When I pour coolant into the overflow tank, it takes a little bit, then it pours out from all the way to the top, about a half inch away from the battery. So it is holding most of the water in, just not a little bit. I tryed to taking it out so I can see the crack/leak, but it wouldn't go anywhere. Its as if something is holding one side of it. Yes I did remove the battery and the bolts that hold the battery tray/coolant overflow tank.
After getting under the car and looking at it closely with a good amount of light, it seems the metal around the tank are a little bent, making it more oval than round, so that now the tank is too wide to come out. I was pulling and pushing on it with a lot of force, and it wouldn't come out.. The car has been in an accident, involving the front right side so I am prety sure thats what caused the metal around the tank to bend. I guess that is probably what caused the crack in the tank as well.
It doesn't seem to be affecting how the car cools, but I was reading that a coolant system needs to be completely sealed, and then if it pressurizes the cap on the overflow tank will open up. Am I ok to go? I am not loosing coolant from it as far as I know. Should I cut the overflow tank, and remove it, and then try to buy something else to use in place of it? Thanks

 

Have you found the crack? If so, maybe you can repair the crack with some epoxy or something.

 

I can't visibly see it, but I basically know the area its at. Would Epoxy make a mess? I dont want it getting into the cooling system. Is it easy to work with?

 

Are you trying to pull it from the top? It comes out through the top.

 

Yes, from the top. The metal part around it is what blocks it from coming out. Imagine this. You have a piece of metal around a plastic container. And a strong force pushes the metal in, changing its shape. Now the plastic container is stuck.

 

I patched one once when I was in a bind. I cut off an "extra" piece of plastic from elsewhere on the overflow tank and I then heated up the extra piece as well as the damaged area of the tank with a cig lighter, then smeared it on. I think I then covered it up with some sort of sealant. (I don't remember what kind of sealant, sorry. Your concern over coolant contamination is a valid point.) This was on Mitsubishi, so I'm not sure it there's any "extra" plastic on your tank.

Bottom line is you need to get the thing out first. The body damage must be an issue. I remember mine came out easily.

As far as losing coolant goes. You would be most likely to lose some when the car is hot and the overflow reaches it's highest level.