Mercruiser 350 MAG injesting seawater? Need help. | FerrariChat

Mercruiser 350 MAG injesting seawater? Need help.

Discussion in 'Motorcycles & Boats' started by 11506apollo, Aug 7, 2015.

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  1. 11506apollo

    11506apollo Formula 3
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    Oct 16, 2008
    2,494
    Tx Co Ca
    #1 11506apollo, Aug 7, 2015
    Last edited by a moderator: Sep 7, 2017
    Hi. my 23' Robalo has regular through the prop exaust (Alpha 1 drive), but also throug-the -transom exaust. The solenoids that actuate the flappers in the ThroughUll dual exaust must have failed during rough seas because exaust was loud during recent fishing trip. Seas were a little rough and after a couple of stops to check somethings on the boat and use binoculars to search for shrimp boats, engine started to loose rpm at 32knots and 3,500 rpm. Stopped boat and killed engine to check. Upon opening engine cover, lots and lots of smoke pouring from engine. and a "crackling" sound as if electrics were on fire. One of the exaust bellows was ruptured and water was slowly pouring into bilge, probably coming from the exaust tips in the transom. So, my theory is that the trough the transom exaust was open of course due to bad solenoids. the two stops in relatively rocky seas made water come into the exaust pipes and possibly down into exaust manifold (valves too?). this caused havoc and thus loss of power and tons of smoke from vaporizing/boiling seawater(?). Exaust pipes on starboard side burned all paint. Port side seems to be fine. I am attaching some pics. My big question is: is engine toast for ingesting seawater? Do you experts agree with my scenario above, as to what happened? Insurance claim filed. Coast guard folks were tremendous in rescuing us. Pics show Coast Guard folks towing us back to shore, starboard Corsa Exaust pipe totally overheated to the point all paint is gone (Port pipe is visible with paint intact..), and vertical exaust riser going to drive damaged and seawater pouring out of it, and finally Rubber flapper at transom damaged by overheating. thanks
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  2. BoulderFCar

    BoulderFCar F1 World Champ
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    #2 BoulderFCar, Aug 9, 2015
    A guess but you may have lost a water pump or had and intake blockage. The motor got really hot. Your bilge vents have melted as an indicator. Was the temp gauge running hot prior? Based on some of the signs it's a good thing the boat didn't catch fire.

    Doesn't look good. The good news is that is an easy engine to repair.
     
  3. zudnic

    zudnic Formula 3

    Nov 13, 2014
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    #3 zudnic, Aug 21, 2015
    Unless you have closed fresh water cooling, you have other problems causing an overheat situation. No closed cooling means the engine pulls water from the drive to circulate and cool the engine. Drive exhaust the water exits the drive. Thru hull exhaust it exits the exhaust. Since you are boating salt water, means sea water is being pumped through your engine to cool it. Sounds like you are not flushing it with fresh water after using in salt. Not doing so will destroy the motor in short order. You'll have corrosion issues in the engine.
     
  4. kylec

    kylec F1 Rookie
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    Orlando
    #4 kylec, Aug 29, 2015
    Bad thermostat or waterpump my guess. The engine should probably be pulled and the bearings on the crank looked at.
    Is it open or closed cooling? Either way, have you been running it on a hose after taking it out?
     

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