Success story. Like so many CDs owners, my 1995 Johnson 8HP Sailmaster outboard was emitting smoke from the upper exhaust port and choking the engine when I ran with the well cover closed on my 1979 CD25. Many posts on this board have addressed the problem and I employed the following simple and inexpensive cure.
I attached a small bronze pipe (plumbing fixture) with Marine Tex to the Upper Exhause port and let it harden for 24 hours. Then I attached a rubber hose to it, ran it through the bottom and out the back of the boat, close to, but not in peril of getting sliced by the prop. Now there is no more smoke in the cockpit and I can run with the lazarete closed. The hose is rated at a maximum operating temperature of 125 degrees but the exhaust fumes do not seem excessively hot and I see no evidence of melting.
One more tip. I glued broadcast quality foam soundproofing (the kind you see in studios) to the underside of the lazarette cover and it has reduced the noise levels appreciably. So the nosy, smokey older Sailmaster is good for yet another season.
Many thanks to those on this post who have provided guidance. Try it. It works!
movieshow1@aol.com
Success Reducing Engine Exhaust
Moderator: Jim Walsh
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Jon
Re: Success Reducing Engine Exhaust
Bob,
I did the same on my 1996 Johnson(2 cycle), with good results. I agree with your analysis of the upper exhaust temperature - it seems quite cool. Maybe it has something to do with the large amount of water that comes out with the exhaust. I actually used a GRN (glass reinforced nylon) female threaded elbow held in place by Marine Tex. I used simple plastic hose below that. I do get a bit of exhaust in the well now and then, but not nearly as much as before. I can motor with the cover down most of the time now.
Cheers,
Jon
CD25 Sovereign
I did the same on my 1996 Johnson(2 cycle), with good results. I agree with your analysis of the upper exhaust temperature - it seems quite cool. Maybe it has something to do with the large amount of water that comes out with the exhaust. I actually used a GRN (glass reinforced nylon) female threaded elbow held in place by Marine Tex. I used simple plastic hose below that. I do get a bit of exhaust in the well now and then, but not nearly as much as before. I can motor with the cover down most of the time now.
Cheers,
Jon
CD25 Sovereign