I had my radiator re- cored for my '51 3100 and installed it along with new water pump,termostat, belt and hoses. I started it up and let it run. after about 10 minutes I noticed a big river of antifreeze flowing from under my vehicle! I then realized that I had put on the old rad cap which is a 0 lbs cap. I think it should be a 4-7 lb cap. I believe the fluid was coming from the overflow tube. Is this most likely the cause of my problem?

Also when I run my truck after I shut it off my battery is completely drained, what would be causing that?

Thanks in advance for you help!