Radiator overflow leaking

fix the leak and flush heater core with a water hose,then bleed coolant system. if not bled proper coolant wont circulate .

if thermostat is new and not in backward?
then its bad head gasket
there are 2 tools to find this.
1: Rad leak down test tool
2: and the rad cap, green/blue dye test for exhuast

http://www.fixkick.com/Combustion%20Leak%20Test%20Kit.jpg

sold at napa.
. PN.700-1006

The overflow tank won't cause it to overheat. If you have added radiator stop leak just replace the radiator is stopped up.

There are 2 tanks on a radiator. One on top and one at the bottom. They are what seal the top and bottom of the radiator core. You will also find an overflow tank connected by a small hose near the radiator cap that connects to the overflow tank. The overflow tank is where you top up the coolant. One some coolant system, the overflow tank is pressurised and the "radiator" pressure cap is on the overflow tank, on others the radiator pressure cap is on the radiator and the overflow tank is unpressurised.

Do a Compression Test on the Engine and see if you have a Blown Head Gasket. Chances are that is what is causing the Overflow... Exhaust Pressure is getting into the Cooling system

you may need to replace the thermostat or the water pump to solve the overheating issue.
The leak in the overflow was NOT the cause of over heating.
You do have a radiator cap. It is the one on top of the overflow.

The radiator drain petcock is on the bottom of the radiator near one of the corner edges.
(Some face engine, others face the grille)
If for some reason you still can not find it, you can always pull the lower radiator hose (make sure water/engine is cold)

once you flush/fill the system, use a 50/50 mix of water and the proper antifreeze. (older cars use green, newer use orange)

If you are unsure, just ask the guys at the auto parts place which one you need and note that they sell an orange color that can be safely used in old and new cars and it can also be mixed with any color of fluid.

After you have the system filled, start the engine and remove the fill cap.... let it run and watch for air to rise out from the opening. (Some coolant/water may overflow, but you need to watch for any air bubbles coming out)

Once you don't see any air trying to escape, put the cap on tight and you should be good to go,

Another cause for overheating is air trapped in the system.

I hope this helps.

the cap is on the 'overflow bucket' near the fender well. Those radiators have plastic tanks on the sides and they will crack over time. Many won't leak until the car is warmed up and the plastic expands, opening the crack.

For radiator replacement procedure and radiator problem troubleshooting. I suggest you to click the link below and follow the detailed procedure :-----

Why Transmission fluid leaks near radiator?

http://repairhelpcenter.blogspot.in/2012/02/transmission-fluid-leaks-near-radiator.html

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Transmission fluid leaking?

http://technoanswers.blogspot.in/2012/02/ford-windstar-transmission-fluid.html

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How to replace Radiator?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-radiator-on-audi-and-vw.html

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HOW TO REPLACE AN UPPER RADIATOR HOSE

http://schematicsdiagram.blogspot.com/2011/07/how-to-replace-upper-radiator-hose.html

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HOW TO REPLACE A LOWER RADIATOR HOSE

http://schematicsdiagram.blogspot.com/2011/07/how-to-replace-lower-radiator-hose.html

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How to replace Radiator on Car models?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-radiator-on-acura-car.html

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How to flush cars radiator?

http://repairhelpcenter.blogspot.com/2011/11/how-to-flush-cars-radiator.html

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HOW TO PRESSURE TEST A RADIATOR AND CAP

http://schematicsdiagram.blogspot.com/2011/07/how-to-pressure-test-radiator-and-cap.html

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HOW TO REPLACE A RADIATOR

http://schematicsdiagram.blogspot.com/2011/07/how-to-replace-radiator.html
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HOW TO REPLACE A RADIATOR SUPPORT

http://schematicsdiagram.blogspot.com/2011/07/how-to-replace-radiator-support.html

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This details will help.

Thanks.

Your local auto parts store has a coolant flush liquid that youo run through your radiator. Be very cautious though. If there is any stop leak or anything it will not only clean it out, it will open the leaks again.

That should be the hose and pipes that feed or return coolant from the heater core thru the firewall.