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L124C 07-01-2009 03:18 PM

Leaking water pump.
 
1 Attachment(s)
The water pump on my raw water cooled Yanmar 2GM20 Water is leaking. It drips for about an hour after I shut the motor down (I assume until it drains the water in the line). This is the best picture I could get of the bottom of the pump. It seems like the water is coming from the hole in the picture. Any ideas what might be causing it before I tear it apart?

pfatyol 07-01-2009 03:37 PM

The shaft seal is bad, and needs to be replaced. I had it happen to mine a couple of years ago, replaced both bearings and the seal, very easy to do. I have 2GMF. Mine was leaking when the motor was running but it was the exact same spot.

Good luck,

Pat

SEMIJim 07-01-2009 04:11 PM

It's a weep hole. There are two seals in that pump: An outer one to keep water out of the engine and an inner one to keep oil in the engine. That weep hole is between the two. You need new seals. Btw: Don Moyer (Moyer Marine) recommends you put a bit of sealant around the seat of the "outside" seal before installing it, so any minor dings or imperfections in the seal's seat doesn't leave you with water still dribbling out (as happened to me).

And note carefully that the seals go in a certain way: With the stamped lettering on them facing one another.

Jim

JohnRPollard 07-01-2009 04:16 PM

Quote:

Originally Posted by pfatyol (Post 501987)
The shaft seal is bad, and needs to be replaced. I had it happen to mine a couple of years ago, replaced both bearings and the seal, very easy to do. I have 2GMF. Mine was leaking when the motor was running but it was the exact same spot.

Good luck,

Pat

I agree. I'll just add that the hole at the bottom is a weep hole, through which any water leaking from a bad seal will pass.

Another thing: One winter, I forgot to loosen the water pump belt when I winterized our previous 2GM20F. This caused the shaft to sit with uneven tension for the entire winter (4+ months). In the spring, the shaft seal was distorted and it leaked a bit. I was going to replace it, but after using the engine a few hours (probably 10+), the seal seemed to get back in proper shape and it stopped dripping and never dripped again.

So if your boat has sat for quite a while with tension on the water pump belt, try running the engine a bit and see if the seal will reseat itself. If not, it's probably time for a new one.

Maine Sail 07-01-2009 04:40 PM

Time for a re-build
 
Time for a re-build. While not specific to your pump they are all fairly similar in design. This may help:

Re-building A Raw Water Pump (LINK)
http://www.pbase.com/mainecruising/image/110326637.jpg

L124C 07-01-2009 06:33 PM

Quote:

Originally Posted by pfatyol (Post 501987)
The shaft seal is bad, and needs to be replaced. I had it happen to mine a couple of years ago, replaced both bearings and the seal, very easy to do. I have 2GMF. Mine was leaking when the motor was running but it was the exact same spot.

Good luck,

Pat

Thanks everybody! I'm sure mine is leaking while it's running also, I just can't hear it. The Yanmar manual doesn't give me much. I assume when I pull it apart it will be fairly self explanatory? Thanks again!

pfatyol 07-02-2009 08:19 AM

it is actually very simple to rebuild, especially since you can pull the pump off in about 10 minutes and bring home to rebuild. I forget how much the seals and bearings were but I used Torresen for the parts. I ended up stripping and painting the pump / pulley while I was at it.

Marine Diesel Engines and Engine Parts from Torresen Marine's Marine Diesel Direct - Universal - Volvo - Westerbeke - Yanmar - MASE

I actually keep a spare pump on board, so I put in the spare, and rebuilt the leaking one for the new spare. (mechanical engineer so I am a little excessive compulsive)

Pat

L124C 07-03-2009 02:06 AM

1 Attachment(s)
I got the parts from the local Yanmar dealer. Strange thing is, the parts diagram (see picture) calls for 2 bearings (#7) and 1 oil seal (#8). No water seal. The motor is a 2GM20(F). I questioned the lady at Yanmar about it and she showed me the diagram (which she had nicely copied for me) and correctly said "your looking at the same thing I am". This makes me wonder, what keeps the water in the pump, and if I don't have a water seal, whats leaking? I could pull it apart, but have a race coming up and don't want to unable to get a part. Ideas?

Maine Sail 07-03-2009 06:31 AM

Quote:

Originally Posted by L124C (Post 502432)
I got the parts from the local Yanmar dealer. Strange thing is, the parts diagram (see picture) calls for 2 bearings (#7) and 1 oil seal (#8). No water seal. The motor is a 2GM20(F). I questioned the lady at Yanmar about it and she showed me the diagram (which she had nicely copied for me) and correctly said "your looking at the same thing I am". This makes me wonder, what keeps the water in the pump, and if I don't have a water seal, whats leaking? I could pull it apart, but have a race coming up and don't want to unable to get a part. Ideas?

Your pump is belt driven not engine driven therefore you only need one seal. That seal is for raw salt water or lake water. On some engines the pump bolts directly to the engine block where it is splash lubed by oil and driven directly off the engine so you'd have two seals one for water and one for the oil side.. Yours is driven by a belt thus one seal...

L124C 07-03-2009 12:02 PM

Quote:

Originally Posted by Maine Sail (Post 502436)
Your pump is belt driven not engine driven therefore you only need one seal. That seal is for raw salt water or lake water. On some engines the pump bolts directly to the engine block where it is splash lubed by oil and driven directly off the engine so you'd have two seals one for water and one for the oil side.. Yours is driven by a belt thus one seal...

So...should it be dripping water?


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