My Corolla had a strange one yesterday. I drove up into the mountains and the initial road out of town, US 24, has a 7% grade. Pretty steep. Done this drive a thousand times without issue. I pulled into a gas station to get some coffee. Came back out, sat in my car, and immediately heard a bubbling/gurgling sound. First thing I thought was cooling system. Popped the hood and the overflow was to the top and some coolant was blowing out the overflow tube. I put the heater on, started the car, and the level came back down. I continued on my journey and didn't have any other issues except the level in the overflow continues to fluctuate a lot more than it ever has and came close to overflowing again. There is no signs of overheating at all!
So I bought a new radiator cap this morning and will see if that is the issue. If not, I think it's head gasket time.
The only other weird symptom it's had lately is, in the morning when I start it, if I put the heat on, I can hear coolant rushing into the heater core which indicates air is getting in the system. It's done that for 2 years now. I tried burping the system many times with a Lisle funnel, and the air sound always comes back.
So I bought a new radiator cap this morning and will see if that is the issue. If not, I think it's head gasket time.
The only other weird symptom it's had lately is, in the morning when I start it, if I put the heat on, I can hear coolant rushing into the heater core which indicates air is getting in the system. It's done that for 2 years now. I tried burping the system many times with a Lisle funnel, and the air sound always comes back.