James, do you think that little anti-siphon valve would keep up with the water pump??? It is there to prevent siphoning not back flow.Nope.
It has to be higher than your high point vent on the sea water pump.
That is there to prevent back flow on engine shut down.
Recipe for disaster. Assuming it never fails, gets clogged (and fails) or disintegrates from the heat (another fail cause).Back flow preventer?
That's right, and silence the exhaust. The raw water cools everything starting at the injection elbow and everything downstream. An inch or 3 settles in the base of your muffler as exhaust pressure forces plugs of water out of the muffler(which almost eliminates the exhaust sound), and through the rubber exhaust hose.So, here’s another dumb question: why does the raw water that goes through the heat exchanger get pumped into the exhaust system? Why not just send it overboard separately? Is it just to cool the exhaust?
Reflect on two hydraulic situations...on further reflection that valve is only open in vacuum conditions
That was me, Leslie. In fact, they used to build wet exhaust systems that didn't have this exact problem.Yes, I have seen an Alden iirc, that had concentric copper exhaust, water in outside annulus, exhaust on the inside. Sounds like maintenance nightmare but new owner worried cut a section open and good as new.
So, here’s another dumb question: why does the raw water that goes through the heat exchanger get pumped into the exhaust system? Why not just send it overboard separately? Is it just to cool the exhaust?
Yes. The water cools the exhaust gases which are around 1K*. Cooling the exhaust allows the use of synthetic/rubber hoses which makes it easier to run the exhaust out of the boat. The water lift muffler helps to dampen the sound of the motor, which makes motoring for longer distances more tolerable.That's right, and silence the exhaust. The raw water cools everything starting at the injection elbow and everything downstream. An inch or 3 settles in the base of your muffler as exhaust pressure forces plugs of water out of the muffler(which almost eliminates the exhaust sound), and through the rubber exhaust hose.
sorry for spelling. first of all you should find out, if you are in danger. do you have raiser or not, is your wet ehsost water inlet higher, then muffler and ehsost outlet. if you are not sure, test is simple: disconect exhost hose from engine elbow or raiser and try to fill it with water(hose or bukket). if it fills, you in danger, if drains out-nothing to worry about.So, naturally I am trying to work out in my head if there is a design to prevent this.
Some people install a seacock valve on the exhaust throughhull, especially, if they use the boat for long off-shore passages. Of course, the trick is to remember to open it, when you want to use the engine.Nope.
When I checked my exhaust system elevations out, I found that my boat would "slosh back" the water seal into my not running engine, in a near bow on sea state of 2-4 feet.
Well that would be like the...Some people install a seacock valve on the exhaust throughhull
True. From what I read, on long passages, people were having problems with following seas pushing water into the muffler. So the seacock was not to prevent the remnants of the water in the muffler from sloshing back into the engine, but to prevent more sea water entering the muffler from behind.Well that would be like the...
"Banana in the tail pipe" trick.
I suggested that my forum post, but no one responded.you might need to drain the muffler for a long passage. A major PITA, I imagine.
A seacock in the exhaust might still help prevent the water from sloshing backwards from the muffler as well. If the exhaust line is closed then no air can enter the muffler from the back, so a column of water won't be able to go towards the engine without generating suction in the muffler. That suction would stop the slosh, unless it wasn't a full column in the line between the elbow and the muffler.True. From what I read, on long passages, people were having problems with following seas pushing water into the muffler. So the seacock was not to prevent the remnants of the water in the muffler from sloshing back into the engine, but to prevent more sea water entering the muffler from behind.
In order to prevent your problem (sloshing water from the muffler entering the engine), you might need to drain the muffler for a long passage. A major PITA, I imagine.
@markwbirdWow! Thank you for gracing my post with your knowledge and wisdom, Stu The Engineer. In addition to all of your knowledge about diesel engines I think you really nailed the tone I was looking for in a response. Thanks, again.
When I designed my system, for that reason - volume - I went with a larger capacity water-lift muffler. As a typical old CCA design, the 'resting' volume of raw water is at a max. The extra volume keeps all the flow back in the bottom of the muffler.The total volume of a wet exhaust system (muffler/hose), and the rise to the intake manifold should be more than adequate to handle coolant water, for any reasonable pitch angle of the boat. Offshore we have a couple of nerf footballs which fit the thru-hull exhaust port nicely. That is a $2 fix.