Diagnose Low Water pressure 5.7L 350

Discussion in 'General Maintenance/Repair Questions' started by Todd320, Oct 26, 2018.

  1. Todd320

    Todd320 Well-Known Member GOLD Sponsor

    Jul 21, 2016
    St. Petersburg, FL
    2007 Sea Ray 320DA
    Twin V-drive 5.7L 350 Horizon
    I have Horizon 5.7L mpi fresh water cooled engines 2007-ish). Received an alarm at 3900 rpm, low water pressure.
    Had to keep that engine at idle the rest of the way home (ran just fine the entire day, last mile in after stopping to enjoy the calm water). I have a mechanic, but I know it could just be a blockage in the strainer if I sucked something up. So, first I’m Climbing under the boat to remove any grass/crap in the intake. Then I’m going to clean the strainer. Then I’m going to replace the water pressure sensor, I have a spare. Anything else relatively simple before I get the mechanic involved? It very well might be a bad water pump, already replaced the port, so starboard is going to go soon.
     
  2. dtfeld

    dtfeld Water Contrails

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    2001
    Axiom 12 MFD
    Cat 3126 V-Drives
    If it only alarmed at 3900, but not idle, probably something sucked up, partially blocking something, likely the strainer.

    I think you're on it. Id look in the strainer first before going overboard, unless looking for a reason for a swim. I'd hold replacing expensive stuff until the known choke points are clear.
     
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  3. Southern Cross

    Southern Cross Member

    65
    Jul 29, 2013
    Alexandria, VA
    2005 320DA
    Twin 350 MPI, V Drives
    You are on the right track. I would check the strainer first before going over the side to check the intake. If you don’t want to get in the water, close the seacock, remove the hose from the seacock, and re-open and close it quickly. If water shoots through the seacock like a high pressure hose then your intake is clear. If not, it might be time for a swim...
     
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  4. Todd320

    Todd320 Well-Known Member GOLD Sponsor

    Jul 21, 2016
    St. Petersburg, FL
    2007 Sea Ray 320DA
    Twin V-drive 5.7L 350 Horizon
    Boat will be on the rack when I get there, that’s why I was going check there first. And last time I was there I was searching for where the transducers are located, and I noticed a small amount of grass in the intake, but did not have any tool to get it out (I’m assuming the grill just comes off with a screw driver?)
    Appreciate the help! Thanks!!
     
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  5. Todd320

    Todd320 Well-Known Member GOLD Sponsor

    Jul 21, 2016
    St. Petersburg, FL
    2007 Sea Ray 320DA
    Twin V-drive 5.7L 350 Horizon
    Well, sort of like I expected. Little bit of grass in the intake, nothing major, nothing in the strainer. Replaced water pressure sensor just in case. Cranked engine, belts, pump, did not look right, I ran back and turned off the engine. Not sure exactly what I saw, but pretty sure the belt was not spinning. So, just like my port engine, the alternator or something is locked up and so the tech is called. Hopefully less than 2 boat dollars!
     
  6. Craig

    Craig Well-Known Member

    835
    Feb 8, 2007
    Maryland
    2006 320 Sundancer
    twin 350 Horizon V drives
    As much as I hate it. I generally do things in tandem because I figure its going to happen on the other engine too.
     
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  7. Todd320

    Todd320 Well-Known Member GOLD Sponsor

    Jul 21, 2016
    St. Petersburg, FL
    2007 Sea Ray 320DA
    Twin V-drive 5.7L 350 Horizon
    I tried, but was unsuccessful in getting both done.
     
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  8. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    If you want try something yourself, take the belt off and spin every accessory pulley by hand and locate the culprit. If everything spins, start it up again and take a better look at things. If you're not comfortable with replacing any of the accessories yourself, then there's probably no reason to do that as it won't save any time for your mechanic - he'll check all that out, anyways.
     
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  9. Todd320

    Todd320 Well-Known Member GOLD Sponsor

    Jul 21, 2016
    St. Petersburg, FL
    2007 Sea Ray 320DA
    Twin V-drive 5.7L 350 Horizon
    I’d like to think I could do it, but I’m just so freaking slow when I do work like this.
     
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  10. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    No worries - it's good to keep food on your mechanic's table! :)

    Besides, with v-drives, it's done a little bit more by "feel" since the engines are backwards. Which makes it a little more challenging the first few times you do it.
     
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  11. Curtis

    Curtis Member

    63
    Feb 6, 2013
    San Antonio, Texas
    320 Sundancer 2004
    Previous 280 Sundancer
    Twin 8.1 (496 Mags) w Bravo III drives
    Where is the water pressure sensor and what does it look like?
     
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  12. Craig

    Craig Well-Known Member

    835
    Feb 8, 2007
    Maryland
    2006 320 Sundancer
    twin 350 Horizon V drives
    shopping.png B352CF9F-43EA-4927-9A78-970E5CB8DC2D.jpg
     
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  13. Curtis

    Curtis Member

    63
    Feb 6, 2013
    San Antonio, Texas
    320 Sundancer 2004
    Previous 280 Sundancer
    Twin 8.1 (496 Mags) w Bravo III drives
    Thank you, very much!!
     
  14. Craig

    Craig Well-Known Member

    835
    Feb 8, 2007
    Maryland
    2006 320 Sundancer
    twin 350 Horizon V drives
    If you have outdrives it is located on the raw water pump.
     

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