My son helped me out by recording a short example of my whistle problem. It only whistled for a short while and then didn't want to do it again - as I said before it" intermittent. This was shot with the engine cover off, so there's lots of air and road noise. sure don't sound like a bearing to me. I'm trying to attach a link, not quite sure how to do this- you may have to type the link in?
http://www.youtube.com/watch?v=SHuD51TklXo

 

You appear to have a gremlin who is running a wetted finger around the rim of a crystal champagne glass.

Too lazy to reread the whole thread. Does it do it when not moving?
Any chance it is a door or window seal. Does the noise change if you crack a window. Change fan speeds?

That type of noise will be very hard to pinpoint, but have you tried the length of hose to your ear yet?

 

Only when driving, window up, window down, with the wind , against the wind, any speed, fan on or off. A mechanic friend has offered to ride shotgun with a hose to his ear. I'm grasping at straws here.

 

Here I go again... because that noise sounds exactly like a squealing bearing.

And to answer your last question to me about having the noise for a long time. The bearing is a roller (ball) bearing and can roll for a very long time with minimal grease. Often people drive very long times with dry noisy bearings simply because the cannot hear them. With a van the engine is a lot closer and it's easier to hear these kinds of noises.

 

On a friends pickup truck we narrowed down a very similar squeal to a camshaft bearing. That is not the whistling sound I thought you were describing.

This may be more internal to the engine or since while only driving may be more likely in the transmission.

 

This sounds like an A/C compressor whine that will kick on and off randomly in cold weather.

Does the van have A/C? Try unplugging the electrical connector to the compressor. Then drive in the cold at any speed and adjust the heater/blower controls from low-med-high and all of the vent out positions.

The A/C compressor is designed to kick on when defrosting the front windshield regardless of the temp outside. In the winter, I leave mine unplugged.

The colder it gets the louder an A/C compressor whine will become due to the frigged temps upon the coolant charge and pressure. The A/C compressor can not draw enough lubricating A/C oil into self and will whine.

Still investigate the bearing issue, you never know.

 

Thanks Stev, Tried shutting heater controls to "off" while driving so the compressor would't cycle. the noise is still there.
I forwarded the video clip to the dealership that put in the short block - service manager agreed the noise would drive him crazy too. He suggested it sounded like a problem with the intake and to pull it and check it out- check for restriction. I might go to the wrecker's this weekend and see if I can find another intake and clean it up- do the mod shown elsewhere in this forum and replace the crap sheet metal belly pan with something like the hugh's plate. Sounds like the engine can't breathe ?
Might also get a chance to get a friend to ride shotgun with a hose and see if he can pinpoint the noise this weekend.
Can anybody tell me what kind of vac readings should I be getting at highway speed in overdrive? 10" sounds awfully low.

 

Just turning off the controls on the dash to keep the AC from cycling may not totally work. Only the electrical connector is a true shut-off. My van would cycle the AC compressor even if the system was fully off while at highway speeds. I'm not sure why it does that.

 

Is there a round gasket between the air cleaner and top if the throttle body? If not add one and see if the noise goes away.

 

Yes, there is a gasket. In the original post I mentioned driving with the air cleaner assembly off - still whistled