Hiss Sound When Pushing The Brake Pedal

[zhwwu]

Hi, I just got a new 2007 GX 470 and on my way driving back from dealership I notice a slight hiss sound inside the vehicle(like air evacuating through a small hole) when braking. If you know anything about it, please pass it along.

Thanks in advance!

[denslexusgx470]

zhwwu

congrats on the purchase of a new GX and welcome to LOC!

Answer to your question is, it's a normal thing. I'm not quite sure why the brakes do that but it is perfectly normal. Even my 4Runner has that hiss sound when braking so it's perfectly normal and enjoy your beautiful new Lexus.

[schan1w]

Is it a humming sound like a motor is running after you press the brake pedal a few times? You can also feel a vibration in the brake pedal during this time. If so, this is the brake booster running to repressurize the system. My 07 GX makes this sound/vibration and it annoys me. I've gotten use to it, but I think it's worse on my GX than others. Went to two different dealers, and both claim it's normal. 4Runner has the same brake system, so they have this "feature" too.

[denslexusgx470]

Is it a humming sound like a motor is running after you press the brake pedal a few times? You can also feel a vibration in the brake pedal during this time. If so, this is the brake booster running to repressurize the system. My 07 GX makes this sound/vibration and it annoys me. I've gotten use to it, but I think it's worse on my GX than others. Went to two different dealers, and both claim it's normal. 4Runner has the same brake system, so they have this "feature" too.

hmm never quite heard of this problem before.. He dd mentioned that it sounds like a hiss, like air leaking thru a small hole so more than likely it's just the pedal when you apply pressure to it.. It's normal, what is it I really don't know but don't worry about it. ;)

[zhwwu]

Is it a humming sound like a motor is running after you press the brake pedal a few times? You can also feel a vibration in the brake pedal during this time. If so, this is the brake booster running to repressurize the system. My 07 GX makes this sound/vibration and it annoys me. I've gotten use to it, but I think it's worse on my GX than others. Went to two different dealers, and both claim it's normal. 4Runner has the same brake system, so they have this "feature" too.

hmm never quite heard of this problem before.. He dd mentioned that it sounds like a hiss, like air leaking thru a small hole so more than likely it's just the pedal when you apply pressure to it.. It's normal, what is it I really don't know but don't worry about it. ;)

Thanks for all the replies. I did take the car to the service department of the dealership yesterday and let the service manager drive to replicate the sound, he claimed it is totally normal (I don't remember the exact reason he gave) and every vehicle does that. It is just so quiet inside Lexus that is why the hiss sound kind of pop out.

[denslexusgx470]

Just don't sweat it and enjoy the vehicle! Heck if I worried about that sound when I got my GX, I'd have to pull my hair out worrying about my 4Runner that has the SAME hiss sound when you press on the brakes! ;)

[lburn]

Hi,

I have a 2007 GX470 and have the same problem with my brakes. I also brought it into the dealer to see if they can fix, but was told it is normal. I was hoping that they could fix the problem, because it is really annoying. It may be just me but I think that a vehicle at this price should not have any strange noises, functional or not. Buy the way, previous to buying this GX I bought a new ES, and took it back after 1500 miles because of transmission problems. The dealer also told me that the skipping transmssion was normal. I didn't buy that, and they gave me a full refund after writing Lexus with my experience. I really like the dealer, so I purchased this new GX. Overall I have never had any problems with Lexus cars as I had a 2004 GX with no noises at all. I guess I am just a stickler when it comes to getting what I pay for. Hey Lexus touts it's pursuit of perfection with these cars, why should we the buyer, expect anything less?

[schan1w]

Hi lburn - which problem? hissing or vibration?

[denslexusgx470]

Hi,

I have a 2007 GX470 and have the same problem with my brakes. I also brought it into the dealer to see if they can fix, but was told it is normal. I was hoping that they could fix the problem, because it is really annoying. It may be just me but I think that a vehicle at this price should not have any strange noises, functional or not. Buy the way, previous to buying this GX I bought a new ES, and took it back after 1500 miles because of transmission problems. The dealer also told me that the skipping transmssion was normal. I didn't buy that, and they gave me a full refund after writing Lexus with my experience. I really like the dealer, so I purchased this new GX. Overall I have never had any problems with Lexus cars as I had a 2004 GX with no noises at all. I guess I am just a stickler when it comes to getting what I pay for. Hey Lexus touts it's pursuit of perfection with these cars, why should we the buyer, expect anything less?

So are you telling us that you previously had a 2004 GX470 that DIDNT have this hissing noise from the brakes, and now you have purchased a 07 GX that HAS the hissing sound? To my knowledge, I believe ALL GX470s have the hissing sound when pressing on the brakes. Heck, even the 4Runners have the hissing sound even on the V6s which have a different engine than the GX. ;)

[lburn]

Hi,

I have a 2007 GX470 and have the same problem with my brakes. I also brought it into the dealer to see if they can fix, but was told it is normal. I was hoping that they could fix the problem, because it is really annoying. It may be just me but I think that a vehicle at this price should not have any strange noises, functional or not. Buy the way, previous to buying this GX I bought a new ES, and took it back after 1500 miles because of transmission problems. The dealer also told me that the skipping transmssion was normal. I didn't buy that, and they gave me a full refund after writing Lexus with my experience. I really like the dealer, so I purchased this new GX. Overall I have never had any problems with Lexus cars as I had a 2004 GX with no noises at all. I guess I am just a stickler when it comes to getting what I pay for. Hey Lexus touts it's pursuit of perfection with these cars, why should we the buyer, expect anything less?

So are you telling us that you previously had a 2004 GX470 that DIDNT have this hissing noise from the brakes, and now you have purchased a 07 GX that HAS the hissing sound? To my knowledge, I believe ALL GX470s have the hissing sound when pressing on the brakes. Heck, even the 4Runners have the hissing sound even on the V6s which have a different engine than the GX. ;)

I am absolutely telling you that my 2004 GX did not have that problem. Since Lexus makes such quiet cars sounds are quite noticeable. I can honestly say that this is a new noise that I have never encountered before. I cannot speak for 4Runners because I have never owned one, I am merely giving my experience with cars I have owned and driven.

[lburn]

Hi lburn - which problem? hissing or vibration?

It is a definate hissing noise, like air being released every time you press on the brakes.

[denslexusgx470]

Well I havent heard a GX W/O the hissing sound from the brakes, but let's just consider your 04 a "special" GX. ;) Cuz all the GX's I've been in ALL have the hissing sound, and even the 4Runners as I have mentioned numerous times in the past so it is absolutely NORMAL, trust me. It's better for the hissing sound to be the "normal" thing rather than have the dealer tell you to your face that the CLUNK is a normal thing! I've experienced that before, and DEFINITELY the clunk isn't normal. ;)

[The G Man]

I guess everybody hear diff. things, because I have never heard any hissing sound from the brakes.

[lburn]

Well I havent heard a GX W/O the hissing sound from the brakes, but let's just consider your 04 a "special" GX. ;) Cuz all the GX's I've been in ALL have the hissing sound, and even the 4Runners as I have mentioned numerous times in the past so it is absolutely NORMAL, trust me. It's better for the hissing sound to be the "normal" thing rather than have the dealer tell you to your face that the CLUNK is a normal thing! I've experienced that before, and DEFINITELY the clunk isn't normal. ;)

Well, could it be possible that there are actually other Lexus owners that have had problems/or not have problems that you personally have not experienced? Being a "Guru member" and moderator of this board perhaps your opinion should not be considered by others the end all be all. And since I have had owned twice as many GX's than you have should one say I have more experience on this subject? As far as your 4-Runner, who really cares. Maybe you should go be a "guru" on their board. :chairshot:

[nc211]

He is.....

And he's just trying to tell you that IT IS NORMAL!!!! My 05' 4Runner does it too! And the 06 GX I was in three days ago did it as well.

Guru members like Dens, know these cars from top to bottom, front to back, inside and out. Who cares how many you've owned. It only takes ONE to learn the car and the mechanics of it. Maybe they updated the braking system in 05' to reduce warping rotors, which is why your 04' didn't make that noise?

[Reboot]

Wow, no reason to bite off the guy's head. He's just telling you that they all do that. I have a 2004 GX and I hear the hiss everytime. It's the brake cylinders doing their work.

Is it noticable? Yes.

Is it annoying? No.

Do I still love my truck? You bet!

Enjoy the truck, there's nothing wrong. Put the windows down, turn on the radio and enjoy the ride.

[denslexusgx470]

Well, could it be possible that there are actually other Lexus owners that have had problems/or not have problems that you personally have not experienced? Being a "Guru member" and moderator of this board perhaps your opinion should not be considered by others the end all be all. And since I have had owned twice as many GX's than you have should one say I have more experience on this subject? As far as your 4-Runner, who really cares. Maybe you should go be a "guru" on their board.:chairshot:

Whoa easy there buddy... Now we wouldnt want this topic to be closed now do we?? Anyways, MAYBE there are a few GX470s out there that dont have the hissing brake sound. Ok it's possible so let's keep an open mind. That's why, if you didnt notice my one sentence "but let's just consider your 04 a "special" GX." means that I'm not saying that you are incorrect and I'm always right. I'm saying maybe there are GX's out there that DONT have the hissing sound.. Back then, a lot of people had a sulfur smell problem, but I never encountered that.. So it's just plain ol luck, because nothing is perfect, cuz remember "Pursuit of Perfection" ;)

Besides, I have not only driven my GX, but a few other GX470s also, but as NC said, it only takes ONE to know the in's and out's of a certain vehicle... I already knew about this GX470 7 months before it was launched in Dec 02 and I'm familiar with the other 2 generations of this GX470 ( yes our GX is the 3rd Gen Toyota Land Cruiser Prado) so I know quite a bit about this vehicle. ;)

[mcmann]

Is it possible that there is another GX 470 that doesn't hiss when you break? - I've had my 2007 for 6 months and it doesn't hiss. I've even asked other members of the family to listen for it when they drive my car but so far no one has heard it. My car does exhibit another annoying trick - every now and then when stopped, with my foot on the brake, I feel what can best be described as a 'bump' almost like a little tap from another car. My previous LX 470 didn't do it. Anoyone else have this problem?

[The G Man]

You have the clunk, check out this thread.

http://us.lexusownersclub.com/forums/index...showtopic=29288