Yanmar 3YM30 coolant drain plug question

[Vegas]

See the drain plug, circled "B" on the diagram. How do you pull that out? Is it threaded? If so I don't see a screwdriver slot in it..... or do you simply pry it out with a screwdriver? The metal clip that seems to be holding it has deteriorated. Can I replace it with a small radiator hose clamp?

This came up as I am troubleshooting my first ever "hot engine" alarm.

 

[Roland5048]

There's an Allen set screw in there. Get your Allen set and unscrew it.

 

[Vegas]

Excellent, Roland. Thank you!

 

[SFS]

That hose can become clogged with sand, etc. The only time I have ever had reduced flow of exhaust water, I shut down and anchored, disconnected that hose at the pump, and found I had no water from the thru-hull. I cleared a LOT of sand from the hose, using (very judiciously) a long screwdriver.

 

[Scott B]

There is also a seawater drain cock on the engine block at the back of the heat exchanger. In my manual it is under "Before you Operate" section.

 

[Vegas]

Thank you! I'll try it when I get back to the boat this weekend.

I hadn't seen the "allen wrench" configuration on the bottom of the plug.....guess I better wear my reading glasses next time!!

 

[Roland5048]

I hadn't seen the "allen wrench" configuration on the bottom of the plug.....guess I better wear my reading glasses next time!!

I missed it the first time. It's quite small. Needed my cheaters.

 

[BigEasy]

It is a metric size Allen wrench. Just drained & flushed my entire system a few weekl ago!

 

[Slider]

Just a note! when trying to open the drain the plug insert turned in the hose,so was unable to get the plug out. Use pliers to hold the hose and exert extra pressure to allow the set screw to come out with the allen wrench. Job done!