Paccar water seperator

[Waterloo]

I don't think they are supposed to stay full during normal operation. I have the Davco unit on mine, when the filter is changed it may have 1/2 inch of fuel showing through the plastic dome, and as the filter ages the fuel level rises. Personally, I just drain the water off periodically and change at every other service. I have never seen mine full other than the time it hit -30 on the thermometer...