I have noticed a grinding sound coming from what appears to be the rear of my van (in the center) when I start to accelerate. When I first push on the gas pedal, I hear this grinding sound. Then, when I push the gas pedal a little more, it goes away. Also, I sometimes hear it when I apply the brake pedal (though not often).

I've noticed that it usually happens when I first start driving. After I've driven for a minute or so, I don't usually notice it anymore. Sometimes it'll happen after I've driven a bit, but rarely. Almost always happens right when I first start driving.

I noticed that it doesn't happen if I push the gas pedal with the car in Neutral. Only if the car is moving.

Also, if I'm coasting downhill when I first start the car, without pressing either the gas or the brake pedal, I can hear the noise. But then the noise gets much louder if I press the gas pedal a little.

I don't hear it if I have the windows open and the wind is blowing in. But when I have the windows closed, I can hear it as though it's coming through the floorboard at the rear of the car (in the center).

At first I thought the transmission fluid might be low. But it was only 1/2 qt low. And it's still doing it after I filled it up.

Any ideas on what this might be? It just started a couple of days ago. Perhaps when the car is shifting from 1st to 2nd gear or vice versa?

Car is a 2003 Dodge Caravan SE (automatic) with about 85,000 miles on it.

Thanks!

Neil

 

Would not be the transmission as that is in the front of the car. Quite possibly, the brakes are dragging a bit, or the rotors are getting a slight build up of rust from condensation. I would suggest pulling the rear wheels off and inspecting the brakes.

 

Thanks for the reply. It really does sound like it's coming from under the floorboard in the center-rear of the vehicle, like where the rear axle is. I've had brakes make noise before. And you could hear the noise better with the windows open (especially if you're next to a wall to bounce the sound off of) than with the windows closed. Here, it's the opposite. I don't hear it with the windows open, but if I close the windows, I can hear it coming through the floorboard.

Also, as noted, it only happens for about a minute when I first start driving the car. Seems if it was related to the brakes it would happen continually.

Thanks.

 

Not if its just surface rust on the rotors that gets scrubbed off the first couple times you use the brakes. Do you have disk or drum rear brakes? Sorry did not ask that before. The situation I am describing would not be for drum brakes, only disk. At any rate, it would be worth it to pull the wheels and have your brakes inspected. Thats the only thing turning on tyhat end of the vehicle.

 

Yes, they're drum brakes. Possible that a spring holding the drum broke? Not sure if that would explain it.

 

Could very well be inside the drum. Only one way to check.

 

RESOLUTION.

Decided to take the car into City Garage. Turns out that all it was was the clamp holding the exhaust pipe had worn down, and was not holding the pipe tightly.

I guess when I started to press the accelerator, the frequency of the vibrations hit the resonant frequency of the pipe and caused the loud vibrations. Then, when I pressed the accelerator more, the frequency increased and the sound went away. Only when I hit that "sweet spot" of just the right frequency did it make a loud sound.

That also explains why it stopped doing it after a minute or two. I'm guessing the exhaust pipe heated up and expanded, and then was tight against the clamp, so it didn't make the noise anymore.

I had my oil changed while I was there, and they didn't charge me anything for the repair. So that worked out well.

Thanks for your input.

 

Glad you got it fixed. Sometimes it's hard to diagnose a noise over the internet. I've always been one to get into it and start shaking things, inspecting moving parts, etc. Guess I'm more of a do-it-myself-er.