Whining at 1500 rpm?
 

Hey, hope I can get some help here. I have started to notice a kind of whining noise from my 2001 chevy silverado. The noise is only present while driving, doesn't happen if am revving in neutral. Just the other day I brought it in to have the shop take a look and they replaced a u joint, but I am still hearing it. To clarify I only hear it when around 1500 rpm, often times I'll accelerate and hear it briefly as the rpm's pass 1500 but if I sit with it at 1500 and with my foot on the gas, its a constant whine. Any ideas? Thanks

Does it happen right around 35-40 mph? Only on acceleration, not on deceleration? Sound like it's coming from the front or back of the truck?

I'm getting a similar thing on my 07 Silverado. Turns out my power steering pump has a slight whine in it.
My steering performance hasn't changed... still good.
No whinning at idle or at higher speeds
But it is more apparent at slower speeds around town
This is one of the bad things about chevy power steering pumps, they are very unforgiving if you let the fluid get low

From what I have noticed it is on both acceleration and deceleration, as long as I have my foot on the gas and the rpms are at 1500 the whine is present. The speed doesn't seem to be a factor really, can be whining when just leaving a stop or if I'm going towards the 40 mph range. The sound definitely seems to be coming from the front of the truck. Thanks for all of the responses!

I've read other places that replacing the steering pump might not solve any of the noise issue, but if it is the steering pump is there damage being done if the whining is heard?

As I understand it, if it is the PS pump whining? The damage is already done. I'm going to drive mine until I notice a lack of PS performance.

So your whining sound is effected by RPM not speed. So it must be sourced on the engine. Water pump, Alternator, or even a belt tensioner.
I understand it is heard to pin point the which it is... It sounds like it is a bearing going bad on one of these components, all I can suggest is maybe after driving it for a while, feel each of the pully points to find the HOTTEST

thanks for all the insight thus far, one last question though, or bit of information I guess, is that it doesn't happen every time I drive, which I find kind of odd I guess? I make mainly short trips but always let it warm up before I go anywhere (I live in ND so its pretty flippin cold).

I agree with in2trux, It's most likely a pulley. The idler pulley on my old 96 silverado did that right before she got retired. It was an easy fix, and simple diagnosis. I used an automotive stethoscope to listen and find the loudest noise on the drive belt system. I used the tip of it to touch the bolt in the center of the pulley, and found that when the engine was running there was a very loud noise coming through the earphones.

Or if you don't have access to such things, you can use a long screwdriver. Touch the end of the screwdriver to the pulley, then put your ear on the plastic handle side and carefully listen through the screwdriver.

Another option is if you take the belt off, spin each pulley by hand and see if you can feel any with a grinding or rough rolling feeling to it. If you find any that roll roughly, it's probably that pulley making the noise.

A bearing just beginning to go bad can can seem to come and go. I would guess do to the ambient temperature and humidity level. Eventually it will be noisy all the time. (Not for long though, until it grenades)

As Nullhead describe is a great way to quickly find out which bearing is going bad.

https://www.youtube.com/watch?v=m_GFRQDMLeE