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Sea Alles 08-18-2013 11:03 PM

Yanmar water backflow
 
This has happened twice within the week. Upon shut down of our 3 cylinder Yanmar, it syphons water back into the manifold, preventing the start of the engine. The first time was a four hour search. Today the diagnosis was much quicker. Both times the boat had six adults aboard and the wet exhaust outlet would have been under water. I don't want to tell all our guests to move to the bow so I can shut down!! I am getting good at sailing in the harbour.
The exhaust line appears to have an upward loop--like a sink drain, but that doesn't stop the backflow. Can a check valve/anti syphon be installed? I recall seeing a flap on the hull of an exhaust outlet-I assume to prevent this issue.

Any help appreciated

Thanks

Kevin Alles
Bayfield 32 Sea Alles

PaulinVictoria 08-18-2013 11:32 PM

Re: Yanmar water backflow
 
How high is the loop? Might be that it's high enough normally, but not when the extra load is onboard.

aa3jy 08-19-2013 07:41 AM

Re: Yanmar water backflow
 
Check your anti-syphone valve in the loop. There should be one installed

Sea Alles 08-19-2013 08:38 AM

Re: Yanmar water backflow
 
Thanks for the info. I'll investigate these suggestions.
Kevin

Maxion 08-19-2013 09:21 AM

Re: Yanmar water backflow
 
On most every boat I've been to the exhaust outflow is above the waterline. IMO if it isn't when you've got 6 people onboard you should re-locate it higher up.

JimsCAL 08-19-2013 06:35 PM

Re: Yanmar water backflow
 
Do you have the "low rise" or "high rise" mixing elbow? If the former, a change to the later would help. The high rise is a casting that makes a 180 degree turn, with the exhaust entering up and the exiting down.


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