when i start the car cold i hear a strong vibrating noise coming from under the hood. the noise is directly in front of the drivers position. problem is it only makes the noise when im driving and at about 1k-1.5k rpms so i cant hear it at idle(noise goes away over ~1800 rpm's)

when i look under the hood it seems like its coming from under a black cover thats right near the brake fluid container(sorry i dont know names of parts)

after a few minutes the noise goes away.

any help?

 

Does it only do this when it's cold?

 

I've searched online and haven't found anything about this issue but my vehicle does the same thing. I have a 2003 4Runner V8 Limited and usually when I start the vehicle, it will make a humming/whistling noise for may 5-20 seconds and then stop (not loud but noticeable; especially when stopped). When driving, the noise will return and then go away here and there. It seems to happen more often when the engine is cold but can't really say that it correlates with braking, accelerating, etc. The noise does seem to be coming from the brake fluid container under the hood near the driver's side dash area. I thought I'd piggy back this thread before posting one of my own to see if you ever determined the issue.

 

i have the same exact problem on my 96 4runner sr5. the black thing, i was told, is the vacuum. i dont notice it when the truck is running but when its off i do. i cant figure out why its making the vibrating noise either.

 

94 3.slo I had a rattle or vibration in the same area that I could not find. I happened to be running some SeaFoam through it and noticed I was getting smoke out of the exhaust manifold to crossover pipe connector. I tightened up the connector and the noise went away.