Boat Engines

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    [size=84:1u51hmsm]Flush your engine with fresh water as soon as possible after each use in salty, polluted, or brackish water to minimize the formation of deposits that can clog cool


    I’ve recently bought a boat with a “saltwater series” yamaha 115 2 stroke that apparently can be flushed without running the motor.

    I’m not sure if this flushing technique is better/same/worse than using the muffs while running the motor, does anybody know?



    I know the thing you are talking about. My understanding is that you don’t need to run the motor. Just get the correct hose fitting to connect the hose to the socket and let it run for five minutes with the motor off.
    Yellowfin :)


    Hi Guys,

    Flushing your outboard is the most important maintenance proceedure you can perform to prolong the life of your outboard.
    I know some outboard manufaturers say you can flush your outboard cold without running your engine, but this does not successfully remove all salt deposits from the internal waterways of the engine, this can only be achieved by running the engine and bringing it up to normal working temparatures.
    The removal of salt from your engine is vital so as not to get build up in hard to flush places which in turn produces engine wearing hot spots.
    Flush muffs do the job quite well, but there is always concern as to whether the pump and engine are getting enough water.
    Flush tanks are a far better option and I have had three in the past, all of which worked well, but they wore out after a year or so by getting holes in the bottom.
    These failures made me think of building a flush tank that still collapsed down for easy storage, but was far more resiliant to wear and my company now produces the “Kiwi Flush”an exclusively Kiwi made product which is far superior to any other PVC flush tank ever made before.
    Our “Kiwi Flush” has a 4mm PE plastic protective domed base.
    We will be launching the product in early October and will take all orders via email or phone.
    We will ship anywhere in NZ at the normal freight rates.
    The Kiwi Flush will be on our website very soon


    I’m new to boating and am wondering if the engine I’ve bought has a problem or if my experience is normal.

    I had my boat at home on its trailer with the OB down in its ‘running’ position’ – its a 4M fibreglass runabout with 25HP Mercury OB. I ran it with muffs connected to a hose for about 4 minutes – between idle and probably 2/3rds full revs. The ‘tell tail’ water flow was good and the engine sounded good.

    I then cut the engine, disconnected the muffs/hose, lifted the OB, and lifted the front of the trailer up and hosed down the inside of the boat – after taking the drain plug out!

    After I finished, I left the boat to dry for about 1/2 an hour, then put the trailer back down on a level and pushed the boat into the garage. Once in, I put the OB back down into its ‘running position’ so that I can push it further in and close the door.

    When I lowered the OB, I noticed that a small puddle of oil accumulated under it. On the flat concrete it spread out to about 10cm diameter. It was difficult to tell, but I think it was coming from where prop meets gearbox housing.

    Is this normal? Is it just unburnt 2-stroke oil that pooled somewhere in the exhaust system when the OB was raised and then drained when the OB was lowered? I can’t think how it could be gearbox oil because it was not put in gear.

    smokin’ joe

    how long had the motor sat, before you fired it up??
    was the fuel fresh??

    i had a similar scenario with a couple of motors i have here, including the one on my tinny.

    if the motor hasn’t been started for a long time, the petrol evaporates from the oil and the excess oil will exit out exhaust.

    i’m not a fan of the flush muffs, especially when a cheap plastic drum/bin can get full immersion, and don’t require running water. using a drum or bin, won’t annoy the neighbours as much, as the exhaust is underwater.


    G’day smokin’

    Good thought. The 10L tank was 1/2 full when I got it and I added 5L of petrol and 100ML of oil – don’t know how long the original 5L had been sitting in it. So its possible the original 5L may have got a bit richer than the 50:1 mix.

    I had been running the boat out in Lyttleton for an hour the night before – but was too late to flush when we got back – as you say, consideration to neighbours! So the flushing was done at about 10AM the next morning.

    I’ll have a hunt around the garage for a drum of some kind and maybe head off down the plastic box shop if I can’t find 1.

    smokin’ joe

    unsure what CHCH has for recycling bins, but the 60L-ish rectangular bins in Kaikoura are ideal 8) .
    Alternatively, industrial chemicals often come in either 100 or 200L plastic drums and are easy to cut down with a hand saw or jigsaw. they can be found almost anywhere like freezing works/tanneries etc , anywhere that highly acidic/alkaline fluids are used.
    keep your eyes peeled next time you are at Lyttleton (a small fee may be required).

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