Hey guys I'm needing a little advice if you can. I'm no mechanic. I have a 94 g20 van I work out of and when I bought it I had shop put new radiator and new starter cylinoid etc.... Just recently it ran hot so i pulled over checked fluids and radiator is dry and reserve tank. I filled up and it ran fine and I just checked it and it's empty again. What could be the problem. Any suggestions appreciated