Winterising a Yanmar 2 GM

[DanTribe]

I've been preparing my 2GM [raw water cooled] for winter and thought it would be a good idea to flush through with antifreeze.
I removed inlet pipe from seacock & imersed in a bucket of diluted antifreeze. Started up but no suction, so lifted the pipe to prime pump, no good. By this time the temp warning goes off.
I removed pump to check impellor but it looks OK so refit and reconnect pipe to seacock. Pump now OK. [Engine has cooled by now]
"Thinks" Perhaps not enough head of water for pump to work. So raise inlet pipe to approx waterline and fit large funnel filled with antifreeze, [carefully avoiding kinks to prevent airlock]. No flow!
Return config to original and all works fine.
Is there some reason that these pumps will pump seawater but not antifreeze, or have I missed something bleeding obvious?

 

[wotayottie]

you must have missed something bleeding obvious since the pump isnt clever enough to tell the taste of antifreeze from salt water. For example, have you got a kink in the pipe when you stuck it in the bucket, and where was the bucket in relation to the engine.

Cant solve your problem from here . You need to go back to the boat and try again, but before you start the engine, look at your set up very carefully to spot what is wrong.

I always used to use a mixture of antifreeze and cutting oil on the theroy that the latter would prevent corrosion.

 

[martinriches]

Don't know what seacock you have. On mine you can take the top off and pour the antifreeze in with a jug, having closed it first of course.

 

[vyv_cox]

One suggestion. If the cover plate on the pump is worn it can be very reluctant to suck water, even if you raise the suction hose above it. In many installations the seawater level is higher than the pump, so in the time it takes to reconnect the hose back on the seacock there is sufficient head to drive a little water through. I suggest you check your cover for wear, but in any case grease the impeller before trying again, to improve the pump suction.

 

[MrCramp]

I had a 2GM20 in my last boat and got a problem with the water flow at low revs. I took the pump apart and it had a slightly worn cover plate. I had it skimmed and the problem went. So I agree with vyv-cox, that is likely to be where your problem is.