When in motion ( and often but not always), the van makes a "middle c" pitch hum that moves lower on the scale as I slow down, and fades out when stopped. It is more pronounced and more predictable when we are driving on the highway, or the engine is warm. It has a somewhat computerized element to it, and our first thought was that it was related to the power steering, because of the "power/computerized" feel of it, but it also seems to related to transmission activity. My husband describes the noise as a kind of whirring, but that doesn't ring true for me. It's more electronic sounding to me.
My car has 135000 miles.
My car has an automatic transmission.
Hi there. The noise that you are hearing could be the power steering pump whining, the alternator bearing failing, or the transmission gear train has too much gear lash. Check the engine to see if there are any noises when running at a stop with the transmission in park. When revving up the engine in park and there is no noise, then the noise is with the transmission. If the noise is there with the engine revving up in park, then shut the engine off and remove the drive belt. Turn all of the accessories pulleys and see if any of them have a bind or noise to them. Then with the belt off, start the engine and see if the noise goes away. If the noise goes away, then an accessory is making the noise and should be addressed. If the noise is still there with the belt off, then the engine is making the noise. If you need further assistance with the noise as your vehicle is driving down the road, then seek out a professional, such as one from Your Mechanic, to help you.
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