overheating, I'm stumped. Options

[6strngs]

so today, I drive my car home from work. get out of the car and notice a strong coolant smell. I let it cool down for a while, then went out to check it. The radiator was still full with coolant, but the overflow tank was kinda low. so I poured some coolant in (pre-mixed 50/50). anyway, so I go to drive the car again and after a short trip, only a couple miles, I'm hearing this weird whining sound. I glance down and see that the water temp gauge is reading HOT! like, it was all the way into the red! I pull into the closest parking spot and shut off the car. I let it sit for about half an hour and decide to drive it back home. I start the car up, and the temp gauge jumps to 1/2 way. normal. and as I start driving, it starts climbing. it gets to about 3/4 of the way to hot and then very suddenly just drops back down to half. then it stays there the rest of the way home. I pull into my garage, and get to work. I tried my best to track down a leak and decided it appeared to be that the hose that feeds coolant to the throttle body was leaking. so I replaced it. so after a couple hours of work (decided to do some other stuff too since I had everything taken off anyway) I go to drive it again and same thing. the temp gauge reads normal, then it will climb in temperature, then drop back down to normal, then climb again, then normal. anybody have any ideas? thermostat? water pump? malfunctioning sensor and/or gauge?

[6strngs]

Good news! thermostat was replaced. coolant filled to the top with brand new coolant. and everything re-assembled. and now it runs fine without overheating! thanks for all the help guys.

Oh, one other thing. when I was putting my engine covers back on under my car right after I had burped the system, I found a small dribble of coolant on the bottom of my radiator. I wiped it away and more came... did that a couple times. I don't know if it was just the coolant that I spilled leaking down or if it was a leak from the bottom of my radiator. I'm gonna keep an eye on it. I might have to take my radiator in to my welding class and ask my instructor to help me weld it where it's leaking.

This post has been edited by 6strngs: Feb 16, 2007 - 5:28 PM