What I found worked for me was to remove the hose with the bolt in and connect a new piece of hose about a foot long (after I had raised the nose up), then I made a funnel out of an old washing up liquid bottle by cutting off the bottom and then connected this to the free end. I then supported the funnel in the upright position. This meant that when the engine was running air could still escape via the hose and funnel, however it also meant that I wasn't drawing more air back at any point in due to the head of water in the funnel. Just be careful as the coolant in the hose still gets hot. Then when the engine was cold I could tip the water out of the funnel into a bucket remove this assembly and replace the old hose. Hope this makes sense and good luck - Andy