[MV6] After about 30km of steam from bonnet (not overheated)

Hi, I just drove about 30km from time to time slightly pressed. Now I turned it off and determined the smoke from the direction of the engine compartment ascends. I immediately looked again at temp. but the fit was fit 90° engine block was also pully “cool” and otherwise I could not find anything further. Engine oil fits. Maybe has an idea on what it can be? Or does anyone have tips for me? He has to come to the TÜV next month can’t last for me that there still big reperatures come… MfG black_head