Anti-Syphon Leak
Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 345/348
Forum Description: 345/348 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=15040
Printed Date: 26 March 2026 at 23:50
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: Anti-Syphon Leak
Posted By: Al 348
Subject: Anti-Syphon Leak
Date Posted: 30 March 2025 at 00:40
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Dear Friends, I own a 2022 Hanse 348 with a Yanmar 3YM30 diesel engine and SD-25 sail drive. Today I recommissioned after winterization. The engine started right up with water from the exhaust exiting normally. Then I noticed water in the engine compartment coming from a small tube connected to the anti-syphon system. One tube going from the heat exchanger to the anti-syphon, then one exiting the anti-syphon to the exhaust system and one tube coming from the anti-syphon to the open basin under the engine. This is where the water was coming from. I took the anti-syphon apart. There was no debris. I took out the valve, spring, and O ring, put it all back together and the leaking became worse. Any advice? Thank you in advance. Al ------------- Peace through Sailing |
Replies:
Posted By: Arcadia
Date Posted: 30 March 2025 at 02:06
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Sounds like the valve in the anti siphon is not closing fully when under normal water pressure. It should only open when under suction. It can sometimes stick open, but that is what the spring is for. Any chance that it was reassembled wrong ? ------------- Leon / ARCADIA 2018 Hanse 588 Sag Harbor, NY |
Posted By: Al 348
Date Posted: 30 March 2025 at 02:21
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It’s possible. I wonder where I can find a diagram of the anti-syphon system. Thank you, Al ------------- Peace through Sailing |
Posted By: Arcadia
Date Posted: 30 March 2025 at 02:30
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I don’t know for sure about the 348, but Hanse usually uses the Vetus unit. Vetus may have a diagram on their website. The model is “AIRVENTV”. ------------- Leon / ARCADIA 2018 Hanse 588 Sag Harbor, NY |
Posted By: Arcadia
Date Posted: 30 March 2025 at 02:36
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Try this. https://vetus.com/wp-content/uploads/030405.04-r04-2025-03-Beluchter.pdf" rel="nofollow - https://vetus.com/wp-content/uploads/030405.04-r04-2025-03-Beluchter.pdf ------------- Leon / ARCADIA 2018 Hanse 588 Sag Harbor, NY |
Posted By: Al 348
Date Posted: 30 March 2025 at 05:18
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Thank you. The diagram confirms that is how I reassembled the anti-syphon system. It is recommended to spray the valve with Teflon spray and I will try Sailcoat and let you know if that works. Al ------------- Peace through Sailing |
Posted By: Tranquillity
Date Posted: 30 March 2025 at 18:22
| If the clear antisyphon pipe is dripping into the bilge, cleaning the valve, spring, and assembly with fresh water normally does the trick to stop the drip! However last year despite cleaning it still leaked so swapped the value and all was good again. The valve is incredibly expensive for what it is from Vectus but if you Google the part I found one for a fraction of the cost on the web. |
Posted By: Ratbasher
Date Posted: 31 March 2025 at 15:42
Leon - many thanks for the link; most valuable. This is another of those items requiring regular maintenance/replacement that aren't that well known at all, like the paddlewheel on the speed log that I discovered needed changing earlier. My maintenance log is growing all the time! Iain
------------- H400 (2008) 'Wight Leopard' Gosport, UK |
Arcadia wrote:Posted By: Al 348
Date Posted: 31 March 2025 at 20:04
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I did take the valve apart and cleaned it well with fresh water, made sure the spring and O ring were reassembled correctly as per the Vectus diagram and the leak is worse. Apparently, there is a dealer in my area that I have contacted via the Vectus website and will obtain a new valve. I will also check the web as Tranquility suggested. Thank you, Al ------------- Peace through Sailing |
Posted By: samuel
Date Posted: 01 April 2025 at 10:58
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I put the end of the small pipe into a 5 litre plastic container to collect the water drips. Then after each trip, or during a long motoring trip I just empty it down the sink. To prevent that syphoning back in to the engine when it is switched off, I have made a tiny hole in the pipe above the container level. I have the Volvo valve which is designed to drip continuously. But if the units nut is overtightened it will run quite hard. Salt build up also clogs the valve.
------------- Daydream Believer- Hanse 311- No GBR9917T- Bradwell Essex |
Posted By: Tranquillity
Date Posted: 02 April 2025 at 21:46
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Just need to be very very careful if placing a bottle under the pipe the water does not syphon back as Samuel noted, this can be catastrophic. On earlier post it was mentioned that after cleaning with fresh water it leaked more ! I would check the leak is not from the rubber seal on the valve itself as seen this before, if so some silicone gel on rubber seal and joint normally resolves. To check I find easiest way is to dab cap joint with a blue paper roll when motoring to see if seeping. Hope this helps. |
Posted By: Al 348
Date Posted: 03 April 2025 at 14:46
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Thank you, Tranquility I tried that and still leaking. Ordered part Vetus #AV006 from Defender Marine for $14 and should arrive in the next few days and I will keep you posted. Al ------------- Peace through Sailing |
Posted By: Al 348
Date Posted: 17 April 2025 at 20:30
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Dear Friends, I ordered a new Vetus valve air vent, part number AV006 from Defender Marine for $14 https://defender.com/en_us/vetus-valve-air-vent-av006" rel="nofollow - https://defender.com/en_us/vetus-valve-air-vent-av006 The valve looked exactly like the one that was defective. I couldn't see any difference. I replaced it and was very happy to see that the leak stopped. One word of caution; the valve does not come with a new "O" ring. So be careful not to discard the old one. Many thanks to all of you that helped solve this issue. Al ------------- Peace through Sailing |
Posted By: Tranquillity
Date Posted: 17 April 2025 at 21:08
| Great stuff, pleased it worked ! |