greetings to the forum, I have a bavaria 36 with a volvo md2030 and I have observed that there are two aft tubes that I assume are to ventilate the engine cabin with air, one of the tubes has an engine that I think is the tube that extracts air of the engine and the other I think is the air intake tube of the engine. However when I start the engine and put my hand on the stern tube outlets I don't get any air movement. If my observations are correct, the questions I have are; When is the exhaust fan activated? What mechanism activates it? How can i check that it works?
I have a Bavaria 36 2000 with an MD2030 and I have two pipes feeding the engine bay for air intake only and no fan to extract. If one of your pipes has an extract fan I would suggest there is a risk of not enough air supply to the engine. If there is an extract I doubt it was installed new.
Usually diesel engines on our boats don't need separate exhaust ventilation!
The engine cabinet usually get their ventilation by an air intake into the cabinet and the outgoing air stream is maintained by the combustion air of the engine itself.