# Help! Squeaking noise while driving and braking!



## rph74 (Dec 27, 2003)

I need help diagnosing this problem. I'm hoping it is just my brake pads, but the squeaking happens even at 75+mph. It sounds like it is coming from the front of the car. It happens when turning and going straight. Its a 98 540i automatic.

Thanks for your help!


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## norcal 528i (Dec 2, 2003)

I had a similar problem when I bought my car. Basically during braking and hard turning I would get a squeek that sounded like brakes or suspension from the front pass side. As it got worse it started to squeek while driving straight also. Dave Z suggested the brakes and I found an amazing amount of brake dust caked on the caliper. I used a wire brush to remove all the dust and hit it with brake clean, reinstalled everything with lots of anti-sieze and everything has been great about 9 months now. HTH


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## rph74 (Dec 27, 2003)

norcal 528i said:


> I had a similar problem when I bought my car. Basically during braking and hard turning I would get a squeek that sounded like brakes or suspension from the front pass side. As it got worse it started to squeek while driving straight also. Dave Z suggested the brakes and I found an amazing amount of brake dust caked on the caliper. I used a wire brush to remove all the dust and hit it with brake clean, reinstalled everything with lots of anti-sieze and everything has been great about 9 months now. HTH


Thanks for your reply. I hope that all it is is brake dust. It is a pretty loud squeak though. Did yours squeak when driving also and not just braking?


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## jvr826 (Apr 22, 2002)

rph74 said:


> Thanks for your reply. I hope that all it is is brake dust. It is a pretty loud squeak though. Did yours squeak when driving also and not just braking?


You may also have a pebble lodged between the brake shield and the rotor. It sounds much worse than it is. I've had this happen to me many times when I was parking in a dirt/gravel parking lot every day. For me, evantually it would fall out through driving the car. Hitting a few good bumps didn't hurt either.


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## BillP (Jan 4, 2002)

jvr530i said:


> You may also have a pebble lodged between the brake shield and the rotor. It sounds much worse than it is. I've had this happen to me many times when I was parking in a dirt/gravel parking lot every day. For me, evantually it would fall out through driving the car. Hitting a few good bumps didn't hurt either.


If this is the problem, try the following:

* Back up @10-15mph, hit the brakes
* Go forward @10-15mph, hit the brakes
* Repeat a few times

Bill


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## rph74 (Dec 27, 2003)

jvr530i said:


> You may also have a pebble lodged between the brake shield and the rotor. It sounds much worse than it is. I've had this happen to me many times when I was parking in a dirt/gravel parking lot every day. For me, evantually it would fall out through driving the car. Hitting a few good bumps didn't hurt either.


That is very possible here. We took a drive out to the country, and I drove on a gravel road.


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## rph74 (Dec 27, 2003)

I replaced the rear brake pads, and the squeak is gone now. I'm surprised the brake pad sensor did not go off.


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## DZeckhausen (Mar 11, 2003)

rph74 said:


> I replaced the rear brake pads, and the squeak is gone now. I'm surprised the brake pad sensor did not go off.


The brake sensor only goes off when that one pad gets down to less than 2mm of material remaining. The other three pads in the rear brakes are not monitored. I've seen several E39s that have worn a pad right down to the backing plate while the monitored pad still had enough life left to not trigger the sensor.

It's odd that BMW only monitors two out the eight pads for wear. While the first set of pads usually wear out at the same rate, the second and third sets often do not. That's due to a number of things, including gummed up caliper slide pins, excessive amounts of caked on brake dust in the caliper body, and sticking caliper pistons due to brake fluid change intervals being ignored.


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## rph74 (Dec 27, 2003)

DZeckhausen said:


> The brake sensor only goes off when that one pad gets down to less than 2mm of material remaining. The other three pads in the rear brakes are not monitored. I've seen several E39s that have worn a pad right down to the backing plate while the monitored pad still had enough life left to not trigger the sensor.
> 
> It's odd that BMW only monitors two out the eight pads for wear. While the first set of pads usually wear out at the same rate, the second and third sets often do not. That's due to a number of things, including gummed up caliper slide pins, excessive amounts of caked on brake dust in the caliper body, and sticking caliper pistons due to brake fluid change intervals being ignored.


Thanks for the insight on this. Lesson learned. You cannot depend on the brake pad sensor to know that it is time to change out the pads.


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