I think that ojo1 nailed it, I suggest checking if the cap has the rubber seal at all, does it feel loose?

Oh my God, is that the factory radiator hose? looks like it...Nothing wrong, it amazes me that some of our rigs still wear factory parts, like I got the factory rear wiper blade that came with it, and the factory muffler, and the spare tire still intact, and and and, oh I was the first one to use the hyd. jack and lug nut wrench. The jack wasn't even scratched at the bottom but I got me another lug nut wrench to keep mine intact, might be worth something some day <img src="/forums/images/graemlins/smile.gif" alt="" />