:20 second video -- http://tinypic.com/r/m7glxk/8

My 2003 Nissan Maxima has this loud noise that seems to come and go. It's a rattling noise and I plan on taking it to my mechanic next weekend because they're closed now, but any ideas what it could be ?

 

Fried

 

check the oil in the engine. it sounds like the engine is ready to seize. you might need a new engine, sorry bud

 

if you want you can try pulling your drive belts off and spinning the pulleys by hand to see if ones bad, and while the belts off start the engine to see if the noise is internal

doesnt necessarily sound like the engines going to seize, mine made a horrible noise that sounded like the engine was done but it ended up being a bad AC compressor. check the oil level to make sure though

 

per his video the noise is louder on the right side then the left side, AC compressor noise is not even close to the sound on the video, but hell I'm not a mechanic, i could be wrong...

 

That can't be coming from your engine. I don't believe it.
Take off all the plastic does it do it with the a/c on only? fan on?
Take the belts off.

 

no way to properly tell from a video