Rattling under hood/overheating
 

Alright, so I bought a 99 Eclipse RS about a month ago. Before I bought it, I brought it to a shop to get it checked out. They told me the AC Compressor was shot. I brought it back to the dealer, and they fixed it, supposedly. Pretty much since I got it, I've had coolant leaks/problems + overheating(obviously). I've run out of coolant once, and have had to refill it 3 times. I've brought it back to the dealer 3 times now, and all they've done is throw some new hoses and clamps in there. I brought it to the mechanic my dad has been going to for a while, and he said that he was concerned about the head burning the coolant, due to my exhaust smelling somewhat sweet. I mentioned this to the dealer the last time I brought it in, but they said that it was just a hose leak and that they replaced it. When I was driving home from the dealer, I noticed a noise coming from under the hood. Whenever I get between 2.25k - 2.75k RPMs, I hear a rattling. The best I could describe it would be like the sound a fan (like a box fan) makes when it hits the box its enclosed in. Sound like a plastic/metal or metal/metal combination. Anyway, 20 minutes into the ride home, the "service engine soon" light came back on. The smell of burning coolant hasn't gone away yet, and the car has been running a little extra hot.
Does anyone have any ideas/suggestions or guesses as to what is wrong and what I can do about it? I'm planning on bringing it to another shop tomorrow to see what they can do. I have a 2 year warranty on the thing that I can use at any shop, so thats good.
Eclipse RS 2.0 non-turbo
Auto
85k miles

RE: Rattling under hood/overheating
 

i had a similar problem my car was overheating and leaking, i got a new radiator new hoses and a new thermostat my car is fine now.......i didnt have a rattling tho you could also check to see if the right radiator cap is on there b/c it has to be a specific lb hope that helps

RE: Rattling under hood/overheating
 

i'd change the thermostat just b/c it's only like 7 bucks or something but honestly it sounds like a head gasket to me... you can smell it, level keeps going down, if the hoses were changed than that wouldn't be it... it sounds more than anything like a head gasket to me and not to mention our cars are notorious for blowing head gaskets.

RE: Rattling under hood/overheating
 

I agree. Could be the headgasket. A quick check is to look under the oil cap and see if you have any white goop on the bottom of the cap. There are other ways to check. But thats just one quick way.