Blow compressed air through the tell tail. Hook up your hose with muffs or flush fitting and see if that helps, you shouldn't have to start it for the hose to get water through it.
There are a lot of ways that you could lose water. If you haven't done a water pump in the last couple years you need to do it and then test again. You should do the kit, sometimes a gasket can wear out and let enough water by to drop the pressure to low.
What kind of motor is it and what year model? Was the overheat at the same time as your no tell tail issue?
Edited by Dawson Hefner (11/16/17 01:42 PM)