04 Elantra Overheating after Rad replaced
 

So the whole thing started with a call from my girlfriend sayimg that there was green fluid coming from the car, anti-freeze of course. She wasn't far from home and just came back. The weather was bad at the time so it was a day or two before I got a chance to look at it.

The first thing I did was take the cap of the radiator and found it to be empty. I then poured in some anti-freeze and it came right out the bottom of the car. I couldn't tell exactly where the anti-freeze was leaking other than it was the left side of the radiator.

I got a new radiator and did the swap, everything went fine. No leaks when I filled the new radiator. Took it for a quick drive around the block, temp was good and still no leaks.

The day after I replaced the radiator my GF took the car to run some errands and said she had trouble with the temp getting high and had to shut the car off twice to let it cool down.

My first though is a bad thermostat staying closed. I'm really hoping it's not a blown head gasket. I haven't had a chance to do anything other than make sure there is still anti-freeze in there. The radiator is still filled which gives me hope that it's not the head gasket. I think I'm just starting to ramble at this point.

Has anyone had an experience with a bad thermostat causing the radiator to leak?

It could be a stuck thermostat
Or it could be a bad water pump

Replace the thermostat (DIY) should be a cheap fix
Then look at the coolant as it passes the radiator cap
Check for movement at operating temp.