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White smoke/ steam

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  • White smoke/ steam

    Ok back home now and want to dig into another problem. On why week long trip I was getting sooty buildup on my my transom. Which I assumed was unburnt fuel from running problem. Got it fixed now but I noticed a white smoke/steam above 2800 rpm. Is this normal water vapor? Doesnt smell like oil buring...doesnt really smell at all.


    I dont get it at the hose. Temperature is always 160. Oil has no water and not milky. Changed to full exhaust hose and cleaned manifolds and risers about 3 months ago with new gaskets. Never notices till after then. No water leaking outside. How can I inspect the gasket? Or just replace if suspected leak?

    PCM 351W Raw Water cooled carbed,

  • #2
    Look at the plugs on that side. They will tell you if you are burning water.
    1988 26' cuddy
    1975 20' open
    16' Sandpiper
    14' Certified Fiberglass

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    • #3
      Excuse me for my ignorance. What would it looked like? In a car you would smell the "sweet" smell of the coolant and a steamed plug. I pulled 1 and 5 plugs and the looked normal....however I just changed new plugs probably less than 60 days ago. All the old plugs looked worn, but normal wear. That was first plug change and no idea how long they were in. A lot were salt water also....so I would assume if saltwater intrusion were in the plugs they would be pretty bad....is this correct?

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      • #4
        They would look sand blasted or steam cleaned. Even after a couple hours the plug starts getting a brown tint if running normal.
        Atlantic City, NJ
        1982 Cuddy, Rebuilt 351 .060 rings, Edelbrock carb

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        • #5

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          • #6
            Cyl 5-8

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            • #7
              I have smoke from both sides. I don't see really a real clean plug. One is really sooty but seems the rest look decent. Any ideas. Maybe burning oil? No visible leaks at all on risers or manifolds

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              • #8
                The water flow exiting the riser may not be adequate and the water is vaporizing in the hot exhaust. Check the exhaust hose temp when running the boat over 2800, the exhaust will never get hot enough without load.
                tuner
                Shamrock Addict
                Last edited by tuner; 07-21-2020, 08:47 PM.
                Steve
                1998 260 Mackinaw Sea Maxx 5.7 HO TBI 12' Klamath w/ 20hp Tohatsu EFI

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                • #9
                  I do believe that may be it. I toasted the impeller and water pump a couple months ago. Hence redoing all the exhaust hoses and but a rebuilt pump on it with a new impeller. At idle the risers never get above hand warm. Ive never tested at steady running,

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                  • #10
                    My risers blow steam, especially out the port side. Even after changing the risers. It's been like that as long as I can remember, & really hasn't been a problem that I can tell. I know when the riser needs to be replaced when I see restricted water flow when running on the hose.
                    Clint Smith
                    Idaville, Oregon
                    '93 22' Warrior (Walkaround)

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                    • #11
                      Alot has to do with air,water temp and dew point as well.

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                      • #12
                        Some risers have ridges where the hose mounts. It has been a problem in the past that if the hose is not tight to the ridge, water will be blocked. Engine will not overheat necessarily because enough water is circulating and exiting the good riser. Problem is when the hose gets too hot, riser gets hot, water backs up and gets into cylinder via the valves. Clear as mud?
                        1988 26' cuddy
                        1975 20' open
                        16' Sandpiper
                        14' Certified Fiberglass

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                        • #13
                          Water temp was mid 80s or so. I was in the water with engine running(nuetral of course) and felt the exhaust ...it was not extremely hot coming out. You could leave your hands there without burning.

                          I researched some about the ridges on the risers and thought those were the newer "shorter" style? I took out the old steel exhaust pipe and did straight run of hose. Not sure if that would make a difference. My main concern is keeping water out of the engine.

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                          • #14
                            If you chewed up your impeller pieces may have migrated and are restricting flow. Like at the gear oil cooler
                            '78 20ft Cuddy
                            Mercruiser 350 FWC preVortec w/Carb

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                            • #15
                              Have you used a heat gun to confirm temps? You may be able to tell hot or cool spots and sudden changes to indicate restrictions and leaks. If able I would have a helper drive the boat while you go over it.
                              Karen
                              Punxsutawney, Pennsylvania
                              1986 Shamrock H/T with RWC 330 hp PCM, dual hydraulic helm
                              1992 Mako 211CC w/Mercury Optimax 175
                              3 other smaller OB boats and a trusty old canoe...

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