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Yanmar 2GM water cooling
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Yanmar 2GM water cooling
Marc Auslander wrote in
: (Trai) writes: The pump on this boat will work any time, for as long as I want it to run, its only after sailing (motor off) and the boat being heeled over for a long period that it gives trouble. After about a hour of sitting at the slip its all ready to go again. I am stumped  Sounds like the pump is loosing its prime. The pump is not good at pumping air. You might try priming it manually the next time it happens to see if that fixes it. On my boat, I would do that by pulling the intake hose off the thru-hull, poring water down it, then reattaching it. I wanna look at his anti-siphon break in the exhaust hose and the position of the hose's loop above the waterline when he's heeled over hard. When he's heeled over, so is the loop. I agree the pump is coming unprimed, but should prime again as soon as the boat goes upright. But, alas, if there is water standing in the exhaust hose pushing back into the engine, the bubble of air has no place to go out of the water pump impeller when it starts turning. So, the engine is "vaporlocked" with that bubble of air stuck in the pump. Normally, when the impeller starts to turn, the water pressure from the seacock simply pushes the bubble out of the pump as the impeller turns because the impeller is under the waterline so the bubble moves on. If there is water in the exhaust pushing backwards on the impeller, the air bubble in the pump is trapped and cannot let the impeller prime. This will happen if the loop every gets so flat it allows water to go over the loop to the engine side. Stand the loop back up and there's now a water column trapped on the engine side of the loop. If there's no leaks, the column is blocked by the stopped impeller acting as a valve. (water doesn't flow by a good impeller in either direction unless it turns). OF course, he COULD have a bigger problem if this is happening and it shoves water in those exhaust ports into the cylinders. Been there, recently, done that.....not pretty.... Larry |
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