I've still been fighting my coolant/overheating issue. The original overheating started because my coolant got low and there was air in the system and all that mess. I've put newspaper under my car overnight and no coolant leaks out. I do have a small oil leak though. Lately it's gotten worse. I can fill my radiator up before I leave and drive to school (7 miles) and by the time I go to leave school my low coolant light is on again but there are no liquids under my car. Tonight when I parked I heard something boiling so I popped the hood and I could hear the coolant bubbling. It was a pretty constant boiling sound but after about 2-3 minutes it slowed down and sounding like a drip. It seems to be coming from the resivor side. Under the battery somewhere. What does coolant boiling mean? My car didnt overheat on the way home but I defintly heard the coolant boiling.

 

I kind of have the same problem. I am not sure what temp water starts boiling at but I do know that my car does not run hot at all. It stays right at the first mark everytime i drive it. I have no coolant leaks and I checked my coolant bc it started getting progressively warmer over time. My radiator had alot of coolant gone. I think it took almost a whole gallon to fill it back up. I realized that when I did my cam install and I put way more water in there then I did coolant and it must have boiled/evaporated the water away. Hence why my radiator was way low. Apparently the water boiled away and just the coolant remained. Try adding more coolant instead of water and I bet u it goes away. Peace, Dustin.

 

Thing is I am filling it up with coolant. 50/50 Mix anyway

 

Boiling temperature of water or any liquid is dependent on pressure. At 1 atm or 14.7 psi water boils at 212 degrees F, when the pressure increase, so does the boiling point. What maintains the pressure in the system (assuming no leaks) is the radiator cap, if that goes bad and could not maintain pressure then the water in the system would reach its boiling point (remember these cars are designed to work at 200-230 F). Now water in it's gaseous phase is a lousy coolant, so whenever it boils conditions deteriorate fast.

 

Yeah I would check the rad cap first as if it is bleeding off pressure you are essentially dropping the boiling boint of your coolant

If you still see coolant missing and no leaks after the rad cap is replaced do a cooling system pressur etest,, this will tell you whatyou wat to know which is "do I have any internal leaks???"

when I blew a head gasket on mine I was using about 1/2 quart per 75 miles of coolant,, no smoke,, no milkshake in oil as it was just burining off in the cylinder,, cooling system pressure test showed a slow pressure drop and when I went to start it after pressure testng it is hydrolocked because I filled which ever cylinder with coolant due to the test.

 

Mine was doing the same thing, I replaced the radiator cap and it did nothing. I finally realized that when me and my friend replaced my radiator we switched the 2 lines at the top of the radiator. The highest one should go to the reservoir. If you buy a new cap, get a GM one, the Autozone ones suck, it made my problem worse. The cap is definately where I would start. Good luck.