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#1
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Yanmar 2GM water cooling
Hi all
Some advice on where to look next would be greatly appreciated. I have a Yanmar 2GM diesel engine that stops pumping water through the cooling system after I have been out sailing for the day. To get it started pumping again; I need to let the boat sit flat in the water for about an hour. I have changed the impeller, but still have the problem. The only time this seems to happen is when I have the boat heeled over for a few hours. Any ideas? Thanks Trai |
#2
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Yanmar 2GM water cooling
Trai wrote: Some advice on where to look next would be greatly appreciated. I have a Yanmar 2GM diesel engine that stops pumping water through the cooling system after I have been out sailing for the day. To get it started pumping again; I need to let the boat sit flat in the water for about an hour. I have changed the impeller, but still have the problem. The only time this seems to happen is when I have the boat heeled over for a few hours. Trai, use Google to search rec.boats.cruising via the Groups section using the keywords: yanmar overheating jeffrey. Read the thread (there are several, but you're about at the point I was, so you can probably skip everything I went through prior). Apparently this is not a rare issue. Many insightful and helpful comments and suggestions were posted by the many knowledgable people here. |
#3
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Yanmar 2GM water cooling
Trai wrote:
Some advice on where to look next would be greatly appreciated. I have a Yanmar 2GM diesel engine that stops pumping water through the cooling system after I have been out sailing for the day. To get it started pumping again; I need to let the boat sit flat in the water for about an hour. I have changed the impeller, but still have the problem. The only time this seems to happen is when I have the boat heeled over for a few hours. Btw, just out of curiosity, what is the boat and where is it located? The boat discussed in the thread I referenced is a 1989 S2 (built on and for the Great Lakes, afaik) that is now in San Francisco. |
#4
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Yanmar 2GM water cooling
Btw, just out of curiosity, what is the boat and where is it located? The
boat discussed in the thread I referenced is a 1989 S2 (built on and for the Great Lakes, afaik) that is now in San Francisco. Hi there Thanks for the reply - the boat in question is a Sunstar 28 and is located in Vancouver BC. I took a look at that thread and there is a lot of information there. There are some differences in the problem however. 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 |
#6
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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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