I replaced the radiator in my car with the Koyo radiator, and got a bit of an overheat once the car was restarted. The weird part is that the engine was warm, but the rad was ice cold. The last time my car was drove it did fine and hasn't had any overheating problems in years. Did I not refill the system correctly? Should I have put coolant/water in the radiator, then tried to bleed the system? I also replaced the rad cap with the greddy cap, so I am thinking of swapping those back to stock to see if that may solve anything. Any ideas? Thanks.

 

When replacing the radiator, you need to bleed the coolant system. By "overheat," do you mean that your temp. gauge was moving past the 9 o'clock position, or do you mean that your low coolant level sensor went off?

 

If I were you I would burp the system again. Change the radiator cap back and see if tis made any difference.

If the radiator is properly burped, then maybe your thermostat is stuck, but that would be a long shot.

 

Maybe I should have put that differently. By overheat, I should have said something like, the fact that the temp gauge had gone higher than normal. However, I don't think that any level low light had come on. I do believe that there was no coolant in the radiator itself, I think all of it was in the block. Anyways, thanks for the ideas. I am about to go back out and work on it some more.