I have the squawk, but only at high altitude, where air pressure may have an impact. I have a home in Denver, at 5000 feet and one in the mountains at 9000 feet. When I am in Denver, it never squawks, but when I go to my other home, it will on occasion squawk for a day or two and never do it again until I repeat the cycle and go back to Denver and then return to higher altitude, where it will again squawk. Sometimes it will squawk after I turn off the car, where the normal sound is some sort of buzzing, where I think the actuator is relieving its pressure reserve. The same buzzing sound occurs on our Rav hybrid when I open the door to use the car, where it is getting the vehicle ready for use and charging the actuator. The Rav does not squawk. I will probably never be able to get this fixed, because unless it starts squawking at lower altitude, the dealer will never hear it, and I know they will not do the TSB if they can’t hear the squawk.

Wiener

They may be correct, but it did not happen even once before the first service visit. I am sorry for you, your problem is even worse because not reproducible at normal altitudes. You may do as I did: create thorough video documentation and let them deal with it. Place a smartphone on the actuator, start accelerometer, reproduce and video-record. And make sure that it is the actuator: maybe it is something else in your case.

I have got no TSB for myself, only the information that they did replace the actuator. But there is a TSB for you: https://static.nhtsa.gov/odi/tsbs/20...54784-9999.pdf My dealer didn't even want to look at it as US TSBs do not apply in Europe. OK...

Wiener

OK... so yesterday while depressing the brake and switching from drive to reverse it returned and I have heard it twice. It does not occur as often as before (I can't reproduce it anymore), but still.

What am I supposed to do? The dealership has no idea on why it occurs. The american TSB also mentions that it is necessary to upgrade the reservoir to the newer version which they did not. But again, my RX450h is made in 2020 so maybe already with the upgraded reservoir on board.

I don't get it. How did Toyota manage to design such an issue? I have googled for this and no other brand has got that issue. And the braking system is not something extremely sophisticated.

I have found that the 2007 LS also did exhibit this behavior. L-SB-0178-09

Has anyone solved the problem yet? How?

andye39s

Are you talking about the the noise that sounds like a seal barking? My 08/2019 built RXh started doing it at around 2000 miles IIRC. It only happened right as the car came to a full stop, and only did it once in a while. I can't recall exactly when, my guess is around 5000 miles on the car, the noise is completely gone.

Wiener

Well... it kinda sounds like a seal bark if you sit inside but it is a rather short seal bark. Yes, it mostly happens after a full stop (like a second after full stop) but while braking firmly also did happen in movement. You can also feel the bark on the pedal.
You can hear the noise isolated in 0:21-0:23 for example.
https://streamable.com/r5fu27

golferjack

Mine is not related to movement. If the car has been sitting all night it will bark when I step on the brake to start the car. It then barks everytime I step on the brake. 'But then at some point it gets tired of barking and is normal until I return from low altitude and then the thing starts barking for a few days and then stops again.

Wiener

Well yes, it also barks at stop when parked. While shifting from P to R after night and then while shifting from R to D. I mean... maybe we are too **** about it? Although... my 18yo Audi A4 was a piece of junk but the brakes never barked at me. If my actuator has been replaced with a completely new one, it is not very probable that I have got two broken (factory and replacement one) actuators. So either it is a design flaw and every single RX450h should do this or... or it is not the actuator's fault. Does every single RX450h bark? Can we find at least one that does not? If we can't, this means there is a design flaw and Lexus has to redesign it, simple. But if we can find an RX450h that does not bark at all and never did, it means that something is different in our particular cars than in other RX450, which means that something is broken and needs replacement.

andye39s

I didn't hear the barking sound in your video. Just heard the normal whirring and clicking which is normal. The seal barking sound I used to get was kind of like a screech, very brief and only happened very occasionally right when the car comes to a complete stop. Never when the car was stationary. Again, it started at around 2000 miles on my car, and hasn't happened again since around 5000 miles. I now have 8000 miles on the car.

Wiener

I mean the sound you can hear between 0:21 and 0:23. It is like a bark/clunk. You can hear it inside and as you can see you can see that the accelerometer vibrates while it occurs.

andye39s

I just listened to it over and over a few times. I did not hear the seal barking sound that I heard in my car. You were stationary when pumping the brake pedal. I've never heard the seal barking noise in my car while stationary.

FWIW, all the sounds I heard from your video seem normal to me on a Lexus hybrid. I've owned every generation of RX. All were hybrids (except of course the 2001, no hybrid yet back then), 2006 RX400h, 2012 RX450h, and my current 2019 RX450h. Plus a CT200h in between. All of them made the noises in your video. I think every 3-4 presses of the brake pedal starts the whirring sound. If I'm not mistaken it is the system pressurizing so that you still have power brakes without the engine running. If you try to pump the brake pedal a few times on a regular gas car without the engine running, you will no longer have power brakes. Are you sure the clunking is not from you pumping the brake pedal? Without a gas engine drowning out all the sounds, you will hear everything in the hybrid while the engine is not running, especially when you have the phone resting directly on the brake module, amplifying every sound in the recording.

Wiener

No, the whirring/buzzing is fine. It has always done that sound and also my rav4 hybrid has done that.
I am absolutely sure that the clunking 0:21-0:23 is not from me pumping the brake pedal. I depress it, hold it depressed and without moving my foot or the pedal or anything it clunks all by itself. During the clunk the actuator shakes. And moreover... I not only hear it, but also feel it with my foot on the pedal. It happens always while depressing the brakes. Mostly while switching between P, D, R or at red lights - that is when you normally depress your brakes for a longer period of time. But has already happened in motion while having to brake hard.

Please bear in mind that the phone placed on the actuator did not record anything. I just started accelerometer app there to measure vibrations. Video and audio was recorded by another phone. And the clunk is quite loud, you can easily hear it both from outside and inside of the car.

I have called the dealership today and they will report the issue to the importer. They have had such issues with many NX but it's apparently first time it was not resolved by the actuator replacement. I will keep you updated.

Wiener

Status update: the importer has probably contacted Toyota Motor Europe. If you analyze the problem with common sense... the lines, which connect the actuator are actually above the brake fluid reservoir level. So... why should they keep air-free? So the air bubble theory may seem legit. Normally you would expect the air to go to the highest point of the system and that would be the actuator lines. Maybe this is as simple as that and the solution would be to lift the reservoir?

Wiener

Status update: I know how to solve the problem... temporarily for a day or two or like 50km. So, you have to provoke the ABS so that the actuator's valves open. Actuator is actually a pressure releaser for the brake lines. It is easiest to do on snow, ice or mud. Just find slippery surface, drive 40km/h and slam on the brakes until a complete stop. There, now the knock will not appear for some time. Not even once.

There can be some air bubble that gets pushed away from its natural position when ABS valves open and is quiet, but returns after some time to its natural position and makes the noise.

P.S. Don't crash, please.

golferjack

I don't know if you are correct about the air, but the theory might help explain why I get the noise when I go from high to low altitude. Interesting theory. At high altitude I press the brake peddle hard at at stop about 5 times and then after a few days, the knock goes away until I go to low altitude and the process starts all over again.