It started happening about 3 months ago. I'm pretty certain the noise is from under the hood. It sounds like a motor running. It's not the engine. It's a totally other rotating device it sounds like. You know that humming sound. The loudness of it is proportional to the speed. The faster I go the faster and louder it hums. I still drive the car, but the sound irritates me. I don't like the feeling or something not right with my car. Anyone have any idea what it is?

My car is a '98 Honda Accord, 4-cylinder, 4-door, manual transmission.
I just recently replaced my brake pads and discs at the front and didn't see anything there that could cause the noise.

 

Is it constant, or does it go on and off?
Does it only make the sound when you're moving, or anytime the engine is running.

If it's constant, and when the engine is running, it could be bearings going bad on alternator.
Ifthe soundgoes on and off, could be a/c compressor.

 

it's constantly on. and it gets louder the faster i go. and vice versa.

 

Sounds like a problem with the belt or pulleys. Have you changed the belts recently or inspected them? The tension may need to be adjusted.

You could take off the power steering belt and start the car to see if the P.S. pump is causing the noise. You can try the same with the alternator belt, just don't run the engine for too long. Spin the pulleys with the belt removed and try to listen for a rumbling and make sure they are spining smoothly.

 

there's no noise when i'm idle. even when i rev it when idle, there's nothing.
it's only present when im actually moving.

 

Sorry, I didn't realize that. If it is making noise while driving then I would think that the tires, CV joint, or wheel bearing are likely suspects.

My first guess would be the wheel bearing since you described it as a rumbling sound. You can jack up the front end (use jackstands) and try spinning the wheels when in neutral. If you hear the humming sound, the bearings might be going.

Get the tires rotated (if due) and see if the problem goes away to eliminate tires.

Inspect the boots on the half shaft for tears. A C/V joint ususally makes a clicking sound when it is going bad.

 

thanks. i'll try that.

 

check transmission, MT liquid, and does the clutch feels any different?