Broken drain fitting on a Mercruiser 4.3L I/O October 18, 2015, 07:20:33 pm Friend of mine decided it was time to winterize his boat. His 4.3L has 4 drain points, two brass plugs on the block and two plastic combo elbows and drain plugs under the exhaust manifold. When he went to remove the petcock under the exhaust manifold, it broke off. He then tried to "extract" it himself and broke the elbow! Now I am going to have to remove the exhaust manifold to get what's left of the plastic elbow out of the manifold. I'll snap some pics tomorrow afternoon of this disaster as it's unfolding.