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  1. #1

    Default "I have a '88 Four Winns w

    "I have a '88 Four Winns with a 5.0 305 GM engine. I was putting across the lake to pull the boat out for the winter when I had the bright idea of going on one last cruise. I putted along for 5-10 minutes (just above idle speed) and smelled something weird. Sadly, my temp gauge crapped out over the summer and I was not aware that the engine was overheating. A few moments later and I was fully aware of the problem when smoke was billowing from the engine. I shut her down. A minute later a strange "plunging" sound occurred. I first thought there might be a water blockage and it became free and "whooshed" out...like plunging a toilet, or like the liquid plummer commercial...so I thought I might be OK...until I turned the key and the starter just "clicked". Well, I was stranded for sure. Boat was towed back. I later learned about Hydro-locking. Sure enough, the two last cylinders were filled with water. The culprit? was a trashed impeller. So no water circulation for a while, overheating, a "whooshing" noise, and a hydrolocked engine. I'd like to try to figure out how the water got into the cylinders...through the head gasket? Cracked block? crack head? Bad manifold? The boat is in my barn for the winter and I'd like to figure this out to see if its beyond economic sense to fix it...or if it's something reasonable. Any takers??"

  2. #2
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
    Posts
    3,727

    Default Did you remove the 2 plugs and

    Did you remove the 2 plugs and pump the water out ?

    If water has sat in there for more then a week that motor is toast.

    Get a new /used motor and drop it in and go.

  3. #3

    Default "Hi. Water was removed. I then

    "Hi. Water was removed. I then squirted Mystery oil in the cylinders, turned it over a few times, and put the plugs back in."

  4. #4
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,142

    Default "Ayuh,... Drain, then press

    "Ayuh,...

    Drain, then pressurize the cooling system with Air.....
    Listen for the Leaks,+ follow the Sound..."
    Any Grease is Better,... Than No grease at All....

  5. #5

    Default Is there a tool I need to pres

    Is there a tool I need to pressurize? Or can I rig something with my compressor? I've seen kits for cars but they have a connector for the radiator. Is there something that connects to a hose? Obviously Im a novice....thanks.

  6. #6
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,142

    Default "Ayuh,... You've got to

    "Ayuh,...

    You've got to isolate the various areas of the cooling system,...
    Plug Hoses, pipe plugs, use Vice-grips, Whatever it takes....
    A Schrader Valve can be found in most any hardware store to introduce the air,...
    Plumb a pressure gauge into it, so you can See what it's doing...
    15psi. is Plenty....Use the regulator on your compressor..."
    Any Grease is Better,... Than No grease at All....

  7. #7

    Default Thanks for the tips. It will b

    Thanks for the tips. It will be a while since its currently -20 degrees outside right now.When it gets a little warmer I'll break into it. Im just praying I dont have a cracked block...that would suck.

  8. #8
    Join Date
    Dec 2008
    Location
    Fort Walton Beach, Florida, USA
    Posts
    89

    Default The water could have been draw

    The water could have been drawn in by condensing steam. When you overheated you filled the the exhaust system with steam. When it cooled below 212 degrees the steam went back to water and would create a strong vacuum pulling lake water right up and into the engine. I would put compressed air into cylinders through spark plug holes with the valves closed and check for leaks. A small amount of air will go past the rings and come out crankcase breather. Leakage into another cylinder indicates head gasket. Into water jacket means head gasket or cracked head. Small block chevys crack heads fairly easily. Cracked block is extremely rare from over heating. Intake valves can warp from overheating also. Leakage would come out carb. Remember valves need be closed. Piston top center firing stroke or loosen rockers. Air will push piton to bottom if it is not dead center and valves will be slightly open at bottom dead center.

  9. #9

    Default "Thanks James! I appreciate yo

    "Thanks James! I appreciate your insight. Im also curious how water would have entered opposite cylinders equally. Is it ironic or obvious that when the lake water re-entered it affected both heads in the same way simultaneously? Did the water get sucked through the exhaust and was equally spilled through both risers, through the manifolds and then the head??"

  10. #10
    Join Date
    Dec 2008
    Location
    Fort Walton Beach, Florida, USA
    Posts
    89

    Default If the exhaust system was full

    If the exhaust system was full of steam it would fill equally with water. Even if the water was sucked in from the lake you could still have done damage to the heads or head gaskets. The plunging sound you heard was water boiling in your engine.

  11. #11
    Join Date
    May 2007
    Location
    Kawarthas
    Posts
    3,224

    Default "when exhaust manifolds fail,

    "when exhaust manifolds fail, the water always ends up in the 2 rear cylinders because of the way the rear of the boat sits lower in the water... especially with the rear riser style manifolds on omc's"
    Factory Manual Best, Seloc 2nd best, Clymer if you're desperate.

  12. #12

    Default "Hy Stat- Do you think then t

    "Hy Stat-
    Do you think then that cool lake water entered through the exhaust, cracked the manifolds, and seeped into the cylinders? It was a very windy day (white caps) and when I shut the motor off, so perhaps the rocking motion contributed to rushing water back through the exhaust...as well as vacuum? The first thing cool water would hit would be the manifolds...so that was my first logical inclination...and it seems that by the time it would hit the heads (or even the block) the cool water would have come up to temp and not been as extreme...??? that's what I hoping for anyway."

  13. #13
    Join Date
    Jun 2009
    Location
    Vancouver, BC, Canada
    Posts
    2

    Default "I have just had exactly the s

    "I have just had exactly the same symptoms with my 4.3L OMC. Found water in the front-right and rear-left cylinders (probably due to crankshaft/piston positions.

    So Removed the engine and stripped her down.

    Found two faint black marks on the inlet manifold gaskets, between the water jacket and the inlets on the middle two cylinders. It seems water entered bypassed into the inlet ports, cylinders and then into the crankshaft. All of which caused the hydrolock

    Is my theory plausible? Could both of the inlet manifold gaskets fail at the same time, If so why both sides at once? If I am right, this could be an inexpensive repair.

    Any comments...."

  14. #14
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
    Posts
    3,727

    Default MR Turner if you really want a

    MR Turner if you really want as many people as possible to read your post you should start your own thread.

    I may have a different theory.

  15. #15
    Join Date
    May 2009
    Location
    Quartzsite, Az, usa
    Posts
    489

    Default "The "new post" "s

    "The "new post" "start a new discussion" button is the only draw back on the best forums I've ever seen.

    It is in the skinny blue bar below the new title page and no where else.
    So to start -get to the main list of titles, pick one and there above the first post will be "Discussions"."

  16. #16

    Default Scott had same problem with my

    Scott had same problem with my 305 pulled on a beach and just the lapping of the waves filled my back two cylinders with water i removed water added a bit of oil and she fired up boat is still running that was 6 years ago But with the overheating of yours the members advice on pressure testing is good

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