I have a fairly new looks like a 4 core radiator with 190 thermostat and an 18 inch flex fan no shroud with a good cap also have a 12 inch electiric fan that doesn't seem to help much. I switched to the hotter plugs because it seemed to run better. That was back in the winter. Do you think that having no shroud could cause this kind of severe overheating with a supplemental fan.