So, I'm driving home from work and my car starts making this sound. It's like a scraping/ mild knocking sound. It seems to be coming from the fan area. I'm going to wait until it cools to dig in further. Any ideas what to look for? The engine starts and runs fine, no noticeable loss of power. Could it be the alternator or the fan coming loose?

loose/breaking belt?

Can you determine the frequency of the scrape? Is it at about engine RPM, or 1/4th that?

Does it happen under load, or off load, or any info like that?

I'd doubt the fan is coming loose, but the alternator could make a sound like that if failing.

Grab a little video of the engine with the sound.

Here is a sound clip for what it's worth: Sound Clip

sounds like something stuck in the fan to me

I thought so too. I've looked at the fan with a mirror, and felt around and didn't find anything.

There is a spot just under the fan towards the rear where you can't see and you can't feel with your fingers.. I had the dropsies once with the engine tin screws one day, pain to get out..

I found the culprit. I took the alternator off and started the car, noise was gone. Turning it by hand it sounds pretty gritty. Easy and cheap fix.

Thanks peoples.