Not sure what you are talking about. It sounds like two things. Does the engine need to breath? Yes, the 85 golf has a breather hose tied into the intake. One option would be to run the breather into a remote catch tank and plug the inlet where the breather connected to the intake system.

Oil cooler hose? The 85 golf would have had a sandwich oil cooler/ preheater. The oil passages are internal. You need to have coolant circulating through it for it to be affective. They were tied into the engine cooling bypass system. Blocking off one of the hoses rubber hoses should not cause a breather hose to pop off the valve cover, but would deminish any cooling affect.

Perhaps a picture?