I finally found a valve that I could use on the little catch tank, but it's $75 + shipping. I could about buy a different tank for that though, but the main reason I bought the one that I did was because it had a site tube on the side of it to see the level in the tank. I called the guy and talked to him about the application and he said it would be perfect for what I was looking for. I'm probably not going to seperate the systems at the moment now that I have installed the fans on my heat exchanger, I'd like to see how they'll work first, but I thought I would post up the site for any one that may be in need of such a valve. It's the Cooling System Pressure Control Valve, pretty cool little gadget. http://www.vaportrailracing.com/pressurecontrol.htm