85 Chevy 350 Conversion Van Overheats):

You need to find a qualified mechanic and have it evaluated. Letting a back yard mechanic have at it was your first mistake. Overheating could be any number of things. Bad thermostat, collapsed water hose, bad motor, plugged radiator, improper water antifreeze mixture, bad radiator cap are just a few of the possibilities. Bottom line, either fork over the money to a certified mechanic to get it fixed or dump it, accept the loss as a learning experience and move on to something a little more modern.