Anti-siphon valve on engine

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rjengelhart
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Anti-siphon valve on engine

Post by rjengelhart »

Ref: pg 55A of Owners' Manual
Hi,

I've searched high & low for this valve, but can't find it? Any hints? Hull 464.

Thanks.
vr
Bob Engelhart
SV Andiamo #464
Punta Gorda, FL
wolfe10
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Re: Anti-siphon valve on engine

Post by wolfe10 »

Contact Catalina. They can tell you whether you need the kit and at least the kit for our 2003 came with very good installation instructions.

If installed, if yours is like the kit for our 2003 #180, it would be in the aft wall of the main saloon above the engine behind the stairs behind a small add-on panel. Two valves-- one for the engine raw water, the other for the PSS shaft seal cooling line.
Last edited by wolfe10 on Sun Mar 08, 2020 11:46 am, edited 1 time in total.
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
jrohrbaugh
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Re: Anti-siphon valve on engine

Post by jrohrbaugh »

Mine is just above the engine access behind the stairs. It's a loop. Shielded by a wooden cover.
Good luck.
My Hull #444.
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Captain Kirk
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Re: Anti-siphon valve on engine

Post by Captain Kirk »

Mine is located behind the companion way stairs on the forward side of the bulkhead. It is behind a (color matched) wood panel that I believe came with the kit that Catalina supplied. As I recall anti-siphon is only on the PSS seal, lube/cooling water line. I think its a 1/2" hose. The water is provided to the seal to eliminate chattering and wear of the seal faces.

The PSS seal on my previous boat (C320) did not have a lube connection point as it was an earlier version of the seal. When air collected in the shaft log, the seal was no longer lubricated or cooled and the chattering was loud- sounded like it would certainly ruin the seal quickly. The remedy was to quickly go below into aft cabin, lift the mattress up, remove the cover and then pull back on the bellows of the PSS seal to allow the air to burp out, as the sea water came in through the seal faces. Not fun but had do it regularly.
Kirk & Leah McCullough
#031 -Full Batten Main, Rocna 20
Sand Dollar
Point Roberts, WA
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Re: Anti-siphon valve on engine

Post by wolfe10 »

All of us are describing the same location.

Ours has TWO anti-siphon valves per the kit. One for engine raw water and one for PSS shaft seal. Smaller (shaft seal) valve located within the footprint of the larger one.

Lift the removable panel over the engine in the aft cabin and you should see the hoses going up to the anti-siphon valves.
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
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TBOT422
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Re: Anti-siphon valve on engine

Post by TBOT422 »

Brett,
Why would there be an anti-siphon loop on the PSS cooling line? Our PSS cooling line is just a short small hose from the seacock directly to the PSS collar. The PSS line has it's own dedicated seacock separate from the engine seacock.

While we're talking about the anti-siphon valve, If I understand correctly, if it is working properly it would prevent seawater from siphoning into the exhaust system through an open engine seacock. If the engine was not running, the exhaust valves could be open and sea water could go directly into the engine. However, what I don't understand is how one would know if it working properly at all times. I regularly take it out and check it and have never had any problems. But we did have the anti-siphon valve on the shower sump pump fail once. It is the exact same device. When the sump pump pumped out all the water in the shower and shut off, seawater flowed back into the shower and the pump would cycle on and pump it out again then sea water would flow back in again. I found the anti-siphon valve to have some debris in it. After cleaning and replacing, all worked fine. My problem is if that same scenario were to happen to the engine anti-siphon valve, I would assume the engine would be destroyed before you even knew there was a problem. If that is true, and the failure mode of the anti-siphon valve results in engine damage, it seems like there should be redundant protection of some sort.
Gary & Janet
The Best of Times (Hull #422)
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Re: Anti-siphon valve on engine

Post by wolfe10 »

I remove the "cap" on both valves a couple of times a year and clean them-- remove salt deposits. As long at the "cap" admits air in when not in use and does not leak water when in use, they are good.

Catalina Yacht Engineering Bulletin #69 sent out 12/13/2005 gives very good instructions. Bulletin says it applies to all Catalina 350's through hull 372.

The water plumbing for the PSS shaft seal is completely different, with "pressure water" from raw water pump going into a "T" with the small hose going to the new, smaller anti-siphon valve and from there to the shaft seal.

Well designed and a pretty easy installation.
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
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Captain Kirk
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Re: Anti-siphon valve on engine

Post by Captain Kirk »

I was at the boat today scoping out a planned replacement of the raw water lines. And yes the raw water line is indeed a second valve that came in the kit. So yes TWO lines and two anti-siphon loops to take care of this issue.

Hopefully we all now know where to find these anti-siphon valves and how to maintain them, with this good input from the group.
Kirk & Leah McCullough
#031 -Full Batten Main, Rocna 20
Sand Dollar
Point Roberts, WA
rjengelhart
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Re: Anti-siphon valve on engine

Post by rjengelhart »

Thanks to everybody who offered help. I'm certain the PSS does not have a valve.

I'll look more closely for a 'hidden' exhaust anti-siphon.

I have contacted Catalina, but no response yet; maybe they'll send a kit.

Again, thanks to everybody.

vr
Bob
Andiamo
Hull # 464
vr
Bob Engelhart
SV Andiamo #464
Punta Gorda, FL
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TBOT422
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Re: Anti-siphon valve on engine

Post by TBOT422 »

From the comments above, apparently earlier models of the 350 did not have the anti-siphon valve nor a dedicated cooling line for the PSS. Catalina apparently sent out an upgrade 'kit' for owners. Later models that I have seen all have a dedicated cooling line for the PSS with it's own dedicated seacock, and the exhaust anti-siphon valve is located above the engine compartment behind the companionway stairs.

What still bothers me is that apparently a little dirt in this little plastic rubber diaphragm valve could potentially destroy the engine and you might not know it until the engine failed completely. That doesn't seem to be like much protection.
Gary & Janet
The Best of Times (Hull #422)
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Re: Anti-siphon valve on engine

Post by wolfe10 »

TBOT422 wrote: Tue Mar 10, 2020 7:06 am
What still bothers me is that apparently a little dirt in this little plastic rubber diaphragm valve could potentially destroy the engine and you might not know it until the engine failed completely. That doesn't seem to be like much protection.
Kind of the nature of the beast, as all sailboats have their engine and obviously their shaft seal below waterline.
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
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Captain Kirk
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Re: Anti-siphon valve on engine

Post by Captain Kirk »

Just a heads up on the installation of these kits. Sand Dollar's kit was installed around 2004/5 by the previous owner. I've had the boat now for 4 years and never had any issues with the seal. However here is what the yard reported to me when I had them install all new raw water lines last week.

Quote

"THE WAY THE SEAL WATER LINE WAS INSTALLED WAS INCORRECT BECAUSE IT WAS ON THE SUCTION SIDE OF THE PUMP. IT SHOULD BE ON THE PRESSURE SIDE OF THE PUMP OTHERWISE YOU ARE SUCKING IN AIR THROUGH THE VENTED LOOP POTENTIALLY REDUCING YOUR COOLING. FOR BOATS THAT OPERATE AT LOWER RPM'S THEY ONLY REQUIRE YOU TO RUN THE SEAL WATER HOSE ABOVE THE BOAT'S WATER LINE AND DOES NOT REQUIRE PRESSURIZED WATER.
THE POINT OF THE LINE IN YOUR CASE IS ONLY TO REMOVE THE AIR THAT ACCUMULATES IN THE SEAL CAVITY SO YOU HAVE SEA WATER THERE AND NO AIR.
WE ONLY INSTALL THE PRESSURIZED LINE ON HIGH RPM ENGINES, USUALLY LARGER POWER BOATS." Unquote.

So I now have the seal water line reconfigured to be used only as a vent for the seal with cooling and lubrication provided by the water in the shaft log. In my past experience that will work fine. In any case the way it had been installed it was essentially only a vent line with the downside being the sucking of air through the vented loop. Having said all that, I've put on over 400 hrs with this incorrect install (with a total of 2000 hrs on the engine) and have never had any problems with the seal or with engine cooling.

Maybe we should all check that ours kits to see how they were installed. Did Catalina provide faulty instructions? Or did the PO simply install it incorrectly. At this point i'm assuming the latter.
Kirk & Leah McCullough
#031 -Full Batten Main, Rocna 20
Sand Dollar
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Re: Anti-siphon valve on engine

Post by wolfe10 »

OK, I pulled out the Catalina Engineering Bulletin Number 69 from 12/13/05.

Drawing number 53001-4 is for the engine raw water cooling siphon break and is CORRECT. Siphon break is on the pressure side, after heat exchanger and before exhaust elbow.

Drawing number 50010-3 is for the new "pressurized" water cooling for the dripless stuffing box. and is CORRECT. Siphon break is on pressure side after "T" coming off hose from the raw water pump and before the dripless stuffing box.

That is the way it should be and that is how I installed it more than a decade ago. No problem other than the occasional cleaning of the cap to remove deposits.

Agree- a siphon break on the suction side would suck air in and for the engine cooling circuit could easily lead to overheating of engine. Previous owner may have been BUBBA.
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
tmh
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Re: Anti-siphon valve on engine

Post by tmh »

I developed a water leak this weekend on the smaller loop at the top of the loop i.e. cap/valve.
I saw in this thread the good discussion so I assume this is the vented PSS shaft seal anti-siphon loop.
But I could not find out where to get a new cap/rubber valve to replace the leaking one.
Also, I do not know the size of the smaller or larger loop.
Any help on where to get a replacement cap and size of the two loops would be appreciated.
Thanks
Mike
Irish Ayes
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Re: Anti-siphon valve on engine

Post by wolfe10 »

Mike,

I pulled out the paperwork that came with our retrofit kit for the 2003.

It shows the shaft seal siphon break as Forespar Cat #0002190 FA16M which is a 1/2" model.

BUT, have you tried removing the cap and cleaning out the valve-- often they can get clogged with dirt/salt and I have often been able to unscrew them and just clean them gently with water.

This MAY be what you are looking for: https://www.forespar.com/product514.html
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
randaldonnell
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Re: Anti-siphon valve on engine

Post by randaldonnell »

This valve is critical when it comes to not destroying an engine or sinking a boat but you cannot see if it is actually working, I wish someone would invent a visual indicator for the valve. This could be sort of a check valve with a rod in a clear tube. When the rod is up, the valve is closed. When the rod is down, the valve is open. Further, once the engine is off, there could be an extension to the rod that one could push down manually (or a bulb to press) to manually open the valve if it got stuck in the closed position.

I know some sailors will close the engine thru hull and hang the engine key on it. I would prefer to be able to see the position of the valve with an indicator as mentioned. I would also like to be manually 'trip' the valve when I shut off the engine if the indicator did not show the valve in the open position.

For now, I leave the cap slightly unscrewed (1/4 turn) and when I shut off the engine I turn the cap to make sure air is introduced. Another option (and maybe better) would be to push a small wire with a rounded and smooth end down into the duck bill or use something like a turkey baster (although smaller) to push air thru the valve. Any of these options would break any siphon.

As a side note, the valve on my shower has ALWAYS stuck in the closed position even after cleaning and testing several times. I am glad this defective valve was not on my engine loop. The indication of a bad valve in the shower loop is obvious, seawater filling the shower. No such obvious indicator for the engine hence my desire for a visual indicator.

Here is a good explanation from BoatU.S. on how a duckbill anti-siphon valve works.
https://www.boatus.com/expert-advice/ex ... lve-basics
rjengelhart
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Re: Anti-siphon valve on engine

Post by rjengelhart »

Late, late, late reply. Actually found the valve last fall, but didn't log it.

Finally found the anti-siphon valve; it's located in the starboard cockpit locker.

Cleaned the cap...it was stuck a bit.

All is well.

Thanks to everybody who helped.
vr
Bob Engelhart
SV Andiamo #464
Punta Gorda, FL
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Re: Anti-siphon valve on engine

Post by FWF »

Getting acquainted with our new boat and am curious if the anti siphon is supposed to make a hissing noise. I took a video, but don’t think the site will allow it to be posted.

Fred
Fred Fallman
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Hula Kai
wolfe10
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Re: Anti-siphon valve on engine

Post by wolfe10 »

Unscrew the "tops". Soak in white vinegar/clean. Reinstall.

Easy for the "duck bill" to get clogged with minerals, especially when operated in salt water.
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
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