Water Pump Yanmar 2GM20F

puff6022 · #1 (**permalink**) 02-13-2008

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.

PBzeer · #2 (**permalink**) 02-13-2008

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.

trantor12020 · #3 (**permalink**) 02-13-2008

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

puff6022 · #4 (**permalink**) 02-13-2008

Island Packet says there is no way the thruhull comes out of the water on either tack

PBzeer · #5 (**permalink**) 02-13-2008

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

RickBowman · #6 (**permalink**) 02-13-2008

Your pump is self priming. What's the problem?

JohnRPollard · #7 (**permalink**) 02-13-2008

Some discussion of problematic prime here:

http://www.sailnet.com/forums/showthread.php?t=39766

EDIT: Another thread:

http://www.sailnet.com/forums/showthread.php?t=40056

blt2ski · #8 (**permalink**) 02-13-2008

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

badsanta · #9 (**permalink**) 02-22-2008

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

trantor12020 · #10 (**permalink**) 02-22-2008

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.