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-   -   raw water pump leak on Yanmar 3Gm30F (http://www.sailnet.com/forums/gear-maintenance/43867-raw-water-pump-leak-yanmar-3gm30f.html)

gsyversen 06-05-2008 12:43 AM

raw water pump leak on Yanmar 3Gm30F
 
hello all, I'm new to this forum and seen many posts about my engine so I'm hoping someone here can help me... a few weeks ago I noticed water in the engine bilge and found the source to be a drip from the raw water pump. there is some corrosion on the screw there so its not new but seem to be getting bigger....

I got a quote to get a new raw water pump for $400 and change and find that steep. Anyone have an opinion if this is something that shold be rebuilt, left along or just flat out replaced. I like the last and keep the old as spare as that seems the safest and I'm close to doing it but I tohght a check here would be woth it...

any comments appreciated !

Gaute

artbyjody 06-05-2008 02:17 AM

Quote:

Originally Posted by gsyversen (Post 324623)
hello all, I'm new to this forum and seen many posts about my engine so I'm hoping someone here can help me... a few weeks ago I noticed water in the engine bilge and found the source to be a drip from the raw water pump. there is some corrosion on the screw there so its not new but seem to be getting bigger....

I got a quote to get a new raw water pump for $400 and change and find that steep. Anyone have an opinion if this is something that shold be rebuilt, left along or just flat out replaced. I like the last and keep the old as spare as that seems the safest and I'm close to doing it but I tohght a check here would be woth it...

any comments appreciated !

Gaute

Don't quote me on this - but I think all you need to do is replace the impeller on it and secure it with a new gasket...It5s probably a simple rebuild and the basic kit runs about 75 - 150 bucks, way cheaper than a new one...

gsyversen 06-05-2008 09:54 AM

Like the sound of that...
 
but how can you really tell, this is an important part and its 10 years old... what is the life expectancy for this thing and do I invest in a kit for then to find out the bearings are gone... or perhaps I shold open it and determine then if it can be fixed ?

NOLAsailing 06-05-2008 09:58 AM

There's not much to a water pump - it's belt driven and it spins a shaft connected to the impeller inside a housing. It's mechanically very simple. You should replace the impeller and the gasket at least once a year. Do this before you worry about replacing the whole pump. Be sure you get the old gasket completely off. If it's old, it will likely be well adhered to the water pump cover.

http://www.rambunctiousracing.com/im...old_gasket.jpg

sailingdog 06-05-2008 10:07 AM

Whatever you do, try not to scratch the impeller cover. Scratches there will impair the impeller efficiency and may damage the impeller itself.

JimsCAL 06-05-2008 10:21 AM

The leak could be the shaft seal. This is replaceable if you can get the right part. Had this go twice on the raw water pump for my Universal 5411. The price for a new pump for my engine was over $400 last time I checked, so the price you got for your Yanmar pump is in the ballpark (unfortunately).

JohnRPollard 06-05-2008 10:53 AM

Gaute,

That is not a very old pump, at 10 years of age. We have the same engine, and ours is the original pump at 18 years. Engine hours are more of the issue.

I can't say for sure where it's leaking from. Could be the gasket has a bad seal. The shaft seal is the other likely culprit.

On a previous boat with a 2GM20F (exact same raw water pump), I had a drip leak from the shaft seal. This leak developped at the beginning of the season, after I had de-winterized the boat. It was my first year of boat ownership, and when I had winterized the boat at the end of the previous season, I had neglected to loosen the raw water pump belt. This caused the shaft to have uneven pressure on it for several months, resulting in the seal becoming slightly off-round/misshapen.

When I detected the leak, I had the same thought as you: Buy a new pump, and/or re-build the old one as a spare (re-build kits ARE available). But an experienced mechanic gave me some good advice: He said to use the engine as much as possible, and see how much the pump was dripping after a month or so. He was right, it turned out that by operating the pump, the seal re-seated/shaped itself and the leak dissapeared in a few weeks.

You might try this too, especially if the boat had been sitting for a while with a tight belt. Just a suggestion, Good luck!

NOLAsailing 06-05-2008 11:24 AM

Quote:

Originally Posted by JohnRPollard (Post 324792)
When I detected the leak, I had the same thought as you: Buy a new pump, and/or re-build the old one as a spare (re-build kits ARE available). But an experienced mechanic gave me some good advice: He said to use the engine as much as possible, and see how much the pump was dripping after a month or so. He was right, it turned out that by operating the pump, the seal re-seated/shaped itself and the leak dissapeared in a few weeks.

That's interesting. Good to know.

beej67 06-05-2008 03:57 PM

Gaute,

Definitely take your pump off, take the back plate off, and have a look around in there, if you never have before. People usually recommend replacing the impeller yearly, although I can get away with waiting 2 years depending. Always always always have a spare impeller onboard for your raw water pump, it's an item that breaks often. Replacing it really isn't that hard, you just remove the two bolts that hold your raw water pump on, pull the pump off, detach the two hose clamps, and carry the pump over to a table and unscrew the screws. Take a look inside, see if any of the rubber impeller wings are cracked - if they are, you need a new impeller. Even if they're not, go ahead and order one or two spares, you'll need them eventually. Make sure the belt is tight when you put it back on.

I have to stand on my head to get down in there to remove mine, because of where it's located. Grr. Other than that, it's no big deal.

sailingdog 06-05-2008 03:59 PM

When you replace the impeller in your water pump, which should be done as a normal maintenance item, if the old impeller is in relatively good shape, keep it for use as a backup or spare. :)


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