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Discussion Starter #1
I have an 86 Island Packet 27 with a Yanmar 2GM20F. I keep losing prime to the raw water pump. I have moved my raw water strainer down to waterline, replaced all hoses, had the raw water pump rebuilt, and I continue to lose prime. My question is, can the raw water pump get too old to effectively be rebuilt? Should I just breakdown and buy a new ($400.00) water pump? It seems to happen when I am heeled over while sailing, not when I am upright and motoring. Wits End.
 

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Wandering Aimlessly
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Does it happen on either tack, or just one? It sounds like the intake is coming out of the water, and that's why you're losing prime.
 

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Rebuilt means replacing the impeller and the cam inside the pump ?
 

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Wandering Aimlessly
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If you don't lose your prime when sailing or motoring flat, and you do when heeled, something is stopping the inflow of water.
 

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I got a leak in my 85 2gm20f about Jan 1. the gasket went haywire. I did not have a gasket so found and made do with some gasket material. was too big, so no fluid would pump thru. Removed the gasket all together, and used some Tstat silicone tween the back and the main unit, and it works fine now. Unfortuneatly, had a small over heat issue last sunday in some 30-40 knot winds!

Otherwise, I am not sure what to say re losing the prime. As i was checking initially to see why no water would go thru. One of my tests, was to open the valve with the pump not connected, and water would flow up thru my hose. Next step was to see if any got to the inlet in the radiator part. Nothing. So that left the pump for me anyway, not working at all.

Not sure why, other than maybe something is floating around in the inlet that you can not see, ie a rock, small sea shell type creature etc

marty
 

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If your fresh water pump vains were damaged before rebuild you may have rubber pieces blocking the heat exchanger tubes.
How do you know you are lousing prime? If you are saying no water comes out the exaust when the motor is running, Then either the thru hull intake valve is closed, or the fresh water pump is bad or the power belt is loose or broke or the heat exchanger is clogged. Or your exaust elbow is cloged.
I would look at the heatexchanger and the exaust elbow. Unless you have other info
 

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Could your impeller be fitted in wrong direction? I know the 2GM20F water pump (Johnson 810) doesn't follow the direction indicated on the pump cover plate. Mine is reverse.
 

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Similar problem - no Water at all - is there really a way to prime?

Hi all,

I just got my boat back in the water after a broken prop and bent shaft (long story but it has to do with a submerged deadhead and on the way OUT on a 4 day weekend. grrr...)

When I started the motor up I had no water move through the system at all. Last year I replaced my mixing elbow which was the culprit but I can't imagine it built up soot and blocked again so quickly.

The boat has been in the yard for work (and waiting for parts) for about 45 days and I could not find any blockage when I checked the sea cock, strainer and impeller this afternoon and all seemed to have water. Any ideas what may be the problem? When the yard replaced the prop shaft, does that have any effect on the cooling system? Is there an easy way to check the heat exchanger? Could it be something simple I just didn't see? Yes, I opened the throughull :)

I noticed a couple posts about the pump "priming" how would I bleed air out of the system to prime it?

thanks in advance!
Matt
 

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Discussion Starter #13
I found the problem, On a strong starboard tack (my thru hull is on the starboard side) the thru hull comes out of the water allowing the hole system to drain and loose prime. I am going to install a check valve between the thru hull seacock and my raw water strainer. I've had the boat since 2001 and never had the problem until now. I just replaced my sails, and therefore heel more. Thanks for all the input.
Puff
 
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