So recently I flushed my radiator and block on my 2000 TA after an overheating issue. I filled it back up, now I noticed that after it runs for awhile at operating temperature, when I shut it off I can hear bubbling/boiling in the radiator and then about 20 seconds later, coolant starts to pour out of the top of the reservoir tank filler neck.

What would cause this????

The car isn't running hot, I got one gallon of coolant and approximately 1.5 gallons of water in her.

Would the ratio be too low causing the water to boil?

Would it being too full cause it to run out the filler neck after shut down??

Just a little stumped on this...

 

You have air in the cooling system. You have to bleed it out.

Do this:

**Bleeding the system of air:
Take the radiator cap off when its COLD, top it off, start it up and let it idle, and let it warm up till the t-stat opens. I rapidly squeeze the upper and lower radiator hose like 20 times each while its warming up to help move any air bubbles through the system and by the t-stat on the engine side. When the t-stat opens you’ll see the level drop as you squeeze the hoses, its sucking the coolant through the system. You will also see the coolant start to flow in the radiator fill neck, once it starts to flow the level should drop down a lot, IMMEDIATELY top it off with coolant/water. Then the flow will stop when the t-stat closes. Wait one more time for the t-stat to open again and start to flow, if it drops down again top it off again. Do it a 3rd time if you want to make sure. When the level does NOT drop down when the t-stat opens and coolant is flowing....you're system is free of air bubbles. I always squeeze the upper hose during the whole process to keep any air bubbles moving through. Always works like a charm. Just keep checking your temp gauge until the t-stat opens for the first time to make sure it’s not sitting there overheating from a trapped bubble. May take 10-15 minutes for the t-stat to open the first time.
If you do start to get hot while sitting there and the t-stat will not open…..you have a good sized air bubble on the engine side of the t-stat. Shut the engine off and rapidly squeeze the upper and lower radiator hoses again. Then start the engine again and see if the t-stat will open. Sometimes you just have to work those hoses to move the air through. Even after it seems topped off after a couple cycles…check it the next time you have a cold engine…top off if needed.

.

 

Sounds like you have an air pocket in your cooling system, the air pocket is what is causing the car to boil over. Since you have alredy been driving it, the air pocket will prob. just work its way out. Just keep a check on the coolant level when cold in the radiator and recovery tank and run the car with the heat on for a couple days.

 

I'd rather bleed the system before driving it around a few more days and loosing more coolant after every shut down, even if its less and less til all the air is out. Stuff isnt cheap.

I'll probably replace my cap too, just to be on the safe side. Is a cap from autozone reliable, or should I just go with a replacement GM one?

 

I've had a Stant cap for like 6 years, just as good as factory.

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Could be a lot of things. If you take off the radiator cap after the car cools down, what do you see?

BTW... It's definitely not "boiling."