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-   -   2011 GC - Crunching Noise Under Hood When Braking (http://www.jeepgarage.org/f107/2011-gc-crunching-noise-under-hood-when-braking-16067.html)

DJWeaver 12-09-2010 01:17 AM

2011 GC - Crunching Noise Under Hood When Braking
 
This crunching noise occurs when heavier than normal braking occurs where the vehicle has a slight forward pitch to the body during braking. Does not happen under normal braking.

Took it into dealer and they said they can't replicate the problem. Yet I can every day. Problem started when vehicle was 2 weeks old.

Any thoughts on cause? FYI - I doubt it is rusty routers or I think I'd get this with both light and heavy braking situations.

Marlin 12-09-2010 01:58 AM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
Do you feel a slight high speed pulse through the brake pedal?

Cperez 12-09-2010 08:09 AM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
Quote:

Originally Posted by DJWeaver (Post 314418)
This crunching noise occurs when heavier than normal braking occurs where the vehicle has a slight forward pitch to the body during braking.

That's exactly the way I've always described the sound of a properly functioning ABS system at work.

JoeSchmoe007 12-09-2010 09:37 AM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
In my old ZJ I had ABS engaging when it shouldn't have. Vehicle would be almost stopped already (less that 10 mph, normal braking conditions, dry road) and then ABS would engage, release the brakes and car would move 1-2 feet forward. It was really scary. Turned out ABS sensor on one wheel was going bad and at low speed was showing speed 2 miles different from other 3 wheels. Replacing faulty ABS sensor fixed it.

Bmwister 12-09-2010 04:29 PM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
It sounds like it might be some normal brake scrub vibrations for pads not yet perfectly mated to the rotor surfaces. If you brake firmly and not let up (i.e. come to a complete stop), do you still get that noise before you release your braking pressure? Brakes need some proper break-in time too and sometimes the rotor faces are sensitive to braking pressures which create small vibrations we can hear as a creak; I have also heard people describe it as a squawk or a "crunch" as you did. My WK2 did this on occasion during the first 1000 miles when I was not braking to a complete stop or braking lightly at very low, crawling, almost-stopped speeds. It doesn't do it anymore.

Do a few runs that require some firm barking that takes you 2 to 3 secs or so to come to a complete stop and try not to ride the brakes lightly. Don't slam on the brakes like in a panic stop; just apply a firmer pressure than you normally would. See if the noise goes away after you do this a few times. I had an Audi that made the same noise throughout its life whenever it was cold (stopped on a dime though).

DJWeaver 12-10-2010 01:40 AM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
Quote:

Originally Posted by Marlin (Post 314430)
Do you feel a slight high speed pulse through the brake pedal?

Hi Marlin,

Nope it's not an ABS kind of sound. There is no pulsing. Its a loud single occurance of a crunch on heavier then normal braking.

DJWeaver 12-10-2010 02:01 AM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
Quote:

Originally Posted by Bmwister (Post 314756)
Do a few runs that require some firm barking that takes you 2 to 3 secs or so to come to a complete stop and try not to ride the brakes lightly. Don't slam on the brakes like in a panic stop; just apply a firmer pressure than you normally would. See if the noise goes away after you do this a few times. I had an Audi that made the same noise throughout its life whenever it was cold (stopped on a dime though).

Thanks Bmwister. I'll try this. But the sound seems to be coming from axle area under the hood and not from the wheels themselves. But I'll give the a try just to confirm.

Cherodude 12-10-2010 07:27 PM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
DJWeaver: Have you checked out this thread about front end noises that may be similar? Maybe you should compare notes.

http://jeepgarage.org/showthread.php?t=16107

Marlin 12-12-2010 06:53 PM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
Quote:

Originally Posted by DJWeaver (Post 315123)
Hi Marlin,

Nope it's not an ABS kind of sound. There is no pulsing. Its a loud single occurance of a crunch on heavier then normal braking.

Ahhhhh ok.
Hmmm, sounding more like a bush of sorts.
Any luck yet?

sined240 12-12-2010 07:28 PM

Re: 2011 GC - Crunching Noise Under Hood When Braking
 
maybe the subframe shifting from not having the big subframe bolts tightened to spec at the factory? was a problem with the B6 Passats...


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