Winterising Engine

[comino]

Is it a good thing to close the engine seacock and start it for a few seconds to blow out the water, leaving the engine dryish inside. It's a Yanma 3YMO and the boat will now sit in the water in a marina till next April when we return to the Med. Many thanks.

 

[Mistroma]

Is it a good thing to close the engine seacock and start it for a few seconds to blow out the water, leaving the engine dryish inside. It's a Yanma 3YMO and the boat will now sit in the water in a marina till next April when we return to the Med. Many thanks.

I don't think that would achieve much as you'd be sucking against a closed valve. You'd probably just push a little water out of the exhaust trap.

You can fresh water flush by closing the valve, opening the strainer lid (assuming it is above sea level) and feeding fresh water from a hose. Then you can put in a small rinse with neat antifreeze to reduce corrosion.

If a shore hose isn't available then I use the shower hose on my boat as the strainer is next to it. It just about matches the water needed and you don't need that much. You can always do a couple of runs before adding antifreeze and let the freshwater sit for a while.

 

[nortada]

I don't think that would achieve much as you'd be sucking against a closed valve. You'd probably just push a little water out of the exhaust trap.

You can fresh water flush by closing the valve, opening the strainer lid (assuming it is above sea level) and feeding fresh water from a hose. Then you can put in a small rinse with neat antifreeze to reduce corrosion.

This is exactly what we do and it seems to work. In addition, to minimise the problem of contamination of the fuel, we doctor the fuel tank with biocide, both when winterising and start up next Spring.

 

[Mistroma]

This is exactly what we do and it seems to work. In addition, to minimise the problem of contamination of the fuel, we doctor the fuel tank with biocide, both when winterising and start up next Spring.

Yes, I've just added a double dose of Marine16 to the tank a couple of days ago. Small amount left in one can also dosed and then swirled around all the other cans. This removed a tiny amount of contamination and means they should be fine for next year. Probably worth mentioning to OP in case he hasn't done this yet.

I actually think it would be better to leave the fuel tank empty over winter with inspection cover open. But it's easier to top up at end of season because the tank is usually pretty full anyway. I'll be doing the oil and filter change in a couple of days but usually leave the fuel filter until start of next year.

 

[vyv_cox]

As said, running the engine with the inlet seacock closed will achieve nothing and might even cause damage. I carry two 11 litre bottles for fresh water and after haul out I run a full one of these through the engine via the Vetus water strainer. Close the seacock first to avoid overspill running away. You could do the same with a bit of antifreeze for its corrosion inhibition content but probably the benefits are illusory. On Yanmar engines the heat exchanger is the only metal component and is at the highest point, so it drains immediately.

 

[AndrewB]

As said, running the engine with the inlet seacock closed will achieve nothing and might even cause damage.

Yes, to the impellor.

My standard wintering practice, adopted from many similar threads on these forums, is to take off the raw water hose at the seacock (close the seacock first!) and stick the end in a bucket with a few litres of antifreeze (50% mix), then turn over the engine with the starter motor to suck it through. And to answer the next question, antifreeze will not damage the impeller which can be left on, though should be inspected (some would say replaced) as part of a winterising routine.

Done mainly to protect the manifold from corrosion. It is rarely cold enough in the UK that salt water in the engine raw water system will freeze.