Cape Dory Anti Siphon Installation

[Khaos13]

Hi. I've finally got the old, seized Westerbeke W21A running. I still haven't connected the sea water cooling hoses so it's only run a few minutes at a time.

Trying to reconnect the raw water hoses I noticed they're different sizes. The hose from the seacock to the pump is 3/4" but the hose barbs at the pump discharge and at the heat exchanger are definitely 7/8". The others are all 3/4". It makes installing the anti siphon a mystery; I haven't seen one in 7/8. I can change the threaded fitting on the pump but the HX port is soldered in. I guess I can remove the HX and solder or braze a threaded 3/4 brass fitting on but what a PITA.

My question is this: Did Westerbeke do this because they didn't spec the heat exchanger correctly or maybe my HX was replaced? It sucks when you have different size hoses in the same run. It will ALL be 3/4"....eventually.

BTW, the Cape Dory forum is down for updates and that hose is EXPENSIVE!

[Khaos13]

I have to be honest here... it's been about a year since I pulled this thing apart and my memory of how the hoses were hooked up eludes me. Because of the size discrepancies, it appears it can be only one way and that is with the anti siphon AFTER the hx and BEFORE the exhaust elbow. The exhaust elbow is so high (and almost dead center) that it seems all that extra hose is redundant. Just insert the vented loop right before the elbow. I could actually install the loop in a lazarette and make checking it easier. Am I missing something?

[skipperpete]

Its a long time ago now but what caused your engine to originally get flooded ? Hopefully not because of the siphon break.

[GordMay]

Dave Gerr’s “Boat Mechanical Systems Handbook”
Ch 7 Wet Exhaust Systems ➥ https://issuhub.com/view/index?id=10037&pageIndex=126

[Khaos13]

GordMay Thank You!!!

I downloaded this excellent resource:
Dave Gerr’s “Boat Mechanical Systems Handbook”
Ch 7 Wet Exhaust Systems ➥ https://issuhub.com/view/index?id=10037&pageIndex=126

Lots of answers to questions I haven't even thought of yet!

[Khaos13]

It's all back together and running pretty well. Seawater pumping great and the anti siphon, though not perfect, is functional. No working gauges so I'm reluctant to let it run too long. Hooking up new gauges, alarm, alternator, etc... still need sorting out. I'm thrilled that this thing is running again. I consider it a miracle. This forum is so awesome!

[Orion Jim]

https://www.westerbeke.com/advanced%...s/w21_w21a.pdf

There is a diagram contained here which shows their intended anti-siphon installation.

https://www.westerbeke.com/technical...hnical_man.pdf

https://www.westerbeke.com/operator'...ner_manual.pdf

The service manual and the operators manual which came from the Westerbeke website.

[Khaos13]

Thank you Orion Jim. That diagram says it all. Nice to know there are still a few W21 owners out there.

[gonesail]

a little late here but i looked at my boat. the anti siphon valve is up in the area between the cockpit and bulkhead behind the electrical panel. i could get a picture if you need it.

[Khaos13]

Thank you gonesail. Nice to know where it's supposed to be. I have not secured it yet but it's OK. I'm trying to get the gauges working now so I can take it out for a spin. Not going well. Might have to PM GordMay.