Bob — with the Sendure after-market cooling system, you end up with two pumps: the stock Yanmar pump on the engine which on my boat currently pumps coolant; and the add-on pump that on my boat currently pumps lake water. I would basically be bypassing the Sendure system with the add-on pump and heat exchanger, and converting back to the stock raw-water cooled system. In my case, that would be cold Lake Superior fresh water, so I’m not too worried about engine temp.
This is how many C&C’s were delivered from the factory; with no coolant system, just raw seawater. — Fred Fred Street -- Minneapolis S/V Oceanis (1979 C&C Landfall 38) -- Bayfield, WI > On Aug 9, 2019, at 2:39 PM, Robert Boyer via CnC-List <cnc-list@cnc-list.com> > wrote: > > Fred: > > What is going to make the seawater circulate through the engine? Are you > going to the raw water pump to circulate seawater through the engine’s > cavity? I would think that the volume of seawater circulated would need to > be greater than the antifreeze/water mixture normally in the closed cooling > system since it is less efficient in heat exchange but there may be enough > seawater that would be pumped by the raw water pump. You might find that the > temperarture will run a little higher than normal. > > >> On Aug 9, 2019, at 2:04 PM, Frederick G Street via CnC-List >> <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: >> >> Hello, all — I’ve got a 1979 LF38 with the original Yanmar 3QM diesel, >> fitted with a Sendure fresh-water exchanger kit (also original). >> >> Over the last season or so, I’ve been noticing a slow but accelerating drop >> in the coolant level. In the last month, it has sped up quite a lot. It’s >> not getting into the oil, and the head gasket is relatively new. With the >> recent acceleration, there’s also a lot of white smoke (steam) in the >> exhaust as well. >> >> I’m thinking the heat exchanger may have developed a leak (or leaks) between >> the fresh and raw water sides. I’m going to pull it this weekend and test >> it to see if that’s the case. I am also going to replace ALL coolant hoses >> (fresh and raw, including the loops to the water heater and the v-drive). I >> ordered 50 feet of 1/2” and 3/4” Gates green-stripe (off Amazon) to keep >> costs lower per foot and make sure I have enough; this may also allow me to >> perform a temporary fix in case the exchanger is toast, by completely >> bypassing the Sendure system and effectively making the engine raw-water >> cooled until I can decide what to do with the exchanger. This would also >> allow me to go on an extended weekend cruise next weekend without worry. >> BTW, so that I don’t have to try to size new belts for the engine, I’ll >> leave the add-on coolant pump in place, but remove the impeller and just let >> it freewheel for the temporary fix (with no hoses connected). It’s fairly >> new, I replaced it a few years ago. >> >> Anyone see any downsides to this plan; or any other places I can look for >> the missing coolant? 🙂 >> >> — Fred >> >> >> >> Fred Street -- Minneapolis >> S/V Oceanis (1979 C&C Landfall 38) -- Bayfield, WI
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