Exhaust anti-siphon hose

Kenneth K

Sustaining Member
Blogs Author
Yeah, from bigd14's picture, there is a lot more water coming from that "siphon vent" than I would have thought. Apparently, then, the line serves two purposes: an air vent (siphon break) when the engine is off, and a water vent (some have called it a raw-water bypass, I think) when the engine is on.
 

footrope

Contributing Partner
Blogs Author
Yeah, from bigd14's picture, there is a lot more water coming from that "siphon vent" than I would have thought. Apparently, then, the line serves two purposes: an air vent (siphon break) when the engine is off, and a water vent (some have called it a raw-water bypass, I think) when the engine is on.
It makes me wonder what would happen if I blocked the regular seawater hose that connects to the engine exhaust mixing elbow and check out what the exhaust water situation looks like from that little hose. It should not have the irregular chug of water that we all like to see after starting the engine. I think of the teed section as a bypass as Kenneth suggests. I have a tee and a hose configuration rather than a vented loop in my seawater cooling plumbing.

And this thread may be comparing apples and oranges to some extent since there are at least 32, 35 and 38 owners contributing information. Each of us has to figure out if our engine and/or exhaust system is above the waterline, below, or somewhere half-way. Then we can decide, perhaps with professional help, whether our configuration is suitable and safe for our uses of the boat. I have a muffler about the size and shape of a 3 lb. coffee can. It has been performing well. It has 2" diameter ports. And my exhaust system is fairly simple, perhaps because of the spacious area aft of the engine. My 2" diameter SS elbow is custom, but there are no other bronze or steel fittings needed until the transom.

Finally, has anyone ever seen what happens when the water-lift muffler gets "full" of water? The sound and appearance of the exhaust are very different. The irregular "chug" is gone. The exhaust looks like a fire hose output, perhaps with a little froth from the exhaust gases. The noise is louder due to the steady stream of water. The time it happened to me I scrambled back aboard and shut down immediately. Then I went into the "hole" and opened up the muffler drain cock and let the water dribble out. This doesn't do any damage to a healthy exhaust system, but it gets your attention. This happened after trying to start the engine after changing fuel filters. So, if you crank the engine a lot without getting it started, you might consider a cautionary drain of the muffler, even if all seems well when you get it running.

Great thread, but we need to be careful when comparing our boats to others' configurations.
 

Kenneth K

Sustaining Member
Blogs Author
Agreed!

Armed with what I've learned here, I know what I need to experiment with my own boat now.

I just pumped anti-freeze thru the exhaust system a few weeks ago. I think before I un-winterize, I'll pump some raw water through the system with the decompression lever held and the anti-siphon hose disconnected just to see what the water flow is like through that line on my rig.
.....a good thing to know before attempting to re-locate where the line vents.
 

Kenneth K

Sustaining Member
Blogs Author
Hey bigd14.....

Is Nomad your boat? I looked at her last spring in Vancouver. Great teak interior, cushions, and custom mattress. I also really liked the cockpit seats in the stern railing. That was the boat that got me hooked on Ericsons. Prior to that I was looking for C&Cs. Nice boat. How did you get her down to Portland?
 
On Sketcher, our 1983 Mark 3...

I studied the anti-siphon line allot. It is above the water line about 2 feet (at its highest) and then into the exhaust elbow.
Have sailed a port tack in rough seas, only thing that happens is some water coming up the starboard cockpit drain.

I feel this is a excellent design as is. Now.....underway with motor, the anti-siphon hose will have allot of water coming through it.
The design is so simple and works.

Originally the boat had a cast iron mixer and bronze back/flow valve after exhaust manifold. The back/flow flap broke off and stopped up the muffler underway.
That was exciting. Also the iron mixer would clog up with rust. Had a 2" stainless pipe with an angled pipe going towards the exhaust (used as a mixer) and got rid of the back flow valve.

It made an already simple system even better.


Hilco on sketcher
 

bigd14

Sustaining Member
Blogs Author
There was supposed to be a link to a video, but not sure it worked. That was full throttle load testing the diesel, and they anti siphon was moving quite a bit of water. On mine the tee fitting was attached to the underside of the cockpit sole so it's a downhill run all the way to the stern fitting. I am going to replace the flimsy rubber hose with something that cannot kink or be crushed. The diesel mechanic who inspected the engine agreed that this was a superior anti-siphon method.

Ken, sent you a PM with details on Nomad.
 

Curtis

Junior Member
Replacement with Vetus ASDV?

Question for y'all: what if I removed the anti-siphon loop/device in the engine space (above the engine on the stbd. side) and replaced it with a Vetus Vented Anti-Siphon Device? As I understand it, the vented anti-siphon device/loop would obviate the need to run a small diameter hose all the way to the exhaust fitting at the transom. Correct?

For clarification, this is in reference to a 1986 E38-200.

http://www.vetusmarine.com/store/p/337-Anti-Syphon-Device-w/Valve.aspx

The small diameter hose is reinforced rubber, and takes the cooling water from a higher point than the injection point into the exhaust. (Well, higher by whatever amount of room there is in the engine compartment...)
That hose wanders it's way aft to a little thruhull. This should be peeing out a small stream of water all the time the Universal diesel is running -- more when the revs are up over 2K and less at idle.

If someone disconnected it from the outlet on the boat, find that person and whack him with a winch handle. :rolleyes:

The outlet is a few inches above the transom exhaust on our boat, and ideally should be higher up yet. In our situation the shape of the sloped upper transom evidently was allowed to dictate the location...
:confused:

Cheers,
Loren
(Universal M25XP)
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Water from the "Tee" to the "Exit"

Question for y'all: what if I removed the anti-siphon loop/device in the engine space (above the engine on the stbd. side) and replaced it with a Vetus Vented Anti-Siphon Device? As I understand it, the vented anti-siphon device/loop would obviate the need to run a small diameter hose all the way to the exhaust fitting at the transom. Correct?

For clarification, this is in reference to a 1986 E38-200.

http://www.vetusmarine.com/store/p/337-Anti-Syphon-Device-w/Valve.aspx

I do not believe that this additional valving is needed, and also suspect that the constant flow of warm sea water thru it would probably fill the little check valve with salt crystals.
The factory set up, like the photo in post #28, is a great replacement example of the original and should do the job for another 25 years or so. Since there is a small flow of water thru this when the engine is running, it does need to exit overboard.

*Strictly as an aside, I know of one boat owner with a similar diesel installation that routed this little 1/4" exit fitting inside his cockpit, right above one of the big drains. He said that it made it really easy to ascertain whether cooling water was moving thru the exhaust system immediately when he started up his engine (his wet exhaust fitting outside was well under the turn of the hull and not visible from the cockpit).

So, just leave it in place, whether injecting the water into the trick-designed metal exhaust thru hull, or exiting the transom separately.
(*Aside #2: an E-33RH in our club had to have his original exhaust hose replaced years ago when it partly plugged due to the inner liner separating. The sound of the exhaust was interesting, to say the least! The boatyard, with his compliance, replaced the old transom fitting and put the new 1/4" hose outlet way up on the side by the transom.... it pees out onto the dock when the engine starts up... humorous and startling if you are not expecting it!)
:)

What with a thousand-plus Universal diesel installations in a wide variety of boat sizes, I suspect that EY and Universal/Westerbeke had designed a good workable solution.

Starting from scratch, I certainly doubt that I could improve on it. :nerd:

Regards,
Loren
 

David Grimm

Squid!
Just an added thought to this old thread, exhaust psyphon vents should be vented overboard. Reason being is that a one way check valve can deteriorat and fail if water stops flowing allowing exhaust gas to enter the vessel.
 

David Grimm

Squid!
This old brass 3/8 fitting is what I had off the heat exchanger. Not proper and very restrictive. The plastic one was given to me by the marina mechanic. He said it would work fine. After close inspection It would have in fact flooded the boat due to a corroded cracked rubber check valve. The final product is what I made from parts at Home Depot 3/4 with proper 5/8 hose barbs. $65 bucks.
 

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