Out of the blue, the wife's Elantra started overheating. Can't find any apparent leaks. Pulled the thermostat and reconnected. Filled reservoir to normal level, and that didn't work, and the reservoir level remained unchanged. No oil in coolant, so I don't believe it's the head gasket. The only thing I can think of is there's a blockage, because both fans are operating normally, or it's the cap itself. Anyone with experience out there with similar problem? Thanks, Sweaton