Diesel engine fresh water flushing - Does anyone bother?

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StevenJMorgan

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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!
 
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.
 
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.
 
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
 
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
 
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.
 
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.
 
jerryat said:
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.
Click to expand...

Sorry to drag back an old thread but this sounds like a good idea and I've never heard of it before. Is this relatively common practice to use some sort of oil to coat your raw circuit while winterising / laying up?
 
northcave said:
Sorry to drag back an old thread but this sounds like a good idea and I've never heard of it before. Is this relatively common practice to use some sort of oil to coat your raw circuit while winterising / laying up?
Click to expand...

It used to be fashionable, in olden days when this thread was alive. FFS it's over 12 years old!
 
pvb said:
Because engine manufacturers generally no longer recommend it. How did you even find a 12 year old thread??
Click to expand...

I just search google for "YBW flush engine".... google is a way better search than the forum search. I find most of my boat answers that way rather that just posting something that's already need answered. Although you would believe it recently given how many new threads I've started.
 
I stopped doing it (mixed with antifreeze) when I couldn't buy the oil any more from the chandler who said that antifreeze was just as good on its own.

32 year old raw water cooled Bukh 20. I guess I gave up using the oil over 25 years ago...at least.
 
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I think the salt removal tablets are well worth using every so often. It is easy to drop a few in the strainer and run through the engine.
 
northcave said:
Sorry to drag back an old thread but this sounds like a good idea and I've never heard of it before. Is this relatively common practice to use some sort of oil to coat your raw circuit while winterising / laying up?
Click to expand...

BUKH DV20 manual said to flush with Shell ENSIS oil when storing for extended periods. Earlier post mentioned emulsifying oil for his BUKH as per instructions in the manual. No idea main reason why it isn't common now.

Too much trouble for most owners so why bother mentioning it in owner manual?
Engine not built to last 30+ years in first place?
Fewer raw water cooled engines?

Perhaps it is a combination of several factors, someone might have more of a clue.
 
Someone once recommended a litre or two of white vinegar poured into the sea water strainer at shutdown and left there for a week - every six months or so. I see a satisfying burst of white sediment out of the exhaust when starting up after the requisite week. No harm yet after 13 years service.
 
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