I have had trouble with foam in the cooling system that at times comes out from the radiator cap. It an open cooling system, the engine has good compression, the radiator core and bottom tank are new, the water pump is in good condition and has good packing, there are no leaks in the hoses or elsewhere, no water in the oil, and no oil in the radiator. I took the antifreeze out but did not flush out the system, and replaced it with water and a can of standard anti rust and water pump lube. This did not fix the problem, there was still foam. Has anyone else had this problem or can suggest a fix? I am currently thinking of trying No-Rosion and start with their flush product. Any thoughts or ideas would be appreciated.