Yanmar mixing elbow gasket

Mar 9, 2016
8
Beneteau Oceanis 352 Port Moody, B.C.
Hi
I have a water leak at the discharge of the Yanmar heat exchanger, at the mixing elbow. I purchased a new gasket, but looking at the face of flange, it has some pitting and corrosion (see attached photo). I think if I put the new gasket on, its still going to leak. Does this need to be resurfaced (if so - how?) or is there some kind of compound that can be put on with the gasket that will seal that area.
thanks
Dan
 

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Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Dan, if memory serves me right, place the new gasket on the flange face and you'll see that the corroded area doesn't touch the gasket material. That's why it's corroded as it's not covered by the gasket material. The bolt holes position the gasket. I currently have mine apart and it's sitting on the boat. I'll be up working on it on the weekend and will reply to let you know if that's not the case.
 

NYSail

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Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
Clean the entire area good, get all of the old gasket off and you should be fine....
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Of note: That gasket should not be able to cause a water leak, it seals the exhaust gas only.. water in that area would be from the round heat exchanger cover just above, or from the hose connection/hose that carries the water from the cover to the mixing elbow.. There is a goo that will work there, Permatex® #26B, but from the looks of the face, it would not be necessary.
Ralph is right on.. .. clean the surface being careful not to scratch it as NY SAIL says.
 
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Likes: Gunni
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
Claude makes a very good point. There should not be water at the gasket. If the water is from above (more than likely) like he suggests, the problem is minor. If it's coming from inside the riser manifold you could possibly destroy your engine. It would suggest that the mixing elbow has corroded thru and leaking backwards to the exhaust manifold and possibly into the engine.
Don't let my poorly written post freak you out. Just be sure and find out where the leak is coming from!
 
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Likes: kloudie1
Mar 9, 2016
8
Beneteau Oceanis 352 Port Moody, B.C.
Thanks everyone! I will definitely look into the source of the water. As far as I can tell it is from inside...
Dan
 

NYSail

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Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
Ha exactly right.... this is gas only side. Water is after unless mixing elbow failed or starting problems flooding back water. Engine will die if water is there.
 
Mar 9, 2016
8
Beneteau Oceanis 352 Port Moody, B.C.
Well.
I put it all back together, fired it up, and ....water dripping. So I took a closer look - there's a tiny crack (corrosion) on the outside, where the pipe meets the plate. I think I can just get it welded up and should be OK? A new mixing elbow is $343CDN!
 

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NYSail

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Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
Thinking there is another issue. Why would water be there.....
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
keep looking for the water source - that crack isn't it use chalk or dry erase markers up-hill of where the drip is showing up.
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
You have bigger problems than a crack. There should not be water coming out of there.
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
So I took a closer look - there's a tiny crack (corrosion) on the outside, where the pipe meets the plate
Dan, I would suggest a full stop and go no further. To echo everyone else here, YOU HAVE A PROBLEM WHICH IS GOING TO DESTROY YOUR ENGINE AND VERY QUICKLY.

The leak you photographed is going to save your engine, but only if you heed what it's telling you. There is no relation between the leak you are seeing at the base (where it's welded to the flange) and the leak which is allowing the sea water to get to where it shouldn't be.

Sorry I didn't get back to you sooner as mentioned above but after looking at the connection between the riser and the exhaust manifold on my setup, they are similar to what you show with the different sized openings.

I see that you have a different mixing elbow from Yanmar's usual setup:

Mixing Elbow Assembled With Directions 3.JPG


Taking a look inside a mixing elbow:

Cleaned Sectioned Mixing Elbow R.JPG


............. you can see that there is no way water can get back to the riser unless you have a leak through the thick wall that separates the sea water from the exhaust gasses. And if that happens :yikes: :banghead:. Although the shape of your mixing elbow is different, the principle is the same.

I notice that your mixing elbow is fabricated from SS plate and tubing. You might want to go with a cast iron one from Stem to Stern. Others have sworn by a cast 316 SS one like this:

Exhaust Elbow SS.JPG


I've never tried the SS one because the cast iron one gives reasonable service HOWEVER it is twice the price. Any way you look at it, the cost of a new elbow is peanuts compared to what sea water does to your cylinders.
 
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