What's going on with my car?
May 16, 2013 9:19 AM   Subscribe

My 1998 Volvo S70 has been making an audible whirring/grinding noise when driving and braking. It's intermittent (though lately, it's been happening daily), unable to replicate reliably, occurs when driving at slower speeds (less than 35 mph), and occurs multiple times within the first 15 minutes or so of turning the car on and driving. No dashboard lights have shown up and the mechanic can't replicate the problem or figure out what's happening. What's going on? (additional details inside)

Additional details: Usually what happens is that the car will make the whirring/grinding noise while driving and then if I brake soon after that, the brake will seemingly lock up (as though the ABS were malfunctioning) for a fraction of a second, and then let me brake with a minor jerking kind of motion, all while making a grinding noise. The brakes (for now) still seem to work fine, otherwise. I've been keeping my distance from cars in front of me in the meantime.

The issues occur regardless of whether the engine is cold or hot.

Another snag is that this will happen multiple times for a few weeks and then will be fine for a couple of weeks before starting up again. Anecdotally, I feel like now that it's started up again, it's happening more frequently throughout the day.

The mechanic (whom I trust) has looked at the brakes and the ABS system and says there doesn't appear to be anything wrong with either. He was unable to replicate the problem when I left the car with him for a few days about a month ago.

Any ideas? This is driving me (ha!) crazy.
posted by lea724 to Travel & Transportation (7 answers total)
Caliper is stuck closed? That happened to my 99 S70.
posted by ian1977 at 9:21 AM on May 16, 2013 [1 favorite]

Is the car rusty? and do you live somewhere that uses salt on the road in the winter? Rusty/dirty brakes can makes this noise. The best way to prevent rust (anywhere on the car) is to wash frequently in the winter, and especially in the wheel wells. Also really, really wash out the brakes inside the wheel. I use a high pressure hose (the DIY wands at the car wash are great) and hit both the inside and outside of the brakes inside the wheel to clean the salt/grime/brake dust out.

If that isn't the problem than likely your ABS pump and/or valves are sticking. Several things can cause this and some are easy to fix and some are hard. The easiest is dirty brake fluid. How dirty is your brake fluid? (it should be clear-if the brake fluid is black/grey and smells bad it needs changing). Changing brake fluid is pretty easy and cheap (compared to changing the master cylinder and/or the ABS stuff) and should be done every few years. If that doesn't fix it the next thing would be to take of the calipers and see if they are rusty/corroded (when the brake fluid is getting changed you have to 'bleed' the calipers and you will get a pretty good idea then about the conditions in there).
posted by bartonlong at 9:35 AM on May 16, 2013

Have your mechanic do more than look. They will need to take the brakes apart to see if the pads are stuck or a caliper piston is stuck.
posted by alfanut at 10:10 AM on May 16, 2013

Sounds like a sticking caliper.
posted by stenseng at 11:02 AM on May 16, 2013

Hm, the whirring noise sounds exactly like what happened when the ABS control module started to go on my S70 - it was inconsistent, but usually happened when going over rough pavement. No dashboard lights for a while, but the ABS light finally did come on and stay on. I don't remember if a mechanic gave me an official diagnosis, or if I found enough consistent corroborating Volvo forum posts to make decide on my own that the control unit was bad, but I wound up replacing it. I was able to find one at a junkyard for $100, and with another $10 or so spent on a special E5 Torx socket I was able to fix it in about 15 minutes. It's been fine since.

I didn't have the grinding/lock-up issue, though.
posted by usonian at 11:06 AM on May 16, 2013

The symptoms you describe a are consistent with the brake pad rubbing on the rotor. I would consult a competent mechanic. The chap you previously engaged is obviously a numpty.
posted by BenPens at 5:23 AM on May 17, 2013

Response by poster: For anyone interested in knowing if I ever found a solution...

About a month after I posted this here, my battery died and once I jump started it and started driving again, the car was acting like it might have been the alternator, so I ended up bringing the car to the mechanic.

The mechanics took a look at it the next day and said that it wasn't the alternator, it was just the battery, so they replaced that and while they had the car, they looked over a few other things, replaced the rear brake pads, and (here's the part where I don't know if I'm repeating this correctly, because I am truly clueless about cars) they went into the boot to fix something there. While they were there, they had to move some ABS wires, but the wires were apparently super corroded and as soon as the mechanic touched them, they fell apart. So they had to order in new wires and put those in.

I picked the car up from the mechanic's on June 14 and it's now a month later, and I have literally not had one single issue with the car behaving as it did. I can only assume that the ABS wires that they replaced were causing the issue with the grinding/whirring noise as well as the jerky brake movements.
posted by lea724 at 9:54 AM on July 14, 2013

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