grinding/rumbling noise when braking

thepizzaman · Post by **thepizzaman** » 21 Mar 2016, 10:31

Hello All-
Desperately hoping someone can help me before I get frustrated and put a brick on the gas pedal and drive this car off a bridge...

A few days ago, out of the blue, while pulling up to a stop light, I noticed this grinding noise. The best I can describe it is as a low grumbling/grinding noise that sounds like the grinding noise of worn out brakes yet less metallic. It has has been reoccurring ever since and happens every time I come to the slow end of the braking session (around 5 m-10 mph), never while braking in reverse, and usually continues at a slightly lower level upon idling. Reading previous posts, I had my mechanic check the braking system; the pads, rotors and everything else appeared fine. I could tell he really wasn't sure of the cause and was just guessing that it might be a bad engine mount. I thought it might be the ABS module since the speedometer has never worked and the ABS light has always stayed lit up since I bought the car a few weeks ago. I removed the module, took out the abs fuse, and the problem persists. I do know I need new front struts, a lower engine mount and eventually a new front axle, but am not sure if any of these are the cause of my immediate troubles. I didn't spend a whole lot of money on the car but don't have a lot to waste on issues that might not fix the immediate problem. I use this car for work delivering pizza so I need to get back on the road as soon as possible. Any suggestions would be greatly appreciated.

Sommerfeldt · Post by **Sommerfeldt** » 21 Mar 2016, 11:58

Hey

We've had a few posts of this thing the last months - I've had it on my car, and there's been a couple of others. In my case, the problem only seemed to surface when the brakes are warm, but it would be intermittent. As far as I know, we haven't been able to pinpoint the reason behind it. My issue stopped when I changed pads, discs and one rotor a week or two ago, but there was nothing obvious. One caveat: one of my calipers was stuck - it wouldn't retract the whole way. This was likely a pretty old problem, since there was rust and BS all up in there.

If your mechanic didn't check if the caliper pistons are able to travel all the way back in, that might be something to consider. Other than that, that sound has me just as baffled as you. I don't know about you, but in my case, it didn't seem to impact the actual braking, so I let it be, knowing I would change the brakes when temperatures were up in the reds again.

- S

Post by **misha** » 21 Mar 2016, 12:05

Are the brake pads at the end of their life with around 5mm of friction material left?

Post by **regent** » 21 Mar 2016, 12:13

It could be the pads or even a hub bearing 'on the go' - or it could be a very easy one - like a rotor touching a bent dust shield.
I would attempt to duplicate and localize the source (maybe a particular wheel), and then do a thorough visual before taking stuff apart

Sommerfeldt · Post by **Sommerfeldt** » 21 Mar 2016, 12:22

regent wrote:It could be the pads or even a hub bearing 'on the go' - or it could be a very easy one - like a rotor touching a bent dust shield.
I would attempt to duplicate and localize the source (maybe a particular wheel), and then do a thorough visual before taking stuff apart

The dust shield is a good tip - I forgot to mention (or consider, really) that I removed quite a few tiny pieces of gravel from behind the dust shield when I changed my discs. I think the fact that the sound isn't really very metallic (like OP said), made me dismiss the possibility of the dust shield being the culprit... But it's worth a check, OP.

- S

thepizzaman · Post by **thepizzaman** » 21 Mar 2016, 13:13

Thanks so far everyone. I kind of figured it didn't have anything to do with the brakes since the noise often continues after I have stopped and am idling but I'm willing to consider anything at this point. Will have the mechanic check out the possibility of bad calipers, hub bearings and dust shield when I see him tomorrow. Last time he took off the wheels I could see the brake pads were in good shape though.

PeteB · Post by **PeteB** » 21 Mar 2016, 13:21

I hope that your calipers don't look like this: https://www.matthewsvolvosite.com/forums ... 6&start=10

https://www.matthewsvolvosite.com/forums ... =24633&t=1

We had a droning/rumbling noise when applying the brakes, the fronts looked fine.
The picture is of the rears and my theory is that the frozen pad caused the other
pad to bend the rotor when the brakes were applied. We replaced the rotors
when probably all that was needed was calipers and pads.

Post by **abscate** » 21 Mar 2016, 18:16

On a careful reading, a noise which continues after the car is stopped isn't brakes.

It's alternator, power steering pump, possibly AC compressor or top end of engine maybe