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Engine cooling

Discussion in 'Ask A Hunter Owner' started by Hunter 31, Sep 4, 2017. Add this thread to a FAQ

  1. Hunter 31

    Hunter 31

    Joined Mar 31, 2017
    34 posts, 8 likes
    Hunter 31 31
    us albany, ny Lake George ny
    I have a Fresh water cooling system on my Hunter 31. I believe the engine is a Yanmar 2GM20F.
    Right now I and getting an alarm for overheating. The hose to the raw water pump collapsed and it doesn't seem like I am getting enough water through the through hull going to the sea water strainer. I take the cover off the strainer and open the valve. How much water really should come out?
     


  2. SG

    SG

    Joined Feb 11, 2017
    536 posts, 56 likes
    J/Boat J/160
    US Annapolis
    How much water should come out? Depends on the relative position of the top of the strainer to the sea level.

    The hose to the raw water pump collapsed.
    You mean the supply hose between the strainer (or before it) is flacid or what? I believe, if so, that hose needs to be replaced immediately. It should be too thick, reinforced, etc. for it to collapse or easily bend.

    Do you have a photo of your set-up?


     


  3. Gunni

    Gunni

    Joined Mar 16, 2010
    4,360 posts, 569 likes
    Beneteau 411 Oceanis
    US Annapolis
    Stop running the engine until you can fully inspect the raw system. That includes the intake hose, and thru-hull. You most definitely are NOT getting enough raw water. The hose is collapsing because it is either deteriorated or you have a plug in the raw water intake.
     


  4. Benny17441

    Benny17441

    Joined May 24, 2004
    5,185 posts, 254 likes
    CC 30
    US South Florida
    Remove the hose at the thru-hull and open the valve; the stream should be round and strong for 2-4 inches. If it is just a dribble or not very strong you have a likely blockage in the clam shell. I would first try compressed air to blow out what is plugging it. A few years ago I had a similar situation where we picked up a plastic ice bag. The thing is it was acting like a flap valve, we could blow air out but when water tried to get in the flap would close and obstruct flow. At the time we did not know what it was but diving under the boat revealed the culprit which was removed. Whether to first dive or try compressed air is your choice. Don't forget to inspect the raw water pump impeller.
     


  5. Ralph Johnstone

    Ralph Johnstone

    Joined Jan 4, 2006
    2,385 posts, 223 likes
    Hunter H-310
    CA West Vancouver, B.C.
    The required hose on the pump suction is wire impregnated and you most likely have a blockage upstream of the pump.
     


  6. Meriachee

    Meriachee

    Joined Aug 1, 2011
    1,944 posts, 356 likes
    Catalina 270
    CA Edmonton, Ab Wabamun - on the orange ball
    Not to mention that the heat exchanger won't, and something expensive will melt as a likely result.
     


  7. Hunter Ad Bot

    Hunter Ad Bot

    Joined Oct 27, 2016
    0 posts, 6 likes
    US Seattle
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  8. jssailem

    jssailem

    Joined Oct 22, 2014
    3,380 posts, 671 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    H3 You'se got trouble... I mean trouble... Trouble right here in River City...
    Lots of water should be coming out. Hoses should not collapse.

    Besides the strainer and the thru hull valve, do you have a grate on the outside of the thru hull? Something is blocking the inflow of water, causing the hose to collapse. (you will need a new hose... wire reinforced) Clear the blockage, check the raw water impeller, check the hoses and connections to the heat exchanger, check the heat exchanger... Why all of this extra? Because if the something blocked your intake then in all possibility some of the contaminant may have worked it's way further into the system. Breaking impeller arms or plugging the small tubes of the heat exchanger. Cool water is the savior of your engine.
     


  9. djekels

    djekels

    Joined Jul 21, 2014
    22 posts, 0 likes
    Hunter 30T
    US Monroe
    what do you use to report overheating engine temp?
     


  10. Hunter 31

    Hunter 31

    Joined Mar 31, 2017
    34 posts, 8 likes
    Hunter 31 31
    us albany, ny Lake George ny
    The alarm and light came on.
     


    djekels likes this.
  11. Hunter 31

    Hunter 31

    Joined Mar 31, 2017
    34 posts, 8 likes
    Hunter 31 31
    us albany, ny Lake George ny
    I am going to take the raw water pump off to look at it, replace the suction hose, make sure the strainer is not clogged and look at the rest of the system for clogged heat exchanger.
     


  12. jviss

    jviss

    Joined Feb 5, 2004
    2,000 posts, 122 likes
    Tartan 3800
    US Westborough Westport, MA
    Take the end caps off the heat exchanger. If you can look through the tubes, great. If not, try fishing something soft through the tubes, like heavy, monofilament fishing line. There might be crud from the zinc clogging things up.

    The collapsed hose could be just the hose! It certainly should be wire-reinforced.
     


  13. Warren Milberg

    Warren Milberg

    Joined Dec 1, 1999
    2,308 posts, 67 likes
    Hunter 28.5
    US Chesapeake Bay
    If the raw water hose really is "collapsed," my guess is that there is a blockage between the raw water pump and the raw water intake. As the impeller turns it would create suction on the intake hose and if no water is passing the hose might "collapse." A plastic bag or other solid trash stuck in the raw water thru-hull might be the cause.
     


    Gunni likes this.
  14. Hunter 31

    Hunter 31

    Joined Mar 31, 2017
    34 posts, 8 likes
    Hunter 31 31
    us albany, ny Lake George ny
    Thanks all: Im going to the boat wed night ill let you know what I find.
     


  15. Hunter 31

    Hunter 31

    Joined Mar 31, 2017
    34 posts, 8 likes
    Hunter 31 31
    us albany, ny Lake George ny
    Thanks everyone.. I went to the boat, pulled the raw water pump and found the impeller was missing two veins, they were gammed in the discharge of the pump. Found the end of the raw water hose collapsed, looked like it was taken off too many times. pulled the hose off the sea chest and checked for flow, all was good, pulled the thermisat and heated it with a torch, works. pulled the end cap of the heat exchanger off, all was clean. back in business.. thanks
     


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  16. jssailem

    jssailem

    Joined Oct 22, 2014
    3,380 posts, 671 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    DJ. I have a temp gauge on the engine panel. I also have a horn that sounds if temp reaches 200 degrees. Routine to check engine temp about every 45 minutes of engine use.
    If temp shows above 170 I use a thermal temp gauge and test several identified places to compare against previous records.

    Only time my temp alarm sounded was when the water pump shutdown. Blew the bearings. Emptied the engine coolant. Able to shut engine down and escape damage.
     


  17. All U Get

    All U Get

    Joined Oct 2, 2008
    2,346 posts, 179 likes
    Pearson/ 530
    US Strafford, NH


  18. Ken Cross

    Ken Cross

    Joined Oct 24, 2010
    1,404 posts, 139 likes
    Hunter 30
    US Everett, WA
    I found a .22 caliber gun cleaning rod with a brush on it fits the heat exchanger perfectly. At least it did on our 2GM20F
    Ken
     


  19. jssailem

    jssailem

    Joined Oct 22, 2014
    3,380 posts, 671 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    You have a good idea. The exchangers I have seen can be cleaned with a .22 cal rod or one of the new cable brushes pulled through the tubes with a wire cable.
     



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