cold engine bird chirp in "D" but not "N"

[Rhett]

Hello tranny fellas

In this thread...
http://www.explorerforum.com/forums/showthread.php?t=146928&page=1&highlight=bird+chirp

...I went through hoops to try and find the source of the cold-engine bird chirp noise I am getting. I still haven't found the cause, but I did come across something the other day that is interesting:

If it's doing the chirp, and I'm driving down the road, if I put the transmission in NEUTRAL, the chirp stops. Shift back to D, and it's on again. Now, I've never heard a U-joint do a bird chirp noise like this, but there's a first time for everything. Could it be the rear driveshaft u? But my real question for this subforum is, could this cold-engine bird chirp be somehow transmission-related? Flywheel?

 

[toy720]

yes it is very possible it a u joint as the bearings may be dry which could make a chirping noise, Is it like rotation of the drive train (chirp-chirp-chirp-chirp etc as you get faster?

 

[toy720]

is the noise coming from under the hood or under the vehicle? sorry just read the thread ?

 

[Rhett]

Well now I take back what I said. I did some more testing, and it doesn't matter if it's in N or D. It chirps in any transmission condition. I should have tested it more before I posted in the tranny forum. Oh well.

Incidentally, I am 99% sure it's under the hood. Probably a bearing in one of the pulleys I haven't changed yet (alt, p/s, a/c or crank), since it's not the belt, idler, tensioner, or water pump. The chirp does increase if you gun it, but then if you let off it stops.