it's to purge air bubbles from the system. to translate the diagram:
????????????????????CAP = Depending on car model to the engine air removal hole or Plug cap
???????????= Filler Plug Cap
?????= Radiator
??????????Radiator cap
?????????Breather Tank
????????Reservoir Tank
????????????????????Radiator hose attachment (sold seperately)
HTH.
????????????????????CAP = Depending on car model to the engine air removal hole or Plug cap
???????????= Filler Plug Cap
?????= Radiator
??????????Radiator cap
?????????Breather Tank
????????Reservoir Tank
????????????????????Radiator hose attachment (sold seperately)
HTH.