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Old 02-06-2021, 05:34   #1
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Yanmar Exhaust Muffler help

Hi All hoping someone can help me. I just discovered a pinhole leak in my muffler and want to replace it. I have a Yanmar 3gm30f with an exhaust that exits above the water line in the stern (though it does sink down if we are running at speed). It seems simple enough to replace the muffler. My current one is stainless but it seems like most replacements I can find are made of some composite. Would it be suitable to use this as a replacement, the dimensions look the same.

https://marinepartssource.com/2-vern...CABEgKKePD_BwE

Also does anyone know if the exhaust inside diameter is 2 inch. It appears as though it is and the outside diameter of the exhaust hose is just under 2.5 inches. Hoping to have parts in hand before I start taking things apart.

Thanks!
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Old 02-06-2021, 05:53   #2
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Re: Yanmar Exhaust Muffler help

I can't help you on the diameters, other than to say that a good vernier caliper is worth its weight in stainless steel. It's the number one item to grab before I head for the hardware store.

Mufflers can be substituted. Not a problem. In general the diameter will determine the suitability, but be aware that the same size muffler can have different muffling characteristics. You can go from throaty roar to meow in mufflers for the same engine. My mufflers come in industrial, residental, and hospital grades. There is, of course, a difference in back pressure among them.
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Old 02-06-2021, 06:11   #3
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Re: Yanmar Exhaust Muffler help

Thanks. I also confirmed the inside diameter is 2inches. I didn’t think to look at the outlet for the heat exchanger as a accessible place to measure.
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Old 02-06-2021, 06:18   #4
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Re: Yanmar Exhaust Muffler help

The water lift you linked to is a viable replacement, but be aware that it needs to be installed in the correct orientation to work properly.
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Old 02-06-2021, 07:41   #5
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Re: Yanmar Exhaust Muffler help

There is a relation between muffler volume and exhaust hose volume, but I am not aware of the exact relation. Maybe worth checking. I think the volume of the muffler must be capable of containing the backflow volume of the exhaust hose to the transom.
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Old 02-06-2021, 08:20   #6
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Re: Yanmar Exhaust Muffler help

Quote:
Originally Posted by SurlySailor View Post
Hi All hoping someone can help me. I just discovered a pinhole leak in my muffler and want to replace it. I have a Yanmar 3gm30f with an exhaust that exits above the water line in the stern (though it does sink down if we are running at speed). It seems simple enough to replace the muffler. My current one is stainless but it seems like most replacements I can find are made of some composite. Would it be suitable to use this as a replacement, the dimensions look the same.

https://marinepartssource.com/2-vern...CABEgKKePD_BwE

Also does anyone know if the exhaust inside diameter is 2 inch. It appears as though it is and the outside diameter of the exhaust hose is just under 2.5 inches. Hoping to have parts in hand before I start taking things apart.

Thanks!
Yes use the Vernalift. Good mufflers for decades. It's a form of fiberglass with special resin. In a perfect world you want enough muffler volume to hold as much water volume as can be in the hose aft of the muffler.
There is about .16 gallons in a ft of 2" ID hose.
You should have a loop up , then down in the hose near the transom before it exits.... even if the exit is above the waterline.
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Old 02-06-2021, 09:00   #7
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Re: Yanmar Exhaust Muffler help

Now that you got your use out of the metal ones get a fiberglass one and never worry about it again.
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