Sea Sled madness. It’s in my brain.

Discussion in 'Fiberglass and Composite Boat Building' started by DogCavalry, Nov 11, 2019.

  1. baeckmo
    Joined: Jun 2009
    Posts: 1,671
    Likes: 678, Points: 113, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    The difference between 4000 rpm in neutral and 4000 rpm driving the prop is about 100 kW output, and about the double in terms of heat load developed inside the cylinders. The engine certainly "knows" ("feels" might be a better term...) what amount of fuel is processed; it's all proportional to the work done.

    As long as the cooling water inlet is not clogged and the impeller is ok, the cooling pump has no issues with a bollard pull session; propeller flow has no influence.

    Cleaning the plugs should work ok, but there is a risk that there is a "spark trail" burned along the inside insulator surface. If there is misfiring, just stop until you have new plugs available.

    And Fallguy, don't overthink simple things in life....... enjoy instead!
     
    DogCavalry likes this.
  2. fallguy
    Joined: Dec 2016
    Posts: 7,683
    Likes: 1,706, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    I am mostly eager to learn..the engine load and fuel throughput and heat developed, I understand now, thanks. When you said 4000rpms before, I assumed he could just wind them up for awhile in neutral.

    Don't think; just do. Watch the 2nd Top Gun movie..
     
  3. DogCavalry
    Joined: Sep 2019
    Posts: 3,116
    Likes: 1,587, Points: 113
    Location: Vancouver bc

    DogCavalry Senior Member

    Well, more data. Trying to start it before, the flywheel would do one full revolution and stop. With the plugs out it turns freely.

    Plugs 2,4, and 6 just as fouled as the others
     
  4. baeckmo
    Joined: Jun 2009
    Posts: 1,671
    Likes: 678, Points: 113, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    Battery low/bad (=high ohm) connections.
     
  5. DogCavalry
    Joined: Sep 2019
    Posts: 3,116
    Likes: 1,587, Points: 113
    Location: Vancouver bc

    DogCavalry Senior Member

    I was concerned about hydrolock.

    Plug number 2 looked like droplets of condensation on it. Number 2 cylinder puffed out a tiny bit of mist when I cranked it.
     
  6. DogCavalry
    Joined: Sep 2019
    Posts: 3,116
    Likes: 1,587, Points: 113
    Location: Vancouver bc

    DogCavalry Senior Member

    IMG_20221127_142954824.jpg
    Better, but hardly like new. More torch?
     
  7. baeckmo
    Joined: Jun 2009
    Posts: 1,671
    Likes: 678, Points: 113, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    Hydrolock unlikely, since any water would find its way down to the crankkase or exhaust through the ports. It may very well be water though, sure sign that there still is water in the fuel injection lines. The plugs should be ok for starting, just clean with some denaturated alcohol, and btw, use carburetor alco in the tank as standard procedure to get rid of water (wise to check with the manual if engine is compatible with the stuff, though....).

    Before further running, I think you have to find a way to flush the fuel system all the way to the injectors.
     
    fallguy likes this.
  8. fallguy
    Joined: Dec 2016
    Posts: 7,683
    Likes: 1,706, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Is it not possible to develop some condensation inside 1 of the cylinders if carbon or engine is keeping the exhaust valve open? Seems possible to me..

    I must have read poorly; I never saw that water got in..
     
  9. DogCavalry
    Joined: Sep 2019
    Posts: 3,116
    Likes: 1,587, Points: 113
    Location: Vancouver bc

    DogCavalry Senior Member

    Started instantly! Running better than months too. Misses one about once a minute instead of once a second. I am much pleased... Dinner's on me fellows!!

    New plugs coming. @baeckmo I'll find a way to flush the system
     
  10. fallguy
    Joined: Dec 2016
    Posts: 7,683
    Likes: 1,706, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    You need to consider decarbonizing a bit. I expect @baeckmo will give you the best advice. I just put new plugs and fly around the lake, but you can't, so maybe the tree pull and go through the throttle a bit as well as the run.
     
  11. baeckmo
    Joined: Jun 2009
    Posts: 1,671
    Likes: 678, Points: 113, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    Any ideas about where the water entered?
     
  12. DogCavalry
    Joined: Sep 2019
    Posts: 3,116
    Likes: 1,587, Points: 113
    Location: Vancouver bc

    DogCavalry Senior Member

    Not many. I suppose it's possible that cylinder exhaust valve was open. We've had heavy rain and wide temperature swings lately. Condensation? The droplets were in the range of 0.1mm scattered over the sooty plug. They evaporated with a minute or two.
     
  13. baeckmo
    Joined: Jun 2009
    Posts: 1,671
    Likes: 678, Points: 113, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    No, I'm referring to the water in the fuel. There is no exhaust valve in a two-stroke engine; the droplets on the plug came from the fuel injector, meaning there is still water in the fuel lines. This is why I suggested that you should not spin the engine until you had flushed all the way to the injectors, in order not to risk corrosion in them. The only way for water into the fuel system is via the tank, suction lines and sloppy discipline at the filling station. As long as you don't have a leak via the fuel level sender (my favourite suspect...) or filling cap, it could rain cats and dogs without getting water into the fuel system! Btw, engines with modern high voltage ignition (capacitor discharge and the likes) must not be rotated unless there is an earthed ignition gap (=spark plug) in each ignition cable.

    The first steel component the fuel will see in your system is the secondary filter bowl; that's where the rust comes from. I suggest that you check (and then check again...) what's inside the primary filter; is it really clean fuel? It can be very difficult to distinguish water from the "new" colourless gasoline. The engine ran ok for the initial period, and then ---trouble, which means water in fuel from somewhere "in your jurisdiction"! The debris you found may come from its earlier life, but not the water.
     
    Stofferaus likes this.
  14. DogCavalry
    Joined: Sep 2019
    Posts: 3,116
    Likes: 1,587, Points: 113
    Location: Vancouver bc

    DogCavalry Senior Member

    Hmm. You give me much to think about. The path for the water is unclear. I can see water getting into the big tank, but past the first filter/ separator, then past the second. Admittedly the second had about 0.25 ml water in the bottom, but how did that get past the first? I'll see about flushing those lines before I start it up again.
     

  15. DogCavalry
    Joined: Sep 2019
    Posts: 3,116
    Likes: 1,587, Points: 113
    Location: Vancouver bc

    DogCavalry Senior Member

    @baeckmo , now that we know she's not a lost cause, you had some thoughts on a more suitable prop?
     
Loading...
Similar Threads
  1. Darkzillicon
    Replies:
    145
    Views:
    15,664
  2. Dillusion
    Replies:
    7
    Views:
    1,203
  3. Tungsten
    Replies:
    26
    Views:
    2,811
  4. valvebounce
    Replies:
    3
    Views:
    1,822
  5. Runhammar
    Replies:
    17
    Views:
    1,564
  6. fallguy
    Replies:
    4
    Views:
    1,019
  7. massandspace
    Replies:
    5
    Views:
    2,078
  8. fredrosse
    Replies:
    5
    Views:
    1,401
  9. Tiger51
    Replies:
    15
    Views:
    3,143
  10. cy fishburn
    Replies:
    5
    Views:
    1,956
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.