[dawgMobile]

3/4 of the way down a rough gravel road; (gravel and larger rocks in road) from summit lake near rainier, the blue meanie (2010 na) started making a horrible metal grinding sound somewhere in the back (sounded like back driver side). We (DW & I) stopped and looked underneath. saw nothing. Motion seemed to start it right up. We were well out of cell range; 3/4 of the way up a forest road, getting out of there seemed the best plan. So we drove another 2 miles and the grinding stopped. No other problems were evident the rest of the journey (while the car got 9mpg according to the meter going up the mountain; going from a town near by to home we topped 30 mpg for the first time--according to the meter, not real mpg).

So we're about to take a vacation, wonder what I should have checked. It's one of those frustrating situations, since the car is not longer symptomatic.

Ideas about what happened?
Things I should tell the dealer to check?
I figure if anyone would know, you guys would

 

[frogstar7055]

Sounds like a rock got in a brake rotor cover.
Rock get ejected,no more noise.

 

[Kevin]

^ agree. Next time, stop and reverse for a while will usually clear anything stuck in there.

 

[dawgMobile]

Great, thanks. Do I need to have the brakes checked?

 

[frogstar7055]

Just visually inspect the rotor.
Doubt it did any damage.

 

[SubieOutlaw]

save time and money. Remove the wheel and remove the rock. It is unlikely to get driven free.

 

[Blue Fox]

Happens to me all the time in sand with little pebbles in it. Mine usually just go away within a mile or so, or reverse works sometimes as well. This also happens to me when I go through deep, chunky mud with little pebbles in it too.

At first, it freaked me out, thinking I broke something, then I read the posts on here about the whole pebbles between the rotor and rotor shield. When I looked, I had one or two, but they came right out. I'm thinking about removing those as well.

 

[Elmy]

I'm thinking about removing those as well.

+1 They are annoying everytime that happens.

 

[SubaCool]

Brake shields behind the rotors are a good thing to have, I'd leave them on (Blue Fox).
DM, just get under the car and with the brakes cool, bend the shields out of the way a bit. Not much is required, just a small amount. You'll increase the brake cooling and the small pebbles won't get stuck so easily. They still will, but they'll come out easier. Also, when venturing off the pavement, keep a long flat screw driver handy. That way, if backing up won't dislodge the rock, sticking the screw driver in between the rotor and the shield and prying on it will loosen the crud out :icon_wink:

 

[dawgMobile]

Brake shields behind the rotors are a good thing to have, I'd leave them on (Blue Fox).

Are there any available for SH?

 

[frogstar7055]

Are there any available for SH?

Hmmm.........it should come with them.

 

[ESC2011]

Resurrecting this since it just happened to me today. I was 7 miles up a steep rocky trail (about 17 miles total away from cell phone service), which right now has a few inches of mixed mud/snow on top. I got up to the top, stopped for a few minutes, and as soon as I started to head back down, I heard a loud metallic sounding clang and then a loud grinding noise. I was horrified and thought it was something in the engine or transmission that just broke/exploded. I checked as well as I could under the car and didn't see any obvious suspension damage, but I was still convinced something mechanical had broken. I shut the car off thinking maybe the transmission was overheating from the steep, slippery climb up the trail and left the hood open for about 15 min to cool everything down a bit. After spending those 15 minutes wondering how many thousands of dollars a tow truck would cost up there, I got back in, started it up, slowly rolled forward in neutral and discovered the grinding noise was gone. I made it back down the mountain leaving it mostly in neutral in case the transmission was damaged. Got back on paved roads and drove home expecting an imminent catastrophic failure, but the car seemed to be handling normally. I immediately googled "metal grinding noise after driving down rocky trail" and found this thread, which I think explains exactly what happened to me (rocks suspended in the muddy slush scraping against rotor). I thought bumping this thread might help someone else who didn't know this was a thing that could happen.

 

[Gale Hawkins]

^ agree. Next time, stop and reverse for a while will usually clear anything stuck in there.

That was how I fixed the noise the second time it happened to our 1985 BMW 528e. I was at a steep hill and just let it roll back down and it cleared itself. Typically the sound is the worse part. Thankfully that road is now paved.