Re: mercruis 140 alpha 1 mystery part in exhaust
Is the piece made of rubber? If so, it is half of your exhaust shutter (flapper). The Merc shutter design is good--it breaks in half and the halves usually blow through. The OMC shutter design usually fails in one piece, and sometimes blocks the exhaust downstream.<br /><br />The shutter is #7 in this diagram. The mount #2 is held in by screws #3 and nuts #4, but in older exhaust elbows the mount #2 was riveted, so you may have to drill out the rivets and replace them with the right screws and nuts.<br />
<br /><br />The shutter is #45 in this diagram.<br />
<br /><br />I will be installing a new shutter in my 1974 Merc 140. I have the manifold, riser and exhaust boot off. You could get access by removing your riser and boot, but you may not be able to get the riser off without pulling the manifold. Separating the riser and manifold can be tough. Don't pry, or you'll crack one of them.<br /><br />A mechanic told me to dab the ends of the new flapper metal rod with silicone, otherwise it will rattle.<br /><br />Good luck.
