Draining a Yanmar 1GM for winter storage

[BalticPenguin]

I hope it's OK for my first post here to be a question, but it's a bit time-sensitive...

My boat is already on the hard, in a warehouse for the winter. I have a Yanmar 1GM and need to drain the sea water, as it's not unlikely that temperatures drop below 0 °C even in the warehouse. Also note that this is the first time I'm doing this as I only got the boat last year and outsourced this job last winter.

As per the original manual I wanted to drain the sea water by opening the drain cock. Alas, I can't seem to loosen the screw that is supposed to open the cock, and even if I eventually manage to get it to budge, who knows if the water flow won't be blocked by some sludge or whatnot.

I opened up the water pump on the front and let whatever water would drain that way flow out, but I can only assume there's still water in the water jacket and elsewhere which might become a problem if it freezes.

What are my options here? I figure I might try to unscrew the entire drain cock from the engine block, assuming I can reach it with a wrench (it's a bit cramped in the engine bay). Or what about putting the lid back on the water pump, removing the thermostat, and then pouring in some engine antifreeze through the top thermostat hose until the hose runs over? Would that fill the entire cooling system?

Thanks in advance for any advice.

 

[LiftyK]

What I do:

1. fill a bucket with antifreeze
2. disconnect your seawater intake hose from your seacock. Use a heat gun or hot water
3. stick the disconnected hose in the bucket
4. start the engine
5. stop the engine just before all antifreeze has gone
6. Keep the pipe high so the antifreeze stays in
7. Leave the antifreeze in the engine over winter

Some yards do not allow yachts to run engines when on land. In this case, it’s best to flush the engine before craning out.

 

[lexi]

If you are worried about water freezing in block and cannot get drain plugs undone, removing the impeller will drain most out of cylinder head and bock. Lifty;s method is what I have done in past.

 

[BalticPenguin]

Thanks for the replies.

Opening the water pump did let a considerable amount of water flow out, but because the engine sits at a slight angle relative to the floor, I'm pretty sure there's still water in the back of the water jacket. While I think that's probably not going to be a problem, as it should have enough room to expand, I am a bit worried about any water sitting in tight areas where it has less room to expand, like the drain valve.

The yard where I have my boat stored does in fact not allow us to run our engines. However, I was thinking if all else fails I might try opening the decompression lever on the valve cover and running or hand-cranking the engine. That way it at least won't fire, but it should still suck in antifreeze.

 

[Gixer]

If I want to get all the water out of my 1GM10 I remove the anode and thermostat.

 

[BalticPenguin]

If I want to get all the water out of my 1GM10 I remove the anode and thermostat.

But isn't the location of the drain cock lower down than the thermostat and therefore the lowest point in the cooling system?

 

[Gixer]

But isn't the location of the drain cock lower down than the thermostat and therefore the lowest point in the cooling system?

Honestly don't know, 20 years of ownership of a 1GM10 and didn't know it had a drain plug.
Just telling you what I've done to drain the engine.

 

[BalticPenguin]

Honestly don't know, 20 years of ownership of a 1GM10 and didn't know it had a drain plug.
Just telling you what I've done to drain the engine.

How cold does it get where you store your boat?

 

[Gixer]

How cold does it get where you store your boat?

Southeast of the UK so not that cold, maybe -4 max.
Just found an image of where it it, I’ll have a look the weekend!

 

[BalticPenguin]

That's about how cold it gets here too (Western Baltic Sea coast of Germany).

I just checked some photos of the 1GM and the drain cock does indeed seem to be located a bit lower than the anode, the thermostat is relatively high up on the engine block.

So I guess if you never drained your engine through the drain cock, the residual water in there didn't do any damage

 

[hurley]

What I do:

1. fill a bucket with antifreeze
2. disconnect your seawater intake hose from your seacock. Use a heat gun or hot water
3. stick the disconnected hose in the bucket
4. start the engine
5. stop the engine just before all antifreeze has gone
6. Keep the pipe high so the antifreeze stays in
7. Leave the antifreeze in the engine over winter

Some yards do not allow yachts to run engines when on land. In this case, it’s best to flush the engine before craning out.

Don't you need to remove the thermostat otherwise the water will only circulate around the exhaust manifold/mixer and not get into the cylinder jacket... Unless of course you run it for several minutes to enable the temp to increase enough to ensure the thermostat opens. Bw Nick

 

[LiftyK]

Don't you need to remove the thermostat otherwise the water will only circulate around the exhaust manifold/mixer and not get into the cylinder jacket... Unless of course you run it for several minutes to enable the temp to increase enough to ensure the thermostat opens. Bw Nick

Good advice, thank you. Fortunately when I flush my engine it will have been running hard for a good while so the thermostat will have opened. Cheers.