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  1. #1
    Join Date
    Mar 2004
    Posts
    82

    Default Diesel engine fresh water flushing - Does anyone bother?

    Many of my friends fush their outboard petrol engines with fresh water after every use in saltwater.

    My engine - volvo 2030 with raw water, heat exchanger and fresh water 'internal' cooling. Would I help extend the life of my engine if I fitted a Y valve to the raw water intake before the pump so that I could hook up a fresh water hose and flush out the salt every now and then? I understand that the outboards need it more as they are entirely salt water cooled but I thought that by flushing I could help my engine last longer.

    Has anyone tries this? Is it worth it? or am I being over protective of my pride and joy?? PS my boat is in arabian gulf so very salty!

  2. #2

    Default Re: Diesel engine fresh water flushing - Does anyone bother?

    If you are about to leave your boat for a month or more it could arguably be worth it, but not for shorter periods. I flush mine out well when laying up and follow up with anti-freeze for the benefit of the inhibitor it contains, but I never bother at any other time.

  3. #3
    Join Date
    Jun 2004
    Posts
    517

    Default Re: Diesel engine fresh water flushing - Does anyone bother?

    As Medman, I have just hauled out for the winter as I need some work doing on her. Have a Volvo 2003T, I disconected the water inlet and connected a hose pipe and ran the engine for a few minutes, then made a 50/50 antifreeze / water mix in a bucket and put the inlet into that and let it suck it through for its anticorrosive properties.

    I dont think the previous owner bothered and I had a pinhole appear in the copper raw water pipes a while ago, I am assuming this means that they all now need replacing.
    I also removed the pump impeller, changed the oil and filter and cleaned the air filter.
    Of course this is for a long lay up, I wouldnt bother for short periods.

    Re the y valve - nice idea and convenient, but its so easy to do any way Im not sure as to the need.

  4. #4
    jerryat is offline Registered User
    Location : Nr Plymouth
    Join Date
    Mar 2004
    Posts
    3,571

    Default Re: Diesel engine fresh water flushing - Does anyone bother?

    Hi,

    I think it's well worth doing at lay-up, though probably not not during the season.

    FWIW, I flush my raw water cooled Bukh through (recirculating via a bucket under the exhaust) using fresh water mixed with an emulsifying oil. This coats the inside of the waterways with a film of oil and prevents rust forming.

    When I stripped the engine down for a major refit last winter, there wasn't a sign of corrosion anywhere, which can't be bad for a twenty year old (though well maintained) engine!!

    Cheers Jerry

  5. #5
    PCUK is offline Registered User
    Location : Mid Devon
    Join Date
    Jun 2005
    Posts
    4,735

    Default Re: Diesel engine fresh water flushing - Does anyone bother?

    As you have a heat exchanger, salt water doesn't enter the engine. Flush the raw water system during lay-up and rod through all the water stack tubes to keep them clear.
    Under every pony's tail is an ****hole.

  6. #6
    jerryat is offline Registered User
    Location : Nr Plymouth
    Join Date
    Mar 2004
    Posts
    3,571

    Default Re: Diesel engine fresh water flushing - Does anyone bother?

    Hi Pershilla,

    Did you read my post? I have a RAW water cooled engine, so the emulsifying oil goes throough EVERY part of the cooling system!!

    Cheers Jerry

  7. #7
    Join Date
    May 2001
    Posts
    1,089

    Default Re: Diesel engine fresh water flushing - Does anyone bother?

    As the only bits the sea water passes through are the Raw water pump, heat exchanger and possibly the oil cooler, only worth doing before laying up.

  8. #8
    Join Date
    Jan 2004
    Posts
    797

    Default Re: Diesel engine fresh water flushing - Does anyone bother?

    Please see my earlier posts about my Yanmar problem. To flush out the engine I connected a jerrican of water by a hose clamped to the impeller intake and stood the jerrican on the bunk base. The water level in the jerrican was then higher than the impeller and probably higher than the siphon break in the exhaust. The piston rings jammed up and I was lucky not to bend the con rods. Any flushing water has to be sucked in by the impeller not gravity fed.

  9. #9
    bob_tyler Guest

    Default Re: Diesel engine fresh water flushing - Does anyone bother?

    NEVER connect a fresh water hose to the raw water inlet. The pressure can damage the impeller. Let the impeller suck the water in from a can or bucket placed at the lowest point possible thus imitating its normal method of operation. The can or bucket can be topped up with fresh water from the gently running hose.

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