Water Pump

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Posted by John ( on May 06, 2004 at 21:48:10:

In Reply to: water pump posted by jim on 21:09:48 05/06/04:

Typically the water will come out of a boat exhaust in intermittent spurts at idle. It is not a high flow like you would get from a hose. The pump flow rate is also dependent on speed so there is much more flow at high engine speeds then at idle. As for loosing prime I would not expect this to be a problem, even from a bucket. It is a positive displacement pump which should be capable of pulling a fairly high suction lift. Of course the pump is normally below the water level when the boat is in the water, so elevating the bucket could be having an effect. The bottom line is that if the engine is not overheating, it is getting enough water. If you are having an overheating problem you should check the pump to make sure nothing is wrong. I assume you have one of the later style Oberdorfer pumps with a rubber impeller. Even the earlier engines that originally had an iron gear pump have usually been converted to an Oberdorfer. If not you should do it. With the Oberdorfer I can think of two things that would cause low flow. An incorrect impeller could be installed or one of the rubber blades could be broken (assuming the impeller was replaced with the rebuild-a worn out impeller could be the reason also). You just have to remove the 4 screws on the end cover and pull out the impeller to check it. Be sure you have another gasket for reassembly (you should have a spare impeller and gasket on board anyway). Note there is also a modification available to increase the flow of the Oberdorfer pump. Check the Moyer Marine website.

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