Draining Yanmar 2GM20

[richardabeattie]

There's a plastic knob on the starboard side which looks like a water drain but when I open it nothing comes even if I poke about inside it. But as soon as I take the engine anodes out, or disconnect the pipe at the impellor, out comes the water. So what's the plastic knob for please?

And what is the forum view - leave the engine full of fresh water and antifreeze or run an emulsion of inhibitor oil & water through it and then drain it down again?

 

[ronniewood]

Don't know about the knob on the side but we run an inhibitor oil, antifreeze and freshwater mix through and leave it. Done it for ten years and no problems even at -15C.
Know of several others that do the same also with no problems.

 

[snowleopard]

Yes, it is the engine drain - you must have some sludge blocking it. I suggest you connect a hose or air line to blow the gunge back into the block, then flush it through.

 

[eebygum]

Definately the seawater engine drain. I was going to drain my 2GM20 at yesterday but ran our of time. As I could'nt start up the engine as it's in a cradle and the marina are not keen on this I adopted plan B which my marine engineer recommended .....Disconnect the sea water water intake at the sea-cock end (easist place to do this on my boat) and then disconnect the seawater outlet rubber hose to the exhaust and pour the anti-freeze mix in from the top. Let it drain down until it then starts to come out the bottom hose.

Not as good as flushing but at least you have more confidence that you have some antifreeze in.

Cheers

 

[Cloven]

Richard

There are TWO of these plastic drain knobs. The upper one will drain very little but the lower one which is more difficult to find/access is the main drain plug. Can I suggest that you have another look and make sure you are opening the main drain plug before some of the more drastic measures suggested above.

Hope this helps

 

[steve28]

The upper one mentioned is only on the fresh water cooled version, the lower one will need reopenng either with a metal coathanger or a long thin screwdriver.
I always periodicaly open it whilst the engine is running and drain it to keep it clear.

steve

 

[richardabeattie]

Thanks everybody - mine is raw water cooled so I think has only the one drain and yes I did try rodding it with the plastic knob completely removed but to no effect.

I am nervous about pumping water through as last winter I did just that and subsequently had to replace the piston rings - I must have overdone it and filled up the water trap in th eexhaust!
However plenty of water came out through the lower of the two anode holes and from the pipe leading from impeller to the block so I hope I have got most of it out. The other Question is whether it's better to leave the block empty after flushing it with inhibitor or to leave it full with water and antifreeze. I also use a greenhouse heater which might help a bit

 

[Aja]

It also helps to undo the water fill cap onto of the engine. If you dont do this water is usually very reluctant to drain due I think to syphoning.

Donald

 

[richardabeattie]

Water filler? Mine is raw water cooled and has no filler that i know of.

 

[Aja]

Sorry. I was thinking of the 2GM20F

Donald