Yanmar 2GMF - freshwater drain

[davel]

Yanmar 2GM20F - freshwater drain

Hope someone with practical knowledge of this engine can help.

I went to drain the fresh water from the engine today. According to the service manual, there should be a drain plug fitted to the engine block just below and to the right of the water inlet pipe to the cylinder block (as viewed from the front).

No sign of this on my engine, instead there's an Allen stud screwed into the block in the approximate location of the expected drain. I'm assuming that the drain plug would usually screw into the engine at that point. However I've tried to remove this using a reasonable amount of force (7inch ratchet driving an Allen fitting) and it shows no sign of budging.

Before I apply even more force, I thought it would be worth checking with the enlightened company here abouts. Am I removing the right thing? If not, where is the fresh water drain located. Any other tips to drain the fresh water (to allow replacement of antifreeze and rust inhibitor)?

 

[Cloven]

I also have a Yanmar 2GM20F. There are two freshwater drain tubes on the starboard side of the engine close the fuel pump. They both have a knurled knob attached to a plastic tube which leads down below the engine. One is located higher up on the engine than the other.

Opening these should allow water to drain into the sump. From memory, the last time I did it, I got very little water from one of the tubes and lots from the other - can't remember which way round it was.

Hope this helps

 

[davel]

Hi Dave and thanks for the reply.
Looking at the service manual I can see the drain plugs you're referring to - they're on the heat exchanger. It looks like one is salt water and one is fresh.
The fresh won't drain the entire block but should suffice (with a couple of refill/empty cycles) to clear out the old antifreeze prior to replacement.

 

[Cloven]

Yes - those are the ones I was referring to. I'm sure now it was the upper (freshwater) one that produced the most water as would be expected. As you say, I just drained what was there, flushed through with plenty of fresh water and then refilled with antifreeze mix. No problems.

Dave