Burning smell

I have a slight burning smell coming from under the hood of my 1997 4L OHV V6 explorer with 130K miles. I smell the smell after I park in the garage. If I open the hood while the engine is running, I can faintly see steam/smoke rising up from the front of the engine. I can't tell exactly where it is coming from though. Does anywhere here have a technique to share that they use to pinpoint the location of whatever fluid it is that is leaking and vaporizing when it hits the engine? I don't have anything leaking onto the ground under the truck, so whatever it is isn't leaking very quickly. Oil, transmission fluid, and radiator fluid(which I suspect is the leak) are all normal. The truck has always used a little radiator fluid ever since I've had it. Probably a quart every 10K miles. Thanks.