On my Escort 1600 (Zetec-E, year of 2000), between the air cleaner housing and the radiator (just inboard of the rear of the headlamp housing) is a black vertical tube, about half an inch in diameter, blanked off with a black screw cap which has the word Viking embossed on it. Below the cap is a steel fitting that looks a bit like a union of some sort. The tube seems to lead to a reservoir behind the radiator but it's difficult to see as there's so much clobber in the way! As the Haynes manual doesn't identify this tube it in the engine bay photographs and doesn't seem to mention it in the text, I assume the tube is redundant. But what is it?

a photo would be good.

[quote name='mintalkin' post='8745' date='Dec 23 2008, 11:28 AM']a photo would be good.[/quote]
I did try to upload a photo with my original question but clearly failed! I've tried again in this reply. I can't see it in the "preview post" but I'll "add reply" and see what happens.

it looks like an ac top up point.