Hey Guys,

So I've had my 4Runner for about 3 weeks now, and this is the second time I've checked in with a strange noise. The first time it was just the accessory belt (tensioner needed adjusting) but now it sounds a little more serious...

When idling and accelerating, there is no problem. As soon as I lift the gas pedal, a squeal begins somewhere under the hood or by the wheels. The squeal sounds like rusty bearings or something- similar to the sound the clutch in my old Mustang made before it went out. The squeal continues until I come to a stop. When I brake, it seems to go away but I think it's just because the vehicle speed is reduced. The noise correlates with vehicle speed, not engine speed. At idle, I can rev the engine and there is nothing strange, and when in motion I can put the tranny in neutral and this has no effect on the squeal. Sometimes I can hardly hear it at all, but it seems to get worse the more I drive. After a long commute today, it was audible over my stereo, heater fan, and road noise even with the windows shut.

I'm hoping it's something as simple as brakes, but fearful that it's more serious (cv joint, wheel bearings, even transmission)... honestly I have no idea.

Have any of you had an experience with a similar issue? Any mechanics out there who could speculate as to what might be going on? I'm not really comfortable doing much work myself, but I am willing to take it in. I just want to have an idea of what it might be before I do.

Thanks in advance for any advice! It's times like this I am glad to be part of such a great forum as this!

First thing I would do is lift front end up and spin tires manually to try and locate the sound.

I am going to go ahead and take a stab at it here.

I believe the noise to be your brake pad wear indicators. They are little tabs of metal that rub against your rotors making that awful noise when you pads get wore down. If you keep driving it the sound may/probably will go away, but brake pads are easy and cheap ($30-40) to fix. If you wait to long then you may have to replace the rotors also, which will be $100 more.

Jack; Socket set w/breaker bar for calipers; Hammer to rap on caliper to free it from the hub. I use a dead blow. 8" C-clamp to squeeze your pistons back in. Make sure to use your old pad to clamp against versus clamping directly to caliper piston itself. When you clamping open up your brake fluid reservoir and lightly stick a wad of paper towel/rag over the top to soak up extra fluid that you push back into it. Just toss the rag when your done. A can a brake cleaner is handy to wipe down the rotors before you assemble everything back. No bleeding required.

Sorry to explain it all, if you already know what to do. Just trying to lay it out for you if you don't.

I would say brake wear indicators, but as you describe the sound the wear indicators would squeal upon braking.

More detail is needed here, as there are many things that could be wrong.

it could be dragging a pad on the rotor, or debris stuck on the pad surface with contact on the rotor.

bearing of some sort

like i said more detail is ideal for a resolution.

Bump and just a thought after I thought about it, you did go off roading recently? I would think there is something in contact with the rotors. Take a hose and flush the caliper down good, if your lucky that will wash it out or you might have take the caliper off and pick at it that way. Either way I think that is the problem, debris could be rust, rock, large sand grain who knows.

Thank you both so much for the help.

After driving it more in this condition, and after reading your posts, I went to the car wash and sprayed out my wheels (yes, I had done some light off-roading recently) and had a can of disc brake quiet laying around that I sprayed on the discs after they had dried.

This simple 'solution' COMPLETELY got rid of the noise. It's a relief to find that it's just the brakes. Now I can't decide whether it was just some dust or debris stuck in there, or if the pads really are worn and the disc brake spray was just a temporary band-aid. I'll at least take the wheels off the check out the pads this weekend.

Either way, this is the second time I was worried over nothing.

Thanks again guys, and happy trails...

Nice good to hear you got it all settled up! I spoke from experience i had just a little tiny small itsy bitsy piece of garbage stuck in a pad that did the same thing. If your look closely you might be able to see a little scour on the rotor where the so said debris is/was at.