DODGE NEON OVERFLOW BUBBLING!!
I own a 2005 Dodge Neon. In very hot tempertures the coolant reservoir begins to bubble. The temperature gauge rises but has never reached the highest level. I have replaced the thermostat, and the thermostat housing. I also refill the coolant often. I am almost sure coolant is leaking somewhere but I am unable to find the issue.
Bubbling in the recovery tank usually indicates a blown head gasket. Here's a quick check you can do, let the car sit overnight, before you start it make sure you have a clear view of the recovery bottle, start engine and watch for bubbles, if they start within a minute of start up then it is most likely a head gasket. If they don't then you need to have the system pressurized to find the leak.
I am very sorry I did not mention this before. I am almost positive it does not bubble when I am in driving.
It might not after the pressures have equalized. That is why you do it cold, before there is any pressure in the cooling system. If you don't feel comfortable with that test you can take to a shop and have a "block check" and a pressure test, that should eliminate any questions.
its the radiator cap or the headgasket
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