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Exhaust smell

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  1. #1
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    footbrake's Avatar
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    Home Port : Tonawanda,NY
    1983 Chris Craft 251 Catalina
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    Default Exhaust smell

    On my Chris Craft Catalina there is always that station wagon effect, where the exhaust rolls onto the rear deck as you're going.

    I'm going to put some elbows on the exhaust and have them right below the waterline. I/O's are below the water so what would it hurt to have my exhaust exit just below the surface? Any negatives I'd like to hear. Thanks-Russ

  2. #2
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    Cap'n Ray's Avatar
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    You stand the possibility of creating too much back pressure on the engine(s). Best you can do is make sure no windows/ doors are open on the back of the boat. Alternatively, if you have hatches at the bow, you can open them and the back doors/ windows so your motion foreword forces air through the boat and out the back- eliminated the station wagon effect. I've had similar issues on both of our carvers (3396 and 3207), and a couple express cruisers.

  3. #3
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    Cap'n Ray is right, every mechanic I have ever mentioned this too says its a backpressure issue, yet they can't explain any more than that. It frustrates me because many of the newer boats do exhaust below waterline or even out the bottom. I do know that if your boat ever "diesels" in a scenario like that it can suck water back into the cylinder.

    I have the same issue and I have found that I have to increase speed a bit. I had a very bad experience with CO in the same scenario.
    ~ on the hook ~

  4. #4
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    I think I 98% fixed my problem. I went to home depot and bought some 2" 90deg. PVC. I bought 2 metal unions, one for each side and clamped one end to the exhaust port and fitted the PVC elbow into the exit end. I then cut 2 pieces of straight 2" PVC,3" long and slid it into the elbow to extend it just past the side of he boat. So far I have eliminated all but a slight trace of my exhaust smell. I'll try to get some pictures. It works great

  5. #5
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    Here are a couple pics of what I did
    Attached Thumbnails img_0002_6.jpg   img_0001_6.jpg  
    Cap'n Ray likes this.

  6. #6
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    that should help, I know the next time I see one of those newer boats on a lift I will have to spend some time looking them over, I know that if you have the proper design (a venturi) that while moving you wouldn't have a back pressure issue, so that must be what the newer systems use, now sitting still would be an issue, i'm tempted to do that with my generator.
    ~ on the hook ~

  7. #7
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    I have them painted the same color blue that's on the lower stripe and you can't even notice the exhaust turn-outs now,

  8. #8
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    I'll be interested to see how they hold up, I would expect they should work fine. You may have a patent in the making....lol
    ~ on the hook ~

  9. #9
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    I did try them turned down just below the water, but they made such splashing and water everywhere it was stupid

  10. #10
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    yeah with them turned down you take a chance of them siphoning water back into the system if the engine ever diesels, I think you have it the best way.
    ~ on the hook ~

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