Yanmar 2GM20 + Vetus LP40 Waterlock

[shacks]

Hi, I have a First 305 that has a Yanmar 2GM20 engine (RAW water fed) and a Vetus LP45 Waterlock fitted. Looking at the manual for the engine it shows that the water pipe from the Thermostat goes straight to the Exhaust elbow but on my boat this pipe has a "T" piece fitted, so as well as going to the exhaust elbow it also goes to a fitting on the back end of the Vetus Waterlock above the Exhaust outlet. The fitting here is not shown on any picture I have seen of the Vetus Waterlock. It has now become detached and is leaking water. The pipe work for the "T" piece etc has all been fitted in place and does not look like an "after thought". What I would like to know is "can I do away with this pipe?" as at some time in the future I would like to fit a calorifier and I believe that the pipe between the Thermostat and the exhaust elbow is the pipe that I would fit it to. Thanks Steve

 

[Tranona]

That is probably a syphon break to stop water getting back into the engine. Normally it would use an anti syphon valve. See the Vetus catalogue on www.vetus.co.uk page 168. It will not show in the Yanmar handbook because their solution when an engine is fitted at or below the waterline is a high rise manifold. Not the best bit of kit and a separate valve is probably a better solution.

Hope this helps

 

[shacks]

Thanks Tranona, I think you are correct and it is a syphon break.

 

[vyv_cox]

I don't know enough about the raw water cooled Yanmar to give definite advice, but on many engines a calorifier will not work if heated in the way you suggest. If the water leaving the engine is a mixture of heated and bypass water its temperature will be too low to heat the calorifier to an acceptable level. The best way is to circulate water from the top of the engine, to the calorifier, to an electric pump, back to a cool part of the engine. Most production engines have blank plugs or some sort of fitting that can take the necessary hoses. See my website for more information.

 

[prv]

Can you get calorifiers that will take seawater? I too have a raw-water engine, and I'd heard that it wasn't suitable for a calorifier as it would corrode. (In any case I almost certainly have no space for one, so I didn't look into if further)

Pete

 

[vyv_cox]

Certainly, any that have a copper coil, which I suspect is most of them, will be perfectly OK. Mine was about 20 years old when I replaced it because I could not get the large blank off the top to add an immersion heater. I cut the old one up to assess its condition. The coil was still in good condition.

Have a look at the current thread by Snooks - Bukh raw water engine plus calorifier.