yanmar 2GM low cooling water volume?? - SailNet Community
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post #1 of 4 Old 05-30-2007 Thread Starter
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yanmar 2GM low cooling water volume??

Started my new to me 25 year old 2GM (raw-water cooled) for the 1st time, and am concerned ablout the small amount of water coming out of the engine cooling system. With the intake hose in a bucket, there is barely a noticeable difference in the bucket water level, after running the engine for a minute. When I disconnect the hose to the exhaust elbow, water is coming out, but slowly. I disconnected the hose from the water pump, and seemed to have about the same amount - didn't want to run it long like that. Took the impeller out - looks fine. Belt / water pump are turning. As it is my 1st diesel, how much water should it use form a bucket in a minute or so??? It goes in the water soon, and I won't be able to see the exhaust, as it exits the boat, from a thru -hull, underneath the boat - not out the transom.

Forgot to mention - one of the 6 impeller cover screws broke / disinegrated when I put the cover back on, with a new paper gasket. Could that allow air in - reducing the pumps power?
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post #2 of 4 Old 05-30-2007
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For what it is worth: I have a 3GMD (25 years old) raw water cooled engine on my boat. I resently checked it out before putting it back into the water. The boatyard management loaned me a 5 gal. bucket that had been adapted with a hose and valve such that I could supply water to the input of the raw water pump.. I questioned as to how long I could run the eng. with only 5gal of water. To my surprise it was several min.

As far as air leaking in the cover plate, I would think you would see water leaking out instead of air getting in.. Still, it is a must to repair or replace the water pump... Yes, more time and / or more money, but a lot less than replacing the eng.
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post #3 of 4 Old 05-30-2007
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It is very easy to get the water pump off if it is like my 2AGM. Just two bolts and I would definately get it fixed. Also I would seriously look at moving your exhaust to the transom so that you can always see if you have cooling water flow. I always check and have not seen a boat set up like yours.
I guess the advantage of your set up is with it exhausting under water you probably do not get black exhaust marks on your transom.

As for the amount of water when mine is running it pulses out a steady stream which would likly fill a normal pail in maybe 3-5 minutes, not really sure but just check someone elses boat exhaust to get an idea of how much should be coming out.

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post #4 of 4 Old 05-31-2007 Thread Starter
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thanks for the replies. The boat went in the water today, and it is working fine now. For some reason, or maybe coincidence, water would only bubble slowly out of the engine, when feeding from a pale. Once I tested it in the water, there was a 3-4 inch column of water exiting the engine, when I pulled the hose off to check.

And, although my thru-hull is underneath the boat, it is just above the waterline, so I can hear the water exiting.
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