92 voyager overheating?

I have a 92 Plymouth Voyager, which I just got back from my son. He was driving it in Seattle for awhile, until it overheated. He had a new radiator and new thermostat put in, but it still overheated. I towed it back to my place to see if my daughter and I could get it running. The new radiator he had put in was leaking from a seam around the top. We replaced that with a new radiator. I drove around for about 60 to 70 miles, into town and back. No problem. Today my wife and daughter took it to town and only made it about 2/3 of the way before it started to overheat. Daughter discovered a hole in the coolant reservoir. But I am still not sure what could be the reason for the overheating. I did replace the water pump about three years ago. Does anyone have any idea what I can do to possibly repair this problem?

Have you checked the basics?
Have you replaced the thermostat??
Is it opening at the right temperature
Is it opening at all? (some faulty thermostats never open)
Are the cooling fans working and coming on at the correct temperature?
Have you done a block test . . . could have a bad head gasket
Do you have the correct radiator cap installed?
After replacing the reservoir, do a coolant pressure test and a block test.
Is your belt in good shape (not slipping and/or glazed)?

one test that will help you figure it out and its a pressure check on your radiator. It will put pressure on all components of the cooling system and should find out what is going on with your van. If it doesn’t show a leak on the outside check the piston chambers by taking out sparkplugs after putting pressure on the radiator and crank the engine and see if coolant sprays out of the sparkplug hole. Hope that helps.