Quote Originally Posted by rspears View Post
One fitting on the tank bottom and a vented cap will let coolant overflow into the tank, and then be sucked back into the radiator as it cools provided you have the right cap on the radiator to allow back flow. However, if the tank gets full the vent is not going to support overflow. As long as you keep the cold fluid level low in the tank you should be OK, but if you want to be sure add a second fitting with a standpipe in the tank so that anything above the standpipe gets blown out.
Explain what you mean by the right cap on radiator. Are you talking pressure or a small rubber hose coming off the neck where cap goes on?