I have a bmw 318i e46 and she keeps overheating the 2 pipes from the raditor keeps filling with air. any idies

Replace the header tank...common problem with these.....get from dealer, less than 100 quid....also check the cooling fan is working as this causes the tank to split if it is not....not so cheap and complex to repair

Check your radiator for blockage, and have your cylinder block check for blockage. If everything is ok there. it could be the cylinderhead gasket has blown, and need's replacing.