On Fri, 20 Jul 2007 15:59:50 -0500, Geoff Schultz
wrote:

I have a Next Generation (NextGen) 3.5 KW generator on BlueJacket. It has
an exhaust mixing elbow that combines the raw cooling water with the
exhaust and that flows into the muffler. You can see a picture of it at
http://www.geoffschultz.org/Ebay/Exhaust_Elbow.jpg

In theory this works well, but in practice, there are some severe problems.
The elbow develops internal leaks and raw cooling water can drip back into
the engine. I've been through 3 elbows and had to rebuild the engine once
due to a leak. I met other boats who have the same problems.

My plan is to replace the existing mixing elbow with a dry stack.
Basically I'll cut off the big round can and replace it with a 10" high
stainless tube U that will have the raw water entering 1/2 down the side
that connects to the muffler. I'll wrap the whole thing in insulation to
reduce the burn potential and heat.

Does this sound like a reasonable solution to this problem?

-- Geoff

You can do that and it will work fine. The portion of the manifold
before the water is injected will be HOT so be sure there is some
clearance around it even though it is wrapped.

The way I build mine is to build the "U" and then mount the raw water
inlet near the top of the manifold but with the inlet pipe angled
downward toward the outlet end of the manifold. I also weld in a
threaded nipple at the low point of the manifold and mount a gate
valve there. When I shut down the engine I open the valve which (1)
drains any residual water and (2) keeps any water that subsequently
enters the exhaust out of the engine. It is probably over kill but on
the other hand I haven't gotten any water in the engine...


Bruce in Bangkok
(brucepaigeatgmaildotcom)

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