Yanmar Leaking

[johnmc618]

Hello all,

New sailboat owner here. I noticed any time I turn on the Yan Marr 9 hp diesel engine, there is water spraying out of the back. I tried to film and see where the waters coming from. Anyone have any experience with this or can point me in the right direction? Any help appreciated.


https://youtu.be/5AjfOphIqJA

[Key Wester]

As I recall, there is a water jacket drain plug in that area. It either rotted out, or fell out.
I think it's a 1/4" pipe plug. Joe D

[johnmc618]

Originally Posted by Key Wester

As I recall, there is a water jacket drain plug in that area. It either rotted out, or fell out.
I think it's a 1/4" pipe plug. Joe D

Thank you. I will look for this!

[Wotname]

There is also a zinc anode plug in this area (block anode).

[johnmc618]

So still stuck on this. There is an opening from which air and water are spewing out. The opening is covered by a thing metallic cover about the size of a half dollar. It is in a very difficult to access area on the rear of the engine. The cover moves open/closed very easily with my finger, but I cannot remove it.

I need someone to point me in the right direction. All of the diagrams I find online do not list this part/area.

[Key Wester]

I have the Yanmar workshop manual here. Send your regular email address and I will send a picture of the workshop page. Do you have a model 1GM or a 1GM10? Joe D

[Westcliffe01]

See location of anode on rear of engine per shop manual

[johnmc618]

Originally Posted by Westcliffe01

See location of anode on rear of engine per shop manual

It seems to be just below this. I’ve tried taking a better video but I can’t seem to get it. I’ve marked the area in red.

[Rob_P]

Originally Posted by johnmc618

It seems to be just below this. I’ve tried taking a better video but I can’t seem to get it. I’ve marked the area in red.

Get a mirror and take a picture of the place the water is coming out. The engine doesn't have to be running to take the pic, just have good lighting on the location.

I'm thinking it's a rotted core plug leaking. That's the only thing I can think of that would be in the red marked location.

[johnmc618]

Originally Posted by Rob_P

Get a mirror and take a picture of the place the water is coming out. The engine doesn't have to be running to take the pic, just have good lighting on the location.

I'm thinking it's a rotted core plug leaking. That's the only thing I can think of that would be in the red marked location.

I can’t take a picture right now, but yes, after googling it, it seems like it is a core plug! Is this something I can fix myself, or do I need an actual diesel mechanic?

[Nineteen]

Hi
Looks like it might be on the gasket line for the head gasket from what I can see. If it is, then you will need to remove the cylinder head and find out why.
Just some good still photos would help.
Cheers
Tom

[Wotname]

johnmc618, you be able to see better if you remove the air filter (and housing) and perhaps the fuel filter.

This engine has a 'freeze' plug or cup at the rear of the block and this might have let go if the engine has been subjected to freezing temperature (without having taken the necessary freezing precautions).

[johnmc618]

Originally Posted by Wotname

johnmc618, you be able to see better if you remove the air filter (and housing) and perhaps the fuel filter.

This engine has a 'freeze' plug or cup at the rear of the block and this might have let go if the engine has been subjected to freezing temperature (without having taken the necessary freezing precautions).

I’m thinking this must be it. Unfortunately work is going to keep me away from the boat for a few weeks. But I live here in Texas where we just had freezing temps for several days, so this must be it.

Thank you all! I’ll report back.

[johnmc618]

Following up on my original post. Maybe someone will run into this problem years down the way, do a search, and find this.


So, I eventually discovered that the piece that had come loose and was allowing water to spew forth from the engine while running was the freeze plug. It makes sense, as we had had a significant prolonged freeze here just weeks before I noticed the leak. For my boat and the way the engine is situated, this freeze plug was difficult to access, so my pictures/videos are poor. I had to remove the air filter to get access to the plug.



I removed the freeze plug and took it down to Autozone where they had a replacement for about 60 cents. I purchased some "Gasket Maker" ( https://www.amazon.com/gp/product/B0002UEN1A/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 ).


This picture shows the location of the freeze plug with it removed:







At this point I applied some 'gasket maker' along the edge of the freeze plug and pushed it in by hand. I then used a socket, slightly smaller than the diameter of the plug, and a mallet to gently tap the plug into place. I stopped when the plug was flush with the outside of the engine.


This picture shows the plug in place:




I then waited 24 hours as recommended by the gasket maker substance. Started the engine up and no more leak!


Video of engine Yanmar 1GM10 running without leak:


https://streamable.com/1u8jid

[Wotname]

Thanks for the update, good outcome!