Sand in cooling system

69fastback69fastback Member Posts: 951 ✭✭✭
in Engine Discussions


2003 Captiva 232, 350 Mag/Bravo 3, 420 hours


Winterizing my boat today, when I disconnect the two quick disconnects in the block, I noticed not a lot of water ran out of the port side. Upon inspection, the small hose that runs between the left and right disconnects on the block was stopped up with sand, on the port side only. I blew compressed air in the hose, and haven’t got it cleared yet, but I also blew air into the quick connect fitting into the block, which cleared a blockage and the block drained. I’ve blown air in both sides, and in the 4 blue plug holes, and I can’t see any evidence that there’s any blockage in the engine itself. Do I just clear the small hose and go on?  Obviously the main immediate concern is that water could still be trapped somewhere for winterization, but then the other concern is a overheating problem next season. 


To this point, I’ve had no issues. I ran the engine for probably 20 minutes on the water hose, before I drained it, and it ran a steady 153°, per VVM. 

What’s my course of action here?

thanks in advance
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Comments

  • aero3113aero3113 Member Posts: 9,752 ✭✭✭✭✭
    I found the same issue on my engines last fall (boat was new to me). I just stuck a straight pick into the connectors at the block and water started to flow. I haven’t checked them this season. Temps were fine before I cleared them.
    2008 330EC
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  • 69fastback69fastback Member Posts: 951 ✭✭✭
    Well I haven’t had much luck clearing the hose yet. It’s deeper than a pick so I’m using a zip tie with basically no luck. 
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  • 69fastback69fastback Member Posts: 951 ✭✭✭
    Bailing wire works well. I’m about 8” in and still stopped up. 
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  • 69fastback69fastback Member Posts: 951 ✭✭✭
    So that hose that I’m talking about, that you disconnect to drain the block, where does it go?  I can’t follow it because there’s just no room to see it in this boat. Is it just one hose that runs between the block drains, or do they connect to something else?
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  • aero3113aero3113 Member Posts: 9,752 ✭✭✭✭✭
    I think it’s connected to the water distribution connection (the weird looking bulb on the port lower front of the engine).
    2008 330EC
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  • 69fastback69fastback Member Posts: 951 ✭✭✭
    It is indeed. I have to remove my back seat, but I got the hose off. It’s completely stopped up with sand. I blew through the distribution block and everything seems clear of blockage. Do I replace the hose and just run it?
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  • aero3113aero3113 Member Posts: 9,752 ✭✭✭✭✭
    Yes, I think it will flush out any residual sand. If you bend the tube back and forth, will it help break it up?
    2008 330EC
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  • 69fastback69fastback Member Posts: 951 ✭✭✭
    It’s just 3/8 fuel line. I made a new one. 
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  • randy56randy56 Member Posts: 4,085 ✭✭✭✭✭
    This is 350 mag. MPI water system  
    DIAGRAM Mercruiser 350 Mag Mpi Engine Diagram FULL Version HD Quality Engine Diagram - NEUROREWIRINGPIEROGABRIELLINELLESCUOLEIT
    Boat Name : 

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  • 69fastback69fastback Member Posts: 951 ✭✭✭
    Thanks for the pic. Mine varies slightly from that, but I got it figured out. I ran the engine with the block drains disconnected and flushed a little more sand out, and I just replaced the blocked line. I feel good about it. 
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  • Lake_BumLake_Bum Member Posts: 1,139 ✭✭✭✭
    How in the HECK did all that sand accumulate in there??????  Wow 
    2000 Captiva 232 
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  • captkevincaptkevin Member Posts: 538 ✭✭✭
    Is boat a river boat? Or was is it previously.
    2004 232
    2021 Yamaha Fx svho
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  • 69fastback69fastback Member Posts: 951 ✭✭✭
    Nope. Lake woth sandy beaches. I’m always very cautious to raise the outdrive and never let it touch the ground, and I always coast into the bank. 
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