djdc

So I've been trying to figure out why my coolant is boiling. Today I added some coolant, started it up, ran pretty good. Heated up good too. So I let it get to temp, then shut it off. I watched the expansion tank, saw 2 or 3 air bubbles come up, but not the boiling I had witnessed, I didn't let it get that hot.

I checked my oil level, it looks good. So I started to take the expansion cap off, it let out some pressure, then I noticed coolant comes in from that top hose, enough to take the tank from the min line to the max line. So i cap it back and let it cool. Then after it has cooled, I take the cap off again to check the mixture (make sure its 50/50) and the coolant drains out of the bottom hose. I don't understand where this coolant is going. It was well below the min line, which is where it was when I started. I don't see any leaks and if that amount of coolant was in the oil, the oil level would be much higher than it is.

Any help or suggestions would be greatley appreciated. Thanks.

TabulaRasa

There is a valve at your heater core that opens only when the heat is turned on. I'm thinking you have some air that needs to be bled out.

tozoM8

If your car is automatic, the coolant can go in the tranny if the radiator is leaking.

djdc

Ya its an auto, I forgot about that. Thanks.

quattro2turbo

do your fans come on? if not, check your fan switch.

samm

Sounds like air in the system. Try bleeding.

rosskuhns

sounds like some air in the system (hopefully)

Remember, if the engine is hot/warm when you take the expansion cap off, the coolant is under pressure and will expand in the tank (fill it up), so you need to check the level when it's cold, and add when it's cold.

Remember: heat expands; cold contracts

I was having some issues previously myself, and the best way to check I found was to mark the level on the coolant tank when stone cold with a sharpie; then check again in a few days again in the morning before starting up.

Ross