skiracer8148

my car is a 93 civic ls/vtec,when ever i take my car to vtec it overheats and the fan doesn't kick on and the coolant resevoir overfills.after driving the car for about 10 minutes the temp goes back to normal.its like the thermostat doesnt open but its a brand new oem honda thermostat installed last week.when i drive the car normal it doesnt over heat and the fan works correctly.i burped the system also and still no help.i also have the oem honda del sol vtec radiatior.anyone have any ideas?thanks in advance