Trying to change coolant on Yanmar 3GM

[dart]

I’m trying to change the fresh water coolant on my Yanmar 3GM. There seem to be 3 drain plugs with pipes going down to the bilge (2 on one side 1 on the other). When I open the cocks nothing comes out (the coolant is full!)

Any ideas what I could be doing wrong?

Thanks Chris.

 

[PaulR]

have same engine on ours and have yet to drain coolant - have you opened the header tank as i wonder if there is a sealed vacuum affect and if you don't allow air in water can't get out?

might be worth trying

 

[steve28]

most of the time the drain cocks or clogged up i always had to unscrew the plastic bung(dont loose it like another forumite!) then using a slim flatbladed screwdriver press and turn in the hole and you will find normally grit and rust will come out. once its running its fine and you can replace the bung to allow it to run down the tube.
I have always used antifreeze in mine and have never had any probems since.

It could be what the other poster has mentioned as well.


steve

 

[Col]

Agreed

 

[dart]

Thanks very much all, that all sounds good. Will give it a go and report back /forums/images/graemlins/smile.gif

 

[dart]

Well in the end I had to blow down the expansion tube and blow it out!

Cheers Chris.

 

[Aeolus_IV]

I can see that I am late to this one ... I did this on my 3GM30F at the last service, I needed open the cap on the heat exchanger to allow air into the system. It poured out at that point - the plastic tray I had under the engine to catch it all was nearly too small.

But all's well, that ends well.

I found that it took some time for the engine to circulate all of the air out the system (especially as I had just plumbed in a calorifier), so it is worth checking the level before you start the engine (while its cold), just in case it needs a top up.

Regards, Jeff.