2003 Ford Taurus w/90,000 miles
It has been making a rattling sound almost like a light grinding sound. By ear it sounded like a bearing going out on an alternator but that tested out fine. It seems to make it most often when it has sit overnight and then is started up. The tempreture took a 30 degree drop in one day here and that was when it started. The noise comes and goes. Any suggestions?
Is this noise present only when standing still before you start out, or at any speed? If it’s only when standing still, is it noticable at any certain engine RPM or at all RPM?
You might check for a heat shield rattle on the exhaust.
Single overhead cam or dual overhead cam?
What do I get if I tell you what the noise is?
~Michael
“Single overhead cam or dual overhead cam?”
I think you meant overhead valve or overhead cam 
If the noise sounds like chirping, and the noise is coming from the drivers side of the engine, and its a Vulcan engine, Then its most likely the CMP Synchronizer
Americar:
Thank you for correcting my mistake. Just getting over the flu and my head is still not right. If it is the overhead valve I would suspect the cam sensor housing. The easiest way I have found to check it is to press sideways on it while the engine is running. This usually causes it to get louder or stop. Here is a picture of the part.
~Michael
I have noticed that it starts and stops when the AC or heat is turned on and when it starts. Once I start driving the car it seems to go away, probably by third gear or so.