Exhaust anti-siphon hose

Cory B

Member III
Hello,

Ours (and most 80s-vintage Ericsons?) have a funky antisiphon hose coming off the exhaust thruhull. It is above the standing water line, but sometimes below the sailing one. Ours is made of a small rubber hose that does not appear to be rated for exhaust or anything, but most troubling, is that it ends in the lazarette about cockpit floor level, with a bolt jammed in the end! I'm certain this isn't right.

So, I'm curious to hear how other boats have this hose terminated. We're thinking of replacing the hose with A1 rated fuel hose, and T-ing it into a vent we have located on the outside of the cockpit combings just below the winch. The vent is currently used for the PSS vent line, and I don't see any problems sharing them. Does this sound reasonable?

Heres a pic of the exhaust fitting in the aft lazarette for anyone who doesn't have this and is curious about what the h*ll I'm talking about.
 

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treilley

Sustaining Partner
I don't think mine has that. But I will have to confirm. I think my exhaust hose runs high in the stbd sail locker with no vent. My thru-hull is Marelon. That may have been added after the fact.
 

Cory B

Member III
Interesting. The anti-siphon hose is mentioned in the 35-3 manual, so I think its original. The highest point of our exhaust hose is just under the cockpit floor, not up into the locker. I'd imagine going up to the top of the locker would remove any need for the hose.
 

John Bouchard

Member II
Ant-siphon

I'm sure I don't know what the H*ll I'm talking about, but I'd just take the bolt out of the end of the small hose and fix the end as high up as you can. You could also (but probably not necessary) install a small anti-siphon valve in the end of the hose.

Looking closely at the picture, it almost looks like the bronze/copper tube is crimped just before the plastic hose?

I don't have such an exhaust outlet hose with shutoff on my E32 (Atomic 4), so I'm just guessing here!:confused:
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
It's a Universal Diesel thing...

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)
 
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Cory B

Member III
Hi John,

Its actually not crimped, but the hose "barb" is just really really long.

I thought about just putting it high in the lazarette, but since its connected to the exhaust line I was worried about getting fumes in there, hence my thinking of running it outside the hull. I'm kinda wondering if someone put the bolt in the end just to stop the fumes.

On our previous boat (an E32 with an A4 like yours) the exhaust was ran high in the lazarette. We could do the same with this boat, but lazarette space is at premium, since I think it may be a little smaller than what we had in the E32 (I could make a list of things that were "better" in the 1975 E32 than the 1984 E35 :) )
 

Gary Peterson

Marine Guy
I believe that small hose is supposed to go from the dripless shaft seal to the exhaust outlet at the transom. It removes trapped air behind the seal when you are motoring in forward. I don't think any other line is supposed to be T'd into it. My 381 with a dripless seal has the line directly from the seal to the transom exhaust outlet.
Larger, faster sportsfisherman yachts feed transmission cooler water to this seal to delete any air in the seal and to keep it lubricated.
 

Cory B

Member III
Gary,
The two are unrelated. The anti-siphon hose was OEM and I installed the PSS when I bought the boat. You did make think about just directly connecting the two for a moment, but I don't think its a good idea, unless there is a "vent" somewhere in the middle (which is what I was originally considering). Having vent lines for two different things below the sailing waterline just doesn't sound good to me - it seems like it would defeat the purpose of the exhaust anti-siphon.
 
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Steve

Member III
Same on our boat

Cory

Can't get to the boat until next week, if by chance this isn't rectified by then, I will take some pictures. Our 35-3 has the same set-up, it's attached on the other end to the high end of the loop of the raw water final circuit, run up in that small recess between the cockpit and the stair area above the engine. At lease this is what I recall now... I'll confirm next week if we need.

The only photo I found today was an older one of the engine in general, it's the darker hose off the heat exchanger headed up into a loop then back down to the exhaust. The little hose comes off the top of that loop. I've since put noise dampening material in and changed a few other things around.

Steve
84 e35-3
 

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rwthomas1

Sustaining Partner
FWIW, on my E38 that little rubber hose runs from the bronze exhaust elbow just as yours does to the vent at the top of the anti-siphon loop/device in the engine space, just above the engine on the Stbd. side. The exhaust hose is also led quite high, to almost the top of the cockpit locker lid, then back down and to the transom. RT
 

newgringo

Member III
We have something almost identical in our E32-3. The small hose originates at a seawater line Tee just under the cockpit floor directly above the heat exchanger. The Tee is plumbed in between the heat exchanger seawater outlet and where it dumps seawater into the exhaust elbow. It terminates near where the exhaust exits the stern of the boat. I believe it has something to do as an anti siphon device. Might pay to read up on anti siphon requirements for your engine installation. Could be pretty important.
 

Cory B

Member III
Consensus

Thanks for the responses.

So the consensus is that originally there was a tee of some sort off the raw cooling water with a hose that ran to the exhaust fitting. That makes sense. I think a previous owner must have cut/removed the antisiphon line when they redid the exhaust system, then when they found exhaust gases coming up through the remainder of the hose they plugged it with the bolt (brilliant). Boats sure are interesting things sometimes.

I am still a little confused though why they "vented" the antisiphon line to a fitting that is sometimes below the waterline when the boats in motion. But at rest it would obviously do its job, and I haven't heard of any E-boats that have had siphon issues with their raw water cooling, so it must have worked.

I don't see how the hose could have also acted as an anti-siphon for the exhaust as I originally thought, since if it were connected to the raw water system it would have no vent to atmosphere.

I'm thinking I may just plug that hose barb fitting on the exhaust, and run a antisiphon vent line from the raw water cooling to the existing "high" vent used for the PSS.
 

newgringo

Member III
VETUS Catalog Info on Anti Siphoning

Couldn't resist looking a little more. The VETUS Marine catalog I have for 2007 on page 143 "AIR VENT" says " If the injection point of the cooling water line is situated less than 6 inches above the (boat) waterline, then - when the engine is stopped - there is a risk that, as a result of siphoning, the cooling water may enter the engine. Such siphoning may be avoided be positioning a VETUS air vent into the cooling water line, appr. 16 inches above the water line". On our E32-3 the injection point is definitely within 6 " of the waterline. And the Tee in the seawater line is not 16 " above waterline, but under the cockpit floor is about as high above waterline as practical. I guess the official opinion, of at least one manufacturer of marine engine gear thinks a vented seawater line is important. And they show the vent line from the Tee going overboard well above waterline.
 

Cory B

Member III
...And they show the vent line from the Tee going overboard well above waterline.
For the life of me I can't understand why Ericson originally went to the trouble of installing a vent line for the seawater cooling and used that funky exhaust thruhull fitting instead of using a more traditional vent that would be above the waterline when sailing. I feel like I must be missing something here, but I have no idea what.
 

rwthomas1

Sustaining Partner
The anti-siphon line breaks the vacuum and dumps the water collected into the exhaust past the elbow after the engine is shutdown. That negates any tendency to siphon. Having the anti-siphon vent line lead into the exhaust seacock makes sense. Where it is situated there is no practical way that it would "backflow" even when excessively heeled IF the exhaust hose and vent line is routed correctly.

On my boat both of these lines run high, up to the cockpit floor for the vent line and up the side of the cockpit locker for the exhaust hose. This will negate any tendency to backflow as the high point in the lines is well above the waterline at all times.

I like the idea of the vent line entering the exhaust elbow simply because there is one less thruhull above the waterline to worry about. Makes sense.

RT
 

chaco

Member III
Anti-Siphon Basics

Check out the Westerbeke Installation Manual at www.westerbeke .com
and the Vernalift Wet Exhaust Manual at www.centekindustries.com
for the best information on Wet Exhaust Basics.
The Exhaust GooseNeck is installed to drain DOWN to the Lift Station.
The recommondation is to place the Anti-Siphon Loop above the waterline
and to install the Vent above the Loop.

Hooray for Vacuum Breakers :egrin: :egrin:
 

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Gary Peterson

Marine Guy
I was in error in my post of 3/13.

I went to our boat and uncovered it to be able to go inside. I was in error when I said my shaft seal line went from the seal to the transom exhaust exit.
The seal air purge line goes up and ends under the coaming and is open to atmosphere. The anti-siphon line goes from the highest point, where it is "T'd" into the H/E out hose that goes to the water mixture elbow.
In my previous life as a marine application engineer, I was responsible for approving OEM installations, including exhaust systems, but they were somewhat different in high horsepower turbocharged marine engines in sportsfishermans. They use no vacuum breaks because the turbo outlets are at, or above, the waterline.:nerd:
Sorry for the initial misinformation:redface:
 

Steve

Member III
Here's the photos

Finally got to the boat and took some photos of the set-up today. Actually I had forgotten about this hose arrangement, really hadn't looked hard at the fitting for some time. I noticed a few chafe areas that I should protect, so some odd way.. thanks!

Steve E35-3
 

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Cory B

Member III
Thank you

Thanks for the pictures Steve. Its good to see how it was intended to be hooked together, and makes a bit more sense now.
 

mkollerjr

Member III
Blogs Author
Hi,

I was snooping around my Yanmar 3HM35F last night after replacing some coolant hoses and flushing the engine, tightening hose clamps, etc... and I noticed a few more hoses that I need to replace (the hose on the outlet of my heat exchanger appeared like it was going to pop off at any time, flooding my engine compartment with salt water!).

The "vented loop" in the photo below also appears about ready to spring a pinhole leak and spew salt water all over my engine.

My questions are:

1. Is this truly a vented loop, with an air-addmitance valve, such as this? http://www.westmarine.com/buy/forespar--vented-loop-cap-marelon--594127?cm_mmc=PS-_-Google-_-Shopping_PLAs-_-594127&adpos=1o1&creative=54604249924&device=c&matchtype=&network=g&gclid=COfPy5jmyMQCFY-HaQod_ZkAoQ

2. ...or is it just two elbows and a tee?

3. Any suggestions on a replacement?

IMG_2070.jpgIMG_2071.jpg

Thanks,
Mark
 
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