car overheats! please help!

[GuSpeed]

Okay my car was overheating the other day and I made it home. So the following morning I check the coolant and it needed some coolant. The let the air out the radiator with the bleed valve. But now my coolant in the reservior keeps on going low. And I can't see any leaks. What is going on?

[1991S13]

Are you filling the reservoir or the radiator?

If you are putting coolant into the reservoir and it keeps getting lower it may just be being sucked out into the cooling system. Keep filling it up, and eventually it should level off.

[574-240sx]

Is your reservior cracked. The plastic gets brittle over time and cracks. Is the car still overheating?

[GuSpeed]

yeah but the car started overheating one day, and it turns out that it was low on coolant. How did this get to this in the first place? Coolant don't disappear right?

[rico05]

How quickly after start up (from COLD) does it overheat? If it happens really fast (like within 10 minutes) OR if there is a sweet smell accompanied with a white haze to your exhaust, you have a headgasket problem.

Check all of your coolant lines. Even a tiny hole can leak a lot.

[GuSpeed]

well now i found out that the coolant is actually leaking out of the coolant reservior. It's cracked. But now how does that cause the radiator to overheat? After there's no more coolant in the reservior does it suck air in the radiator therefore causing build up of air making the temperature flucuate?

I need an answer thanks.

[rico05]

If it overflows into the reservouir, and you are driving around corners (like I am sure you do every day) the magic of centrifical force will pull the fluid to the sides of the reservouir, and out of the crack/hole. When this happens enough, you run low, and the car overheats.

FYI: You would need to do this for weeks on end to dump enough coolant to get a serious overheat. Mine does the exact smae thing, and I have to add about 1/4 cup of coolant to just top it off every week or so.

[GuSpeed]

thanks, that makes sense.