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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