I am getting a low-speed grinding or rubbing sound when I first start driving in the morning. I don't hear anything unusual when I back out of my driveway but will hear it while driving a 100' stretch to a stop sign. I will accelerate to ~10-15 mph and when I come off the gas to coast in to stop I hear a grinding sound from underneath my Runner. It's not real loud and I only hear it when I have my windows down and stereo off...it just doesn't sound right. The other strange thing is it stops making the sound after I drive ~1/4 mile and it won't do it, as far as I can tell, for the rest of the day.

The only feedback I have received from a mechanic friend is that it might be the brakes causing the sound. As humid as it has been around here he thinks the drums or rotors might be rusting up a bit as it sits over night and the sound I am hearing is the crap coming off. I don't know enough about brakes to call BS on this or not.

Any thoughts would be much appreciated. My road trip out west starts next week and the last thing I need is for something to fail on the way.

 

He may be right, that does happen. But I've never 'heard' a noise, just felt the brakes act funny.
My other truck gives me on or two grabby stops in the morning only if it was wet out. If it hasn't been driven for a few days, really grabby and real loud squeal just for the first couple stops. Then it's fine. It's been doing that for 5 years and 75k miles now and nothing has shown up to indicate a problem.

 

Check the rotors visually for surface rust before starting out, then check them again after the noise stops to see if it's gone. That's the only thing I can think of if it's stopping after driving awhile. If you want, you could probably induce this by spraying the rotors with water while cold and letting it sit overnight, then doing the test the next morning. Don;t spray them when hot or you may warp them.

 

Thanks guys. It wasn't until I was driving in this morning that I realized I should have looked at the rotors before I took off. I'll take a look tomorrow.

 

I had this same problem. When I investigated, I found out that I had a leaky axle seal that caused much of the gear oil to drain out. The low grinding sound was actually the gears rotating in the differential without much oil. Pull your rear wheels off and check to make sure you don't have a bad seal.

 

Wouldn't that cause a constant grinding sound, not just first thing in the morning? Since I replaced the diff fluid ~2 weeks ago, I have been keeping an eye on the back end, and the ground underneath it, looking for leaks. I haven't noticed anything and the inside of the rear wheels is bone dry.

 

It would tend to cause a grinding sound at low speeds where you can actually hear it. If you have replaced the diff fluid and there seems to be no leaks, then I wouldn't think that is your problem then. I guess I should have read your first post a bit better - I didn't see where you said it goes away after 1/4 mile. I could believe that it is condesation causing a bit of oxidation on your rotors like the mechanic said.

 

No sweat Runner4...I appreciate the input.

 

I have the same type symptoms. but it is not a 1 for 1 sound that goes with the tire rotation. it seems to be slower than the tires. maybe once every few seconds. but it also goes away after a few min in morning then not for the rest of day?? any ideas?