I've had some cooling system problems.
I'll be driving and then BEEEEEEEEEEEEEEEEEEEEEE
Coolant light comes on and so I pull over, turn on the heater and fans and let the car cool down.
Check coolant, NOTHING!

Anyways, I know that much is not normal.
I figured it was the pressure cap that could the the culprit so I replaced it.

This is my question though.
If I have both filler and AST cap off, and turn on the car, should the coolant slowly rise and overflow?
I get no air bubbles when the car is on, but the coolant level just rises slowly.
I'm thinking this is normal as the coolant system warms up and pressurizes but I'm not sure.

Can anyone answer this?
Thanks.

 

The buzzer you hear does not mean you are overheating. All it means is that your coolant level is low. Look at the filler neck. At the bottom on the front of it is a black wire coming from a sensor. I'm pretty sure that's the coolant level sensor.

Read about burping the cooling system and follow the directions. You should always see coolant up to the level of the filler neck when you open that cap.

 

those symptoms can also be caused by the sensor going bad. check the sensor per the FSM

 

Im pretty sure the sensor is workign, cuz when I checked the coolant I couldn't see anything.
And the temp guage needle was rising when the buzzer went off. I looked under the car and saw coolant coming out of the overflow tank.
My thought (and hope) was that its the AST cap that went bad and couldn't hold the pressure so the coolant was coming out of the AST to the overflow.

I've heard/read people talk about if the water seal is broken, I'd be pushing exhaust gas into the cooling system. I just wasn't sure if the coolant level rising means its being pushed out.
I also know that the cooling system pressurizes when it warms up so I wasn't sure if this was normal or not.

 

Also make sure you don't have a pressure cap on the filler neck. It is just a cap with a gasket. I had a similar problem to what you describe and the wrong cap turned out to be my problem.

 

that's odd since I have 2 pressure caps and my car never loses coolant or overheats....?

 

Yeah, I'm sure I've got the right cap at the right place
I just replaced the AST cap. (14 bucks)
Hopefully it will help things. (Scared to drive it now! after what happened before.)