[C320-list] Engine anti-syphon

[David Wellerstein via C320-list]

Hey C320 Geniuses!

My engine mechanic has been pestering me to raise the boat’s engine anti-syphon quite a bit higher and relocate it to the port side of the rear engine cover (the one in the aft stateroom). He says it’s way too low to the waterline (only about 3 inches above) and could backfill in particular conditions on the SF Bay. He believes this is a design flaw that was probably fixed in later boats.

I don’t have a quote yet but it’s not just a matter of buying and installing a longer length of hose. I’m not sure why that is but I do trust Chuck (IYKYK) but he does have a reputation for being meticulous and detailed, both are good traits for a diesel mechanic IMHO.

Thoughts? We do have an early boat (#118) so I wouldn’t be surprised if it is something they improved upon in later years.

Thanks as always!

David
C320 #118 “Dream Catcher”

P.S. Ordered the non-permanent Dinghy Rings Flex for our inflatable. I’ll provide feedback after I get it on board.

David Wellerstein | dwel...@mac.com | 925.301.6581 (m)

[Richard Walker via C320-list]

Hi Dave

More than 1000 these boats have been made and I have never heard in all of the 25 years that I’ve been on this chat that Edye body had a problem. The main thing is make sure it’s cleaned out every year or so.


Dick Walker

> On Jul 1, 2025, at 13:46, David Wellerstein via C320-list <c320...@lists.catalina320.com> wrote:
>
> Hey C320 Geniuses!

[Greg Arnold via C320-list]

Where is your anti-siphon fitting located?

[Troy Dunn via C320-list]

David-

Can you describe the current location in the boat of your antisiphon for
the raw water loop? I can’t speak for the oldest hulls like yours, but on
the newer hulls the anti-siphon is located in the cockpit locker and it is
quite a bit higher than the waterline, almost to the rubrail. I find it
odd that you have an anti siphon only 3 inches above the waterline. That
almost sounds like the previous owner or broker did some creative
maintenance to sell the boat. The hoses are quite expensive these days.

Maybe someone that has another early model hull can provide feedback on
where their antisiphon is located.

As for your mechanic…he isn’t wrong, three inches feels like not high
enough above the waterline. I am scratching my head as to why this isn’t
a simple fix of buying longer hoses and moving the anti siphon to the
cockpit locker. this would not be something you need to pay a diesel
engine specialist to do.

One possible reason your mechanic is saying this is complicated could be
your shallow bilge and perhaps a general thought that routing hoses to a
better location (like the cockpit locker) would require cutting into the
boat in areas that will need to be patched to prevent water damage. This
is another reason to find out if your hull has had some creative
maintenance. Maybe the routing holes and mounting holes are already
there…..I have never looked at a shallow bilge 320.

Definitely put more effort into figuring out what’s really going on here.
If this is a matter of buying new hoses and running them to the cockpit
locker….i see no reason to pay someone for this work. Unless of course you
don’t have anything better to spend this months boat buck on…

Regards

Troy Dunn
Hull #514

[Dave Hupe via C320-list]

I have hull #32.  My anti-siphon is located in the engine compartment essentially as high as reasonable on the port wall (about equal to the top of the engine).  I have never had any issues except when I bought the boat in 2017 and the anti-siphon leaked (just simply needed another duck bill rubber valve insert). 
I agree with Troy, if your valve is lower, it is just a matter of replacing a couple simple hoses and shifting the anti-siphon higher on the engine compartment wall. To move it now into the port lazzerette would require a lot more work. Newer boats indeed were built that way, but I have not experienced a problem or heard from other older model boat owners that it caused an issue.
Dave Hupe 
1994 C320 #32

Yahoo Mail: Search, Organize, Conquer

On Tue, Jul 1, 2025 at 7:15 PM, Troy Dunn via C320-list<c320...@lists.catalina320.com> wrote: David-

[Greg Arnold via C320-list]

Keep in mind that if the impeller in the raw water pump has all its
blades, water can't flow through the system when the engine is off.

Also, to establish a siphon, the end of the raw hose at the engine must
be lower than the water level outside the boat.  On my boat, the raw
water hose at the engine ends at the injection elbow, which from memory
will always be well above the water line.  So I didn't think it is
possible to have a siphon problem.

Regarding the location of the anti-siphon valve -- on my boat (2005
#1054), it is mounted on the hull in the port cockpit locker, maybe 6"
to a foot below the deck.  On a starboard tack with the boat really
healing, the valve could be below the water line.

[Dan Petticord via C320-list]

We have hull #132, and our anti siphon valve for the engine is in the
engine compartment mounted on the forward port side a few inches above the
height of the heat exchanger. The boat would be heeled over 45 degrees or
so before it was under the waterline. I also think moving it is a simple
repair (having done it for convenience sake on our old O’Day 28.). It is
just a matter of rerouting some hose runs. I wouldn’t pay a diesel
mechanic to do it, and I am very far from a confident mechanical DIYer

Dan Petticord