I installed a new radiator about two weeks ago after mine developed a crack in it. The car seemed to be running better since then, although it still ran a bit hotter than i thought it should...Well today on my way to the bank it started to get pretty hot (almost into the red on the gauge) and when I came back out of the bank I had lost some coolant...I couldnt tell where it was coming from so I came back home and let the car cool down and filled the radiator back up with coolant. After I started the car, within a minute or so, it will already starting to overheat again, but I wasnt losing any coolant...I need help here. Any ideas, guys?

 

did you bleed the air out of the system? that could very easily cause quick overheating problems.

 

i know i got most of it out, and it has been almost two weeks since the install and only now is it starting to overheat badly..

 

is your pump pumping? is your thermostat opening?

 

Do both fans still come on when the temp climbs?

 

Did you bleed the system correctly? It's not like other cars, you just don't add coolant to the radiator wit hthe car running until it is full. There are 2 bleed screws--I think that they are on the upper heater hoses. There's two valves you have to open to let the air out of, otherwise you'll air lock the water pump. The highest point in the system is there at those hoses--that's why the bleed screws are there. On other cars all the hoses are below the top of the radiator--that's why the fill up the radiator while the car is running procedure works on other cars.

If you bled the car correctly, you can then test to see if the thermostat is working by running the car for a little while. When the temperature gauge gets around 180 degrees, put your hand on the top large radiator hose. Careful, it could and should be hot. If it's not warm or hot, then the thermostat might not be opening. It could also mean your waterpump is broke.

You said you lost coolant? Is the coolant leaking? If it's leaking out of the car somewhere, is it leaking out of the water pump? If it is leaking out of the water pump, then your water pump is bad.
Fix it soon before it ruins your optispark.