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Hi Allen, my name is Jason.
Unfortuantely no, there is nothing you can run through the system other than water. Have you taken the engines temperature manually to confirm it is overheating, and that this isn't just a sensor issue? How hot is the engine getting?
Definitely not, the engine will overheat without the thermostat and pressure control valve installed. The engine should run about 160. 190 or more would be considered to hot. I can't tell the difference from 160 and 190 with my hands, so I rely on an IR temp gun. IR temp guns are pretty short money at harbor freight type places. Can you get your hands on one?