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Flushing a Honda 9.9

Discussion in 'Ask A Macgregor Owner' started by danphilgreen, Nov 14, 2017 at 2:05 PM. Add this thread to a FAQ

  1. danphilgreen

    danphilgreen

    Joined May 23, 2011
    31 posts, 5 likes
    MacGregor 26S
    US Fort Myers
    Hello friends. I'm told that regular flushing of an outboard used in salt water has a huge impact on the life one can expect to get out of said motor. I recently purchased a very low time used Honda 9.9 outboard. Miraculously, it came with the manual. Said manual stated that the engine could be run in the 1st and 2nd tilt up positions, but not in the 3rd, which is the only one that sees the engine clear of the water in my installation on a Mac 26S. I wondered about how to properly flush the motor since it seems I could not run it tilted out of the water. I called a local Honda Marine dealer, Gulfside Marine Services in Matlacha, FL, who spent quite a long time generously giving me information about this topic and my motor in general. There are a couple of approaches. There is a port in the power head under the cover where you can attach a garden hose with a fitting that comes with the motor. (Which also was miraculously provided with my used motor - previous owner was a bit OCD about keeping track of parts, paperwork, and maintenance, God bless him!) It's a bit of a thing to get this port configured - you need a wrench - and there is risk of loosing either the port plug or said hose fitting in the drink. It does flush and it does get behind the cold/closed thermostat to an extent (there is a small bypass that is always open), but it does not flush as thoroughly as using muffs on the lower unit intakes. It's important to know that this port supplies water after the water pump, so you must not run the motor in this mode or the dry impeller will likely be ruined. So, the better flush is with a regular old muff attachment on the lower unit. The engine runs, gets warm, the thermostat opens and the flush is much better. The tech told me that it's best to flush with the motor running vertically. So, he said to tilt the motor, install the muffs, get the hose running, then tilt the motor back into the water and run it with the muffs down under water and it will work fine. Then after the run, shut it off, tilt it up, and after it's out of the water, shut off the hose and remove the muffs. Then rinse off the lower unit. I've heard elsewhere that you can get corrosion from salt water trapped in the prop hub when you tilt it up. So just to be safe, I plan to rinse out the hub real good to make sure there is no salt water in there. Btw, I noticed that the Honda streams out the pee hole even when it's cold. The old '90 Merc 2-stroke only streamed after the thermostat opened, which could be disconcerting. I also learned that the rubber tube feeding the hole on the Honda is prone to clogging. Anyway, make sure you floss your teeth and flush your motor! If you sail in fresh water, count yourself lucky in this regard!
     


  2. danphilgreen

    danphilgreen

    Joined May 23, 2011
    31 posts, 5 likes
    MacGregor 26S
    US Fort Myers
    Related note: I asked the Honda tech about using Salt Away with an injector on the hose. He didn't seem to have much of an opinion one way or the other about Salt Away. From what I've read it seems to be a very good product but the plastic injector they sell is expensive and breaks easily. Another more robust detergent injector was suggested but seems to no longer be available. Still looking for a solution as I think I'd like to use this product for flushing.
     


  3. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    215 posts, 40 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    Do you keep your boat on a trailer? I run my tender motor in a 5-gal. pail of fresh water at end of every trip.
     


  4. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,549 posts, 351 likes
    Lancer 27PS
    US Oceanside, Ca MCB Camp Pendleton, Ca KF6BL
    My Yamy 9.9 has the flush hose. The motor I had previous did not. I used the muff method. But I also found that I could back flush through the pee hole tubing. Had to keep the water pressure down but it worked like a charm. Just a few parts from HD, connect to the pee hose and watched the water exit out the prop hub. Not sure if it did what real flushing did, but it worked.
     


    danphilgreen likes this.
  5. danphilgreen

    danphilgreen

    Joined May 23, 2011
    31 posts, 5 likes
    MacGregor 26S
    US Fort Myers
    I keep it on the trailer at my house some of the time but for the last couple of years I’ve had the luxury of being able to keep it at a dock at a friends house for months at a time. So finding a way to flush the motor with the boat in the water was my goal.
     


  6. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    215 posts, 40 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    Still do-able with a bucket but a PITA. I believe you don't want to run a 4-stroke tilted because of oil level.
     


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  7. jeepbluetj

    jeepbluetj

    Joined Jan 18, 2016
    349 posts, 84 likes
    Catalina 30
    US SoCal Dana Point
    I would do exactly what the mechanic suggested - put the muffs on, turn the water on, stick the motor in the water and run it.
    Pull it out with the muffs on and spray out the prop hub. It'll be fine.
     


    danphilgreen likes this.
  8. Ron20324

    Ron20324

    Joined Jan 22, 2008
    5,625 posts, 368 likes
    Beneteau 323
    US Annapolis MD
    That rubber pee tube is on a lot of motors, and can be clogged by insects (mud daubers), so it's not a Honda thing. Also, if the water pump is taking in water, it has to come out somewhere, lest the systems become pressurized and pop a gasket before the theromo opens up.
     


    Last edited: Nov 14, 2017 at 7:42 PM
    danphilgreen likes this.

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