Other possibility can be loose radiator cap or worn out radiator cap.Check and replace the radiator cap.If the cap is already replaced or its checked ok.
Then, It can be blown head gasket issue.Try this test to confirm its head gasket:--
Try stopping on a steep incline--does the heater stay warm? If yes, what you have is an air bubble that hangs at the heater hose until pressure from the water pump blows thru it as the engine speeds up. Park on an incline, open the radiator cap, run the engine until the thermostat is open, turn the heater on, crack open any/all bleed ports to release any trapped air, and fill the radiator to the neck. Wait until the level stops dropping and make sure bubbles don't continue to come up. If they do, you may have a blown head gasket that will keep forming these bubbles until you change the gasket. But if head gasket is checked ok and its not forming air in system, then in that case its faulty radiator.check the both hoses are they both getting hot.Actually they should, if one is hot and another is cold then its thermostat or radiator issue.
To Order car parts online:--To get heavy discount on car parts .Click this link below:----
http://technoanswers.blogspot.com/2011/05/from-where-to-order-car-parts-online.html
For car error code diagnosis click the link below:---
http://www.automd.com/diagnose/?amdcid=apwldrbrd1
Car no start:--
http://technoanswers.blogspot.com/2011/05/car-will-turn-over-but-will-not-start.html
