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  1. #1

    Default 2007 496 Ho mag coolant Tank keeps overflowing

    my engine has not yet over heated or any alarms but all of a sudden my coolant tank is empty and when i fill it up it starts to fill up and overflow

  2. #2
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,768

    Default Re: 2007 496 Ho mag coolant Tank keeps overflowing

    Ayuh,..... Sounds like ya got a leak,...... drain it, pressure test it,..... follow the sound of the escapin' air,......
    Any Grease is Better,... Than No grease at All....

  3. #3

    Default Re: 2007 496 Ho mag coolant Tank keeps overflowing

    What do you mean leak and listen to air ?

    could The overflow be caused by a bad heat exchanger ? A bad thermostats? Or and issue with my hot water heater?

  4. #4
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    5,376

    Default Re: 2007 496 Ho mag coolant Tank keeps overflowing

    Things that will over fill your expansion tank:

    Blown head gasket
    Leaking Heat exchanger between the sea water and coolant with a blockage in the raw water side sending the pressure in the exchanger over the limitations of the pressure cap.

    The water heater can do this if the coil inside is compromised and the domestic water system is pressurizing the antifreeze side, but not likely.


    I would say your exchanger is leaking and your raw water side has high pressure.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  5. #5

    Default Re: 2007 496 Ho mag coolant Tank keeps overflowing

    Hello again everyone.

    Chris thank you for your detailed response. Today I bought a new heat exchanger. Which was expensive. I took the old one out along with the crossover. I noticed salt residue in the crossover. I clean it out replace all gaskets and swap out the heat exchanger. I ran the engine on low and high idle. And the water in the reservoir stayed pretty Mich the same. Unlike before it would fill the tank up in 30min. I have not sea trailed it yet. But I hope froml what I sea on high idle and low idle, I believe we are good and the problem has been fixed. I’m still spectacle on the hot waterl heater. It’s old and still all original.

    Any my more thoughts on my case would be appreciated.

    Thank you !!

    luis V

  6. #6
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    5,376

    Default Re: 2007 496 Ho mag coolant Tank keeps overflowing

    Most exchangers just lose coolant into the sea water, If you were pushing sea water into the Coolant side of the exchanger, you need to check the pressure in the raw water side!

    If you have a smartcraft gauge you can see what the pressure is. If not, find someone who has a scan tool.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

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