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Flushing cooling system

Discussion in 'Ask All Sailors' started by NYSail, Oct 12, 2017 at 6:29 AM. Add this thread to a FAQ

  1. NYSail

    NYSail

    Joined Jan 6, 2006
    1,486 posts, 30 likes
    Beneteau 423
    US Mt. Sinai, NY
    So I am getting ready to change antifreeze and all hoses...... Will flush the system a couple of times with fresh water to get all old stuff out prior to putting new 50/50 mixture in. However does anybody additionally use any commercial flush products and if so what do you use that is gentle on the marine engine parts. My engine is running fine, just don't know when it was done last if at all. Engine has about 575 hours.

    Thanks
     


  2. Bill Roosa

    Bill Roosa

    Joined Jun 6, 2006
    6,859 posts, 99 likes
    Hunter 40.5
    US Harrington Harbor North, MD
    only need to use flushing chemicals if there is excessive rust. If the fluid comes out red, orange or green but not a dirty rust brown then you don't need chemicals.
     


  3. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    Just curious, how old is the boat, and what prompted the desire to change the coolant and hoses?
     


  4. NYSail

    NYSail

    Joined Jan 6, 2006
    1,486 posts, 30 likes
    Beneteau 423
    US Mt. Sinai, NY
    New to me. 2005. Looks all original. Hate to be Stupid over a few bucks.
     


  5. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    Ah, O.K. Makes sense. I found what I think is an original hose on my new-to-me 1996 boat.

    There are quite a few hoses on mine, and they are not exactly cheap to buy, for example, the wire-reinforced, marine hose; and, it would be time consuming to replace them all, especially the ones running to the rather remotely located water heater. So, yes, DIY is just your time, but at $100/hour, it will add up.

    I will replace those that are obviously old, visibly deteriorating, i.e., surface cracks, and those that don't feel firm and fresh, i.e., those that are "squishy," soft. I will log what I do! I wish I had complete, thorough maintenance logs for this, as one would for an airplane. I also have on funky seawater hose with a nylon elbow in the run that I will sort out.

    What do you think, 5 years for a hose?
     


  6. leo310

    leo310

    Joined Dec 15, 2006
    10 posts, 1 likes
    Catalina Catlina 310
    CA Campbell River BC
    I have a question have you replaced your car/truck hoses? I know I haven't and its been ten years on the car but the boat fluids have been changed every 3 years, oil once a year or 75 hours.
     


  7. NYSail

    NYSail

    Joined Jan 6, 2006
    1,486 posts, 30 likes
    Beneteau 423
    US Mt. Sinai, NY
    My thought is that I would hate to be 50 miles off shore, or motoring into a harbor in a storm and an old hose breaks..... things go downhill real fast! The boat is 12 years old and I would like to start fresh.....

    In my car, well if a hose goes I pull over and call the auto club.
     


  8. Johnb

    Johnb

    Joined Jan 22, 2008
    996 posts, 62 likes
    Hunter 37-cutter
    US Richmond CA
    Even if you can pull over and call the auto club are you sure you won't have warped a cylinder head in the overheating incident? I figure you are wise to proactively replace those "rubber" pieces. On my Yanmar 3QM30 quite a lot of work had to be done to get at some of the hoses. By the time you have gathered the new parts, scheduled the work, drained the system and got your hands dirty you might as well do all of them. And get all new hose clamps as well.

    When I got my boat I double flushed the cooling system. I don't know if you really need to, but I use distilled water to mix with the anti freeze - and replace every 3 years (it is the 5 year stuff). Also got a new "radiator" cap and cleaned out the expansion tank. Net result - 15 years totally trouble free on the "fresh water" side of the cooling system.

    That engine is worth looking after.
     


  9. Bob S

    Bob S

    Joined Sep 27, 2007
    1,298 posts, 9 likes
    Beneteau 393
    US New Bedford
    It's easy to inspect the hoses that are visible but the ones that go to the water heater are the ones that I would be most concerned with because you can't see them. While running wires on my Catalina 30 I had removed the cabinet draws to gain access and found the water heater hoses to be badly cracked at a bend and would never had noticed them if I hadn't been in there.

    I'm not sure I would replace all my hoses just because I'm in there but I certainly would inspect them!
     


    jviss likes this.
  10. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    Good point, Bob. I re-did just about all the hoses on my 1984 C36 this year. Many were original, I suspect, and many were broken, including the cockpit scupper hoses, and exhaust hose (in two places). I also replaced the sewage hoses.
     


  11. NYSail

    NYSail

    Joined Jan 6, 2006
    1,486 posts, 30 likes
    Beneteau 423
    US Mt. Sinai, NY
    I believe in new hoses.... bought all yanmar specific hoses for engine, new hoses for water heater, new thermostat (why not....) and a new cap. Have plenty of nice Shell ROTELLA ELC all ready to go! Actually while doing this I am going to remove
    My hot water heater so I can clean 12 years of crud from underneath in the bilge.
     


  12. Gunni

    Gunni

    Joined Mar 16, 2010
    4,350 posts, 565 likes
    Beneteau 411 Oceanis
    US Annapolis
    You don’t need to flush the coolant circuit unless you areh experiencing overheating. Since this job should be done every year or so any problem can be monitored. What I would be more concerned by would be a potential breach of your HW heat exchanger which would put toxic EG antifreeze in contact with your potable hot water. Fleetguard and StarBright both make excellent engine PG antifreeze and they are compatible with residual EG antifreeze. I would keep the hoses as spares and work on a good fresh water flush (or three).
     



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