If you didn't use radiator hose lube (or some other water based lubricant) to push the expansion tank onto the bracket, that may be it. However, if that didn't seal, I would think you'd lose all of your coolant and overheat in a few miles. I would jack the front of the car up and crawl under it with the engine running and just meditate for a few hours. You'll find out where it's leaking. Just make sure you use good jack stands.
“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.”
Originally Posted by Mike Miller
I just don't know what I'd do with 560 hp that doesn't involve getting arrested.