I'm getting ready to replace my lower radiator hose and when I was checking where it ran to, I came across this part which I had not noticed before. I've attached a picture so that you may see what I'm asking about. It appears to be a valve of some sort, but nothing is attached to it. I've looked in the FSM, but it doesn't mention anything. What is it and should it be connected to something? My car has been running fine and will probably bypass it unless someone says otherwise.

Thanks for any help!

1978 280Z

Here is another photo.

Hmmmm... Well, I have a '78 and know every square inch of it. I'm stumped. There's not anything in the Factory Service Manual about such a part. I'd say it wasn't Nissan that put it there. But I haven't a clue what it would be.

Oh, wait... Alaska....

Maybe something to heat and circulate radiator water?

I suppose it could be a circulating tank heater, but most tank heaters have a larger electrical connector. I'll pull it apart for a better look.