The other method...........rubber stopper plug in one hose connection.........hand vacuum pump like Mity Vac used in bleeding brakes. Draw a vacuum on the heater with a stopper in the other hose connection. Pump a vacuum ........should hold a vacuum if there’s no issues with the core.
This method works really well at the swap meet. No water no pressure needed.
Last edited by showkey; 11/10/2020 10:25 PM.
