Ahhhhhh, the weirdness never stops...
Both my Minivans make a howling/dry bearing noise when they're cold...as in cold out...not operating temp.
I've owned one van for 10+ years, and for years, when the temps go into the 20's or lower it would howl occasionally...
Over time it got to be a regular thing...but only when it's seriously cold out.
NEVER heard it in any kind of warm weather.
Now, with this incredibly cold weather we're having around here, I've heard it the same noise in my other minivan!
Here's the situation in Van #1...
Not an engine related noise. I've shut the Van off while it was moving and howling...noise continued until the speed dropped.
You have to be moving.
At least 20 mph or faster. It will continue to around 50 mph, then it stops.
It's quite loud, and definitely sounds like a dry bearing somewhere. It has that variable pitch warbling noise like a dry bearing.
In Van #1 it is speed related. Both noise level and pitch change with speed, but it will stop around 50 mph.
Van #2 it only seems to occur at lower temps (10 and below), lower speed (10-15 mph), it isn't as loud, and seems to go away or get much quieter as speed increases over 25 mph or so.
I have wondered if the cooling fan might be the culprit...freewheeling from the airflow through the radiator...although both fans do not seem to have excessive play in them.
Feel free to throw out any ideas that might occur to you...but it's definitely not tiny little wolves in the engine compartment...I checked.
Thanks in advance...
CG