Coolant issue

Hi mga master Happy new year, ask ko lng po kung nakakatangal ng dumi un coolant, first time ko maglagay ng coolant sa radiator then suddenly may lumabas na foam sa radiator ko nung chenik ko dumi po.what i did drain ko un tubig pero mron prin konti foam.before nung distilled water lang un nakalagy wala nman ganon issue..ok nman un oil walang mix ng water when i checked the dipstick, hinde rin mausok un kotse and to check the cylinder headgasket hinati ko un 1.5 coke at ginwang imbodo nilagyan ko ng tubig then start hinde nman bumulwak. bago rdiator ko 2 rows

If your radiator is bubbling even without load you may need to look at your cylinder head.