General Maintenance & Repairs - Engine rattling?

Quick synopsis:
Driving home from class the other day (90 degree weather here on long island) my car started overheating. Pulled over filled it up with coolant/water and took it home. I ended up having to stop 3 times to let my car cool down. Finally got it home and let it sit over night. Woke up the next day started the car and 15 minutes later it started overheating again. I just replaced the thermostat last summer so I know it can't be that. I ended up checking the oil and I was low so I threw a quart in started it up again and some kind of rattling noise started coming from the top of the engine. Really weird rattling noise, almost sounds like water or something in there. No idea how to diagnose this but if anyone has some idea I'd really appreciate the help.

any smoke ? what color is the oil ? man i hope you not do any serious damage on the engine by runnin git low on oil and over heat, you need pop the hood more often and check on coolant and oil every sunday or so.

No white smoke and oil is perfectly fine. And I normally do I don't know how I missed it. I was only low about a quart, which is still a lot but not unheard of.

No white smoke and oil is perfectly fine. And I normally do I don't know how I missed it. I was only low about a quart, which is still a lot but not unheard of.

low 1 quart is alot ! when the last time you change the oil ? have you find out why you loosing coolant and over heat ? take it to your mechanic to let him look at it. I wont drive much until i find out what problem is before any big damage.