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Discussion Starter · #1 ·
Hi all ,

I have a encountered a problem recently with my GLC 300 which was purchased new in 2020.
A problem developed that when releasing the brake pedal, a hissing noise comes from the brake pedal - similar to a vacuum leak sort of. The noise is very annoying.
I have taken the car to a Mercedes service centre back in November last year; they checked and said nothing is wrong with the car. I was bit annoyed as clearly something is not right either. This service centre is not my usual dealer; I had to go there, as no appointments were available at my usual Mercedes dealer.
Has anyone experienced this? Car is still under warranty; I am planning to take to mu usual dealer next week along with the service.
Searching the web, I can see few posts regarding this.

Any details on this is much appreciated!
 

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GLC300e AMG Line Premium Plus in Spectral Blue
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Hi, I've just collected a 2021 GLC300e hybrid, and I've noticed a noise sometimes when I transfer my foot to the accelerator pedal? Didn't have it on my last GLC. Is yours definitely coming from the brake pedal? Jamie
 

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Hi all ,

I have a encountered a problem recently with my GLC 300 which was purchased new in 2020.
A problem developed that when releasing the brake pedal, a hissing noise comes from the brake pedal - similar to a vacuum leak sort of. The noise is very annoying.
I have taken the car to a Mercedes service centre back in November last year; they checked and said nothing is wrong with the car. I was bit annoyed as clearly something is not right either. This service centre is not my usual dealer; I had to go there, as no appointments were available at my usual Mercedes dealer.
Has anyone experienced this? Car is still under warranty; I am planning to take to mu usual dealer next week along with the service.
Searching the web, I can see few posts regarding this.

Any details on this is much appreciated!
Have the same issue GLC 300 2018. It happens after about 15 mins of driving and only when warm/above 70 F outside.
Went to dealer twice, they didn't find anything wrong.
 

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Happens to me twice a year. During cold temps here in Alberta, i noticed this and was like wtf the first year but it quickly became clear that it didnt happen in warmer weather. Just my experience in winter.
 

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Discussion Starter · #6 ·
Yes spot on... it comes after 15 mins of driving and hissing sound gets intensified more you drive from there...

i have come across that some say it’s air leak from break booster...
I took the car once to the dealer and they checked and say nothing wrong...but I believe something not correct
 

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Discussion Starter · #8 ·
my car is still under warranty and if something is wrong with the break booster, a probably a costly repair..... i want to get it done now before the warranty expires.
but I am not happy with the tratemnet of the Merc dealers, i have taken my car today for annual service, and want them to have a look again on this issue.
 

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Discussion Starter · #10 ·
Yes it comes definitely from the brake pedal and when the pedal is released...... generally noise comes after 15 mins of driving and hissing sound gets intensified more you drive from there...

There are few posts on the web...regarding this...
I also recently felt a sudden loss of power when accelerating from stand still, looking at some blogs on the web both these problems are interconnected.

i have come across that some say it’s air leak from break booster...
I took the car once to the dealer today…. Will see what they say.
 
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