Howling harmonic noise from right front

I have a noise problem from the front passenger side. It is 96 Windstar with 120K miles. The noise started about a couple of months ago, and the intensity goes up and down as the car moves. It howls like UUUUNG(loud) – uuuung ( weak) – UUUUNG (loud) – uuuung (weak)….like a harmonic wave.
The frequency is not the same the tire spinning frequency. It is about 4-5 times less than the tire spinning frequency. It is NOT coming from the tire since the noise is the same with a new set of tires. I took it to a shop and they gave me a long list of possible sources. But I do not want to replace parts blindly. Any insights will be appreciated.

It hard to say...! I have a 2000 model with a similar noise situation coming from the right front tire as yours and so far I've rotated the tires, replaced the wheel bearing hub and installed a CV Joint Axle and the noise is still there. So I don't think it is as simple to diagnose as one might think.

Things to look for...
Does the noise changes as you speed up, slow down or if stopped? How about when the vehicle is under lateral loads like taking a highway turn, putting more weight on the right side tires than on the left ones or vice versa for example.
Does it make it vibrate or shake the vehicle?
Is it constant, or does it stop doing it at any point?
If you're driving at say 45MPH and throw the tranny into neutral, does the noise persists?

Also, you could try to safely and securely lift the right front of the ground with a good strong jack -make sure you chock all other wheels and put the E-brake on and support the vehicle on jack stands and have a helper run thru the gears... Low to Hi and Reverse to see if there are changes in noise or vibration to rule out the tranny. Then try to look from a far (not in front or getting under the van) to see it the axle wobbles, oxilates or shifts violently. Also take a look at the Engine Mounts, Exaust Pipes & Shields and any loose metal to make sure they're in good shape.

If you don't want to do the work yourself or throw parts at it, take it for second opinion to a reputable mechanic or two and have them check it out.

That's all I can think off right now... I now you'll be getting more help from other members soon.

Thanks for the reply… here are some more informations.
“Does the noise changes as you speed up, slow down or if stopped?” – the noise is in sync with the car speed (or tire rotation). But the frequency of the noise is much slower than the tire rotation frequency.

“ How about when the vehicle is under lateral loads like taking a highway turn, putting more weight on the right side tires than on the left ones or vice versa for example.” – the noise is much worse when I make a left trun.

“Does it make it vibrate or shake the vehicle?” – the car runs fine until it reaches 60 mph and there is some vibration. But the vibration almost disappears above 65mph.

“Is it constant, or does it stop doing it at any point?” – The noise almost disappears if I turn the tire slightly right on a highway (like changing the lane).

“If you're driving at say 45MPH and throw the tranny into neutral, does the noise persists?” – yes, the noise is the same in neutral.

I also lifted the front off the ground and ran the engine with gear in D. But I could not hear the noise. But it was a bit scary, so I did not do carefully.

I had the rumbling from the front on my 2001 LX at around 75Kmi. Very noticeable at 30mph and 60mph. It was magnified on right turns. It was the front left hub. When you make a right turn, it shift the vehicles weight to the left, putting more force on the left bearing and makes the noise louder. (just a quick diagnosis technique) A local shop charged me ~$250 to replace the front left bearing hub assy.

SamNovice, I must admit that the info you provided steers me to believe a failing wheel bearing hub is your problem. But, after the experince I had with my Windstar I can't be 100% sure.
have a check here (http://www.automotiveforums.com/vbulletin/showthread.php?t=716386&highlight=Ed_Strong) so you can see all the steps I went thru and maybe it might make an easier process for you!

I just repaired the same symtoms on my 98 Windstar. In the fan belt system, you need to replace the belt tensioner and the idler. You should also replace the belt at the same time. This will stop the howling noise. For belt diagram go to: http://www.mvreader.com/multiview/dayco/zoom.php?zoom_item=C0001X&l=n&catalog=auto&category=2

http://www.mvreader.com/multiview/dayco/graphics/rtdiag/blg.jpg