Yes the coolant will eventually boil with the car sitting still if the fan doesn't work. It's a situation similar to what happened at Three Mile Island.

There is a fuse for the fan in the fuse box under the hood. Check that first because it's easy.

The most common cause of fan problems is the switch on the thermostat housing. Unplug that switch and connect a jumper wire between the two pins in the plug on the car end. Now the radiator fan should come on immediately when you turn the key on. You can drive like that until you can get a new switch, and it should stay cool.

If the fan doesn't come on with the switch plug jumpered, unplug the fan itself and connect two wires from the plug leading to the motor to your battery. The polarity doesn't matter much. Be very careful to avoid short circuits. If the fan still doesn't work, you need a new fan motor. If it does, but won't run when plugged into the car, could be the relay in the fuse box under the hood.

 

Start by checking whether fuse 57 (under-hood fuse box) or fuse 17 (under-dash fuse box) is blown.

To directly power the radiator fan, run a wire from the + battery terminal and to the radiator fan motor where the BLK/RED wire is attached. Touching the battery wire to the latter terminal should immediately turn the fan ON. ***Avoid electrical shock (wear a rubber glove) and injury by the moving fan blades.***

 

Its def a leaky headgasket.

 

Definitely not what I want to hear.

 

Does it matter what kind of wire I run?

 

For either my test or that suggested by mk378, try to use a wire gage similar to that of the BLK/RED wire.

 

well if its fine when driving faster but overheats in traffic id say it has something to do with the radiator fan... either its bad, a wire broke, a bad relay, or bad temperature sensor. several posible problem areas. i would jump the fan motor first myself. one side is power and one side is ground wire. i cannt remember which ones which.
you jump it with any type of wire JUST AS LONG as its as large as the stock wiring! dont try using some tiny @ss wire or it will just fry that wire and glow red hot!

 

Might want to replace your radiator cap. A worn spring could be causing coolant boil over in the engine. Also make sure your mix is 50/50. This isn't optimal, but its easy and it's close enough.

 

OK,

So I stripped down an old power cord that was pretty thick and used half of it (since there's a + and -). I ran one half from the + side of the battery and the other I connected to the metal conductor on the plug that corresponded to the Black/Red wire.

When I started the car, nothing happened with the radiator fan. Was I wrong in connecting it to the plug and not directly to the fan? The plug runs straight to the fan. The only reason why I did not go directly to the fan is because the cord is connected on the underside of the fan and it is difficult to get to.

 

I'm not sure exactly what you did. To make sure you are isolating the test to only the motor, unplug it and run your test wires right to the pins in the motor plug. You need a (+) and a (-) wire to have a complete circuit to test it. If you jumper the fan motor to the battery it should start immediately without needing to turn the key on.

It may be simpler to test the fan out of the car, if it turns out to be bad you'll need to remove it anyway. The fan lifts out after taking the two bolts out of the top holding it to the radiator. You may need to remove the top radiator hose and push the A/C lines out of the way (DO NOT disconnect any A/C line connections, the refrigerant will blow out under high pressure. Simply take the bracket loose and push them toward the back of the car.)