I have a 98 Honda Accord. I replace the radiator and cooling fan, now they come on as soon the ignition is turned on and 30 seconds later the heat gauge goes to high.I am wondering if I have a grounding problem.
The heat up is probably due to an air pocket inside the cooling system on the engine side. You may try parking the car on an incline with the front pointing uphill, then see if you can add more coolant. You can also see if there is a coolant bleed valve as @Lathejockey81 suggests.