Need help!
 

I have a 05 Dmax with about 260k and I cannot drive more than 4 miles without over heating in 46 degree weather. The truck is losing water really bad I can put a gallon of water or more in it before I leave and it's all gone within 10 minutes. There are no leaks anywhere. I have been having an egr code come up but I'm not getting any white smoke out of the exhaust. And there is no water in the oil. Any suggestions? :argh: