My brakes make a weird noise. What's the deal?

August 9, 2009 1:44 PM

[Autofilter] My brakes make a grinding sound when I first start driving. After I use the brakes several times, usually after 5-10 minutes of driving (sometimes more), they're back to normal. In addition to the grinding sound, it's much harder to push down on the brake- this also disappears after using my brakes enough. What's up?

Almost two months ago, I had my brakes serviced and looked at. I got new brake pads, replaced (some, not all) rotors, etc. I got all the work they recommended done. My brakes were better than ever, until this problem started (probably two weeks ago). Once my brakes stop grinding, they are just as good as when I first got the work done. I have no idea if that has anything to do with it.

I'm of course going to have my car looked at, (I'm sure I'm killing my car or something) but I want to know what to expect. I was guessing something regarding my brake fluid being the issue, but I know nothing about cars so that's probably stupid.

The car is a 2000 Mercury Sable with about 78,000 on it.

posted by spaltavian to travel & transportation (17 comments total)

Is your driveway gravel?
posted by odinsdream at 2:00 PM on August 9

All brake rotors will develop some slight surface corrosion when the car sits, especially overnight. If normal function is restored after the first couple actuations of the brakes, everything is fine.
You could have a caliper that's hanging up from a poorly lubricated slide pin and it needs a little coaxing to free it after the car sits.
A problem with the brake fluid almost always results in a squishy, spongy pedal and increased braking distance.
There's no red BRAKE or yellow ABS light on, right?

You say it feels hard to push the pedal initially. Is the stopping distance increased too? Or is the pedal really firm but the brakes remain responsive?
posted by Jon-o at 2:00 PM on August 9

Nope. My driveway is paved, or I park on an asphalt street.
posted by spaltavian at 2:01 PM on August 9

are you the sort of person that washes your car frequently?
posted by Jon_Evil at 2:02 PM on August 9

Sorry, I should have said: yes, the ABS light is on the red BRAKE light is not on. (The ABS light was intermittent at first, but now is always on.) I'm honestly having a hard time telling if braking distance is increased. I have to press much harder to get the braking I want, but it seems that this could be because it's just much harder to push at first. However, I would say that, yes, braking distances are longer until the grinding stops.
posted by spaltavian at 2:06 PM on August 9

Do you feel the grinding or vibration in the pedal or is just audible?
posted by Jon-o at 2:11 PM on August 9

Yeah, I feel the grinding in the pedal.
posted by spaltavian at 2:12 PM on August 9

Can you pinpoint from what wheel the sound is coming? If so, do you feel confident enough to remove the wheel and see if you see something irregular? Could just be tons of gunk in there (this could also explain the ABS light), or a stone that's got stuck.

Does the ABS light stay on also when things go back to normal?
posted by effbot at 2:17 PM on August 9

You could be experiencing an ABS malfunction. The ABS warning light on is a pretty clear sign of that. Even normal ABS activation is generally described as a vibration or grinding in the pedal as the ABS unit dumps or applies pressure via the high speed solenoids in the system. Many ABS units run a system check on start up that involves some solenoid activation, but it's usually transparent and EXTREMELY RARE that the driver is subjected to that. Also, in the event of an ABS malfunction, the system generally puts itself in a stand-by mode that preserves conventional braking, but takes the ABS off line. But, there's always the chance that something else has gone wrong in your circumstance and the ABS, while malfunctioning, is continuing to activate. Get it checked out by a technician that has the necessary software or scan tool to thoroughly diagnose your ABS system. Take it to a Ford specialist or dealer if necessary. Expect to pay about an hour of labor for an initial diagnosis and a few hundred bucks for a new ABS module or unit, if it proves to be malfunctioning mechanically.
posted by Jon-o at 2:21 PM on August 9

I have a ford Taurus that is basically the same as your car. If I don't drive it for a few days the disks rust a little on the surface and make a grinding sound for the first minute or two of driving while the rust is eroded away.
posted by 517 at 2:24 PM on August 9

It kind of sounds like you're experiencing ABS pulsing when you first start driving. Does the pedal pulse as you depress it? It may be your ABS system malfunctioning and then later sorting itself out. That's my guess.

What others are driving at is this scenario: when you wash your car or it's exposed to moisture, rust develops on the brake rotor. When you first hit your brakes, the pad will encounter this rust, which could cause the grinding sound. I don't think this is the answer, however.

It's not the brake fluid.
posted by luckypozzo at 2:37 PM on August 9

I think I've washed my car maybe 5 times in 5 years. It's been pretty dry, weather-wise, around here for the past month or two.

It is a pulsing sound/feeling, rather than the constant grinding I've heard when you need new pads. Based on what you guys are telling me, it sounds like its a malfunctioning ABS. Which sucks.

Thanks for your help!
posted by spaltavian at 2:57 PM on August 9

Don't worry too much! You might only need something small like a wheel speed sensor.
Good luck and let us know how it works out.
posted by Jon-o at 3:10 PM on August 9

You could try pulling the fuse for the ABS to try and help troubleshoot the problem.
posted by onya at 8:40 PM on August 9

Why not take it back to where you had it serviced and ask them?
posted by scottymac at 1:13 AM on August 10

You could try pulling the fuse for the ABS to try and help troubleshoot the problem.
Don't do this. You'll clear the fault memory and, unless the ABS is seriously malfunctioning, it will take some time before the fault sets and trips the light. In the interim, there'll be no diagnostic data stored in the ABS module and the shop you take it to will have nothing to go on. Get this diagnosed professionally, rather than DIY.
posted by Jon-o at 3:48 AM on August 10

Jon-o and luckypozzo have it.

Thanks guys!
posted by spaltavian at 3:36 PM on August 13