When a loud humming accompanies the normal low noise of the water pump, does that mean the pump is going bad?

The humming is very noticeable and can be heard over normal road noise even while driving.

Can you locate where the hum is coming from? Is it there all the time or is it intermittent? Do you hear it when the car is stationary? Does it change with the speed you're driving? I have read post regarding faulty belt tensioner and bad harmonic balancer that might gove rise to this type of noise.

is the noise coming from the drivers side??

Yes, it seems to come from the drivers side close to the steering column.

It is definitely coming from the driver’s side. It is very noisy when the engine is first started, and sometimes stays for just a few minutes, sometimes longer. The noise continues for a few minutes after the engine is shut off.

It can be very loud, sometimes more quiet. It can fade away, and return a little later.

I wonder if it is the e-box fan noise

What is an e-box and where exactly is it located? I could take a pipe and try to locate the noise.

Maybe we can narrow this down.

The e-box is the box that host the fuse and all the electonic modules. It is the big black box right behind the windshield washer reservoir. Be careful when you open the lid of the fuse box. The two little tabs are very flimsy and will snap. Fortunately it only cost 50cents each. The e-box has a fan to remove moisture. Mine will chirp if the weather is cold. If you go to kenyee's site there are instructions for cleaning the fan. It involves opening the box and pushing wires around to get to it therefore I didn't bother to do it myself. There was a link to an illustrated page of how to do it, unfortunately that link is dead. My dealer does not know about the fan problem and whereabout it is therefore I didn' t even try to have mine replace by the dealer although my truck is still under warranty. If it ain't too broke, don't fix it otherwise it will break.

I doubt its the belt tensioner.. if u look down into the engine, you can actually see it.. its near the ground, maybe it is the e-box fan

I was reading this post because I suffered from a mystery noise also and it turned out to be the Harmonic balancer. Your problem does not sound like it's the balancer but if it turns out to be the water pump it would be a good idea to replace the Harmonic balancer also. Your in there already and the part is pretty cheap, and likely more reliable then the factory installed one.
If the balancer fails at highway speed it could do a lot of damage... so much so that you better hope you're still under warranty because your talking about much $$$$.

How long did you have the noise with the bad harmonic balancer? The reason I ask is I want to know how much warning do I have before the engine self desrtuct if you have a bad harmnic balancer.

When the balancer fails it does so in a very big way, and quickly.
My wife heard a "whomping" in the engine compartment for about 10 minutes, the amount of time for her to get home.
In stop and go traffic, the car was difficult to drive, stalling at times. Too late... the damage was done. Fortunately the balancer only scored/scratched the timing chain cover. If the car was driven for any longer it would have gone through the timing chain cover! An engine rebuild would have been needed.
I'm not a mechanic but I believe the front of the engine would have to come apart and the upper and lower oil pans would have to come off/possibly be replaced. At the time the vehicle only had 50,000 miles on the odometer.
It's a fast fix, and cheap too. The whole thing, parts and labor, was about $400. Not much for a piece of mind.

Thanks for all the responses.

Yes, in fact, it was the e-box fan. I took it out, cleaned it and lubricated it. It is quiet for now.

Thanks again.