I have read a few posts regarding leaving the raw water closed while cranking the engine to start so the water doesnt load up in the exhaust. My engine has always started right up. I have never done this, so what is the opinion here? Open? Or closed until it starts then open it? I just hate to have the possibility of running the impeller dry.
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open it, then start the engine...
it only takes about 15 seconds with no water to fry an impeller. Engine problems and maintenance procedures notwithstanding, as long as your engine is easy to start, I would not risk it. The smell of a burning impeller is hard to forget.
it only takes about 15 seconds with no water to fry an impeller. Engine problems and maintenance procedures notwithstanding, as long as your engine is easy to start, I would not risk it. The smell of a burning impeller is hard to forget.
Water first.
I agree with Steve, run with water. If you had to crank several times you might consider having someone at the thru-hull to turn it on at first sign of firing. But as long as it starts within five or ten revs always open it first.
I agree with Steve, run with water. If you had to crank several times you might consider having someone at the thru-hull to turn it on at first sign of firing. But as long as it starts within five or ten revs always open it first.
Not sure that this is true.
I was told that it is okay to try to start the engine with the raw water intake in the off position. If you are trying to start an engine that has a problem, you are pumping raw water thru the engine and into the muffler. The problem that can occur is the fact that water (in theory) can backup into the exhaust side of the engine if there is no exhaust to push the water out. This is something we may want to get an answer from someone that has taken the class or a Yanmar mechanic. I have started my engine withoout the raw water intake turned on. I ran it for several mintues after it started before I realized what was going on. It did not do any damage to the impeller. I normally do not turn off the raw water intake. I know, I know you really should.
I was told that it is okay to try to start the engine with the raw water intake in the off position. If you are trying to start an engine that has a problem, you are pumping raw water thru the engine and into the muffler. The problem that can occur is the fact that water (in theory) can backup into the exhaust side of the engine if there is no exhaust to push the water out. This is something we may want to get an answer from someone that has taken the class or a Yanmar mechanic. I have started my engine withoout the raw water intake turned on. I ran it for several mintues after it started before I realized what was going on. It did not do any damage to the impeller. I normally do not turn off the raw water intake. I know, I know you really should.
Engine start
First, I close ALL thru-hulls when I leave the vessel for more than a day. Obviously the thru hull should be open when starting the engine. Do you think all the commercial and pleasure power boats close when starting? If the engine doesn't start within a reasonable time close the intake. I found this out the hard way many years ago when I hydrolocked an Atomic 4 that would not start.
First, I close ALL thru-hulls when I leave the vessel for more than a day. Obviously the thru hull should be open when starting the engine. Do you think all the commercial and pleasure power boats close when starting? If the engine doesn't start within a reasonable time close the intake. I found this out the hard way many years ago when I hydrolocked an Atomic 4 that would not start.
The Impeller Is Not Running Dry
Unless it is the first start of the season, there is water in the impeller housing which will lubricate the impeller for a little while. I don't think you would want to run it more than a minute, but once the diesel starts it doesn't require breaking a leg to get to the intake shutoff and turning it on. I take the impeller out for the winter so none of the blades are bent over for several months at a time. When I reinstall it, I put a light coat of Vasaline on it to lubricate it until the water starts to flow. That also will cause it to start pumping more quickly as well. With all of that said, I normally start with the valve open. The only reason I would close it would be if the diesel doesn't start immediately. In that case I close the valve and then go back to cranking the diesel, bleeding the lines, etc., until I get it going. Then I reopen the thru hull.
Unless it is the first start of the season, there is water in the impeller housing which will lubricate the impeller for a little while. I don't think you would want to run it more than a minute, but once the diesel starts it doesn't require breaking a leg to get to the intake shutoff and turning it on. I take the impeller out for the winter so none of the blades are bent over for several months at a time. When I reinstall it, I put a light coat of Vasaline on it to lubricate it until the water starts to flow. That also will cause it to start pumping more quickly as well. With all of that said, I normally start with the valve open. The only reason I would close it would be if the diesel doesn't start immediately. In that case I close the valve and then go back to cranking the diesel, bleeding the lines, etc., until I get it going. Then I reopen the thru hull.
Well,
at a Yanmar Engine course, we were told to "pre-lube" the engine (if it has not been run within the past 48 hours) by closing the raw water intake thru-hull; cranking the engine while holding the "kill" switch, until the oil pressure alarm stops; then opening the thru-hull and starting the engine. This technique coats the cylinder walls with oil prior to starting the engine and prevents water from entering the engine thru the exaust manifold. It appears to do little, if any, harm to the impellor; and prolongs engine life by "pre-lubracating" the engine prior to ignition.
at a Yanmar Engine course, we were told to "pre-lube" the engine (if it has not been run within the past 48 hours) by closing the raw water intake thru-hull; cranking the engine while holding the "kill" switch, until the oil pressure alarm stops; then opening the thru-hull and starting the engine. This technique coats the cylinder walls with oil prior to starting the engine and prevents water from entering the engine thru the exaust manifold. It appears to do little, if any, harm to the impellor; and prolongs engine life by "pre-lubracating" the engine prior to ignition.
Bologna!!
The lubrication for the cylinder walls comes from splash oil thrown up by the rotating crankshaft. This happens while the engine is being cranked by the starter. If you believe this junk about dry starts, ask yourself "Why don't ALL internal combustion engines have to be cranked before starting?" As for the closed thru-hull, the vaccum created in the supply hose is putting an excessive load on the impeller which will lead to premature failure.
The lubrication for the cylinder walls comes from splash oil thrown up by the rotating crankshaft. This happens while the engine is being cranked by the starter. If you believe this junk about dry starts, ask yourself "Why don't ALL internal combustion engines have to be cranked before starting?" As for the closed thru-hull, the vaccum created in the supply hose is putting an excessive load on the impeller which will lead to premature failure.
Well. Buck
My manual says that if the engine has not been run for an extended time-(several weeks)-that the engine should be turned over for a maximum of ten seconds to circulate the lubricant. Engine stop on. Says nothing about shutting the intake. I'm paraphrasing since I don't have the manual here, but I believe that's accurate. Rick D.
My manual says that if the engine has not been run for an extended time-(several weeks)-that the engine should be turned over for a maximum of ten seconds to circulate the lubricant. Engine stop on. Says nothing about shutting the intake. I'm paraphrasing since I don't have the manual here, but I believe that's accurate. Rick D.
Well guys,
Only telling you what we were told by a Yanmar certified mechanic....... re. time period... after about 48 hours (much less several weeks), virtually all oil has drained off of cylinder walls...and engine should (according to Yanmar) be 'pre-lubed' prior to actual starting... re. I agree that, (about)ten seconds of turning engine over without starting establishes oil pressure (low oil pressure alarm warning buzzer stops) re. closing raw water intake while preforming this pre-lube.... Yanmar's mechanic agreed that chances of water being drawn into engine thru exause manifold are remote, but this IS what Yanmar recommends.... ck for yourself.... Don't shoot me, I'm just relaying the message
Only telling you what we were told by a Yanmar certified mechanic....... re. time period... after about 48 hours (much less several weeks), virtually all oil has drained off of cylinder walls...and engine should (according to Yanmar) be 'pre-lubed' prior to actual starting... re. I agree that, (about)ten seconds of turning engine over without starting establishes oil pressure (low oil pressure alarm warning buzzer stops) re. closing raw water intake while preforming this pre-lube.... Yanmar's mechanic agreed that chances of water being drawn into engine thru exause manifold are remote, but this IS what Yanmar recommends.... ck for yourself.... Don't shoot me, I'm just relaying the message
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