# raw water pump leak on Yanmar 3Gm30F



## TSOJOURNER (Dec 16, 1999)

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


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## artbyjody (Jan 4, 2008)

gsyversen said:


> 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...
> 
> ...


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...


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## TSOJOURNER (Dec 16, 1999)

*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 ?


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## NOLAsailing (Sep 10, 2006)

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.


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## sailingdog (Mar 19, 2006)

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


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## JimsCAL (May 23, 2007)

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).


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## JohnRPollard (Mar 26, 2007)

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!


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## NOLAsailing (Sep 10, 2006)

JohnRPollard said:


> 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.


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## beej67 (Apr 2, 2008)

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.


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## sailingdog (Mar 19, 2006)

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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## TSOJOURNER (Dec 16, 1999)

*great advice everyone !*

I'll try some of these ideas before I invest too much $$... I also got someone saying the old pumps are still avaliable at far more reasonable price but might have a different impeller. I'm taking it off and replacing the impeller first, last year a mechanic did the replacement so it will be nice to get to know this myself. thanks again everyone and I'll post updates as I go.

I'm also replacing fuel filters on it but that might be another post entirely 

Gaute


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## Rockter (Sep 11, 2006)

It's not the impeller that's causing the leak.
It will be the shaft seal that's doing it. The seal is not expensive, but check that the shaft is not a-wobble. If it is, it is likely to fail the new seal promptly. I had to buy a new pump then, for my olde Volvo.
Look carefully as to from where it is dripping. 
If you do need a new pump, there are likely to be after-market replacements... mine was from Jabsco, and it cost about £75 ($150) back in 1994.


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## TSOJOURNER (Dec 16, 1999)

*removed pump and big oops*

ok, I removed the pump today, pretty easy... opened it to inspect the impeller and found that two wings are missing. I'm was terrified where they could have gone so I started looking thru the hose going to the engine. One fell out when I started bending it but one is completely missing....

Has anyone experienced anything like this and should I get the expert to take the whole thing apart looking for the second blade ?

I'm also wanting a new pump for it, the one I have has some rust on the bolts and the shaft so I'm going for a new and keeping this as a spare. I found the one I need and there are a variety of models but a replacement for the exact same thing if $160... not bad..

I'd really appreciate some feedback on the blade, its making me really nervous.


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## chef2sail (Nov 27, 2007)

Where did you get the replacement from. I have the exact same engine.

Dave


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## adamtroyg (Aug 6, 2007)

i've got the 2gm20f and believe that they are realively the same in this aspect. get the shop manual! it's the bible. i've been having problems with mine cooling systyem and after cleaned the strainer and changed my impeller i took out the heat exchanger. it's at the top of the engine. if you're only looking for an impeller wing just take the front off. only 4 bolts on mine (once i got the fuel filter out of the way ( two bolts)) at that point you will see the 3" across tube with about 70 holes in it for the sea water cooling. don't disturbe the gasket or you'll lose all your anti freeze. your impeller wing couldn't have gotten any farther than that in one piece.


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## adamtroyg (Aug 6, 2007)

sorry for the additional reply, I'd call a guy named Bob that works in the Yanmar distributer for the area. his number is 1-866-526-9717. he's worth talking to . . . (i'll be calling him tomorrow about my 2gm20f flow post )

good luck ,


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## TSOJOURNER (Dec 16, 1999)

*I'll start digging thru the engine*

I thought there might be somewhere it would get stuck. I have the shop manual but the pictures are hard to read, atleast for me, and I'm not that mechanically savvy yet.... I thought the fuel filter was way in the back on left side but I do see where the hose goes into the head exchanger... I'll see how far I get, atleast the mechanic won't have to pull it all apart.

Dave, I got mine from a non Yanmar dealer, they say this is the same pump I have (from Johnson in sweden) and its not the new Yanmar distributors sells today. The price difference is $300 (actually $550 at highest quote I got), I'm still not 100% this part fits but the vendor was positive and willing to repay if it doesnt. I'll send you name and number when I know its a match and it works for my engine. I'm a bit hesitant sending out names of vendors until I know they are the real deal. I'll know wednesday, if I can get my impeller part out 

thanks !
Gaute


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## beej67 (Apr 2, 2008)

gsyversen said:


> ok, I removed the pump today, pretty easy... opened it to inspect the impeller and found that two wings are missing. I'm was terrified where they could have gone so I started looking thru the hose going to the engine. One fell out when I started bending it but one is completely missing....
> 
> Has anyone experienced anything like this and should I get the expert to take the whole thing apart looking for the second blade ?
> 
> ...


It should indeed make you nervous, but it's not the kind of thing you can't do yourself. First thing is to completely remove the hose from the raw water pump to the heat exchanger, and straighten it out and look through it, to see if there is any chance it got stuck sideways in there. That's the most likely thing in my opinion, and is an easy fix - just get yourself a new hose. If not that, then check your exchanger. If you do replace the hose, make sure you ziptie it out in such a way that the belts won't abrade against it.

Adamtroyg gives good advice - if you're just looking to see if you've got a blade stuck in your heat exchanger, you can take the front plate off, should be pretty easy. If you don't see the blade in there, keep looking downstream, which should mean a smaller hose between your exchanger and your mixing elbow.

If the blade part was able to pass through that hose into the elbow, then chances are it passed all the way through the elbow (which has a wider cross section than the hose) and through the muffler and out the boat, so I wouldn't worry past that. You just want to make sure your heat exchanger is clear of debris.

My experience with impeller wings on these pumps is they have a tendency to tear in two locations, one right by the bulb and one down at the base. If you can't find the wing in those two places mentioned above, then it's likely it tore into small enough pieces to pass through your whole system. That or it's floating in your muffler, upstream of the baffle, which probably isn't any harm so don't worry about it. Screwing around with your muffler can be a big PITA, as they tend to break if you push/pull on them too hard while you're trying to hose clamp them. (personal experience, ugh, I hate mufflers)

I realize you may be a little freaked out about this experience, but it's happened to plenty of us, and in the end it's just incentive to check the impeller once a season. And now that you know how to fix it, you can troubleshoot similar problems in the future should they arise, which is an important skill for a sailboater. I can't tell you how many major malfunctions I've fixed while on the hook. It's part of the fun.


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## TSOJOURNER (Dec 16, 1999)

*thanks Beej*

great post Beej and getting a kind word in addition to experienced hel is great. your right, its part of the fun but I was expecting a small little maintenance and it turned into a piece lodged into the engine somewhere, atleast thats what I thought at the time.

Good advice on the hose, since one piece was in the host chances are the other one is too, there is a ziptie or two guiding it so I'll make sure I mark those locations... is this hose of a specific type ? it seemed to have a cover that was somewhat different, like a paint on it.... I'll call the local yanmar guys tomorrow they are great for small parts.

thanks for all help guys I'll post an update as I get the pump wed and hopefully install it same day or thursday.... oh also, how long can I run the engine while debugging the raw water problem ? I'm thinking the impellers probably need water as well as the engine not over heating, just trying to figure how much time I have to test the new setup.

thanks!
Gaute


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## Omatako (Sep 14, 2003)

One impeller blade in the system will not cause you any problems unless you're extremely unlucky. Despite soem doom-prophet posts above it simply isn't big enough to cause a blockage in the cooling system.

The probable worst-case scenario would be if it gets stuck in the thermostat and stops it from closing. Even here it isn't big enough to noticeably restrict flow and it will more likely cause the engine to run cooler rather than hotter.

Don't sweat about not finding it, it's more than likely long gone anyway.

Andre


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## beej67 (Apr 2, 2008)

> Don't sweat about not finding it, it's more than likely long gone anyway.


If it's not in the hose, and not in the heat exchanger, and not in the hose to the mixing elbow, then it's not going to cause you any problems. One of those jammed in a hose could definitely cause problems, though, so it is in your best interests to spend an hour and a half checking those three things for it. If it's not there, shrug and move on with the pump replacement.



gsyversen said:


> great post Beej and getting a kind word in addition to experienced hel is great.


I find kind words go a long way to reinforcing your confidence when working on sailboats. First (and only, thank god) time I broke my muffler, I was troubleshooting my exhaust system in much the same way as we're talking about in this thread. I cursed, screamed, yelled, and made a general ass of myself in my marina, ended up asking an Old Codger down the way for advice. He and his wife were both in their 80s, had given up their sailboat in favor of a Maine lobsterboat, converted for light coastal cruising, since it was flat, slow, and easy to get around in for old folks. He went on to tell me how he'd broken at least 3 mufflers in his day, and not to worry about it so much.



> Good advice on the hose, since one piece was in the host chances are the other one is too, there is a ziptie or two guiding it so I'll make sure I mark those locations... is this hose of a specific type ? it seemed to have a cover that was somewhat different, like a paint on it.... I'll call the local yanmar guys tomorrow they are great for small parts.


If I recall correctly, the "original" hose that connects the raw water pump to the heat exchanger on a Yanmar is pre-bent, to follow the contours of the engine and whatnot, and is painted the same color as the engine. If you can get a replacement from Yanmar that'll work fine, but I just used a length of radiator hose when I replaced mine. It bends out away from the engine kinda funny, so I ziptied it away from the belts so they don't rub. These are the concessions you make when you're doing maintenance an hour drive from the nearest marine parts store, and when your local Yanmar dealer is such a bunch of losers they can't even order you a radiator cap without screwing it up.



> oh also, how long can I run the engine while debugging the raw water problem ? I'm thinking the impellers probably need water as well as the engine not over heating, just trying to figure how much time I have to test the new setup.


Watch your overheat light, your engine's good until it starts to glow, as far as I'm aware. For the impellers, don't sweat running them dry a little bit starting up. It'll usually take your engine ten, maybe twenty seconds to get the raw water all the way through the system, so monitor your exhaust for water. Also, I check my tailpipe every time I start the engine, out of habit, and I highly suggest you pick that habit up as well, it's the first easy check whether your raw water system is working. Once you get a feel for how much water should be coming out of your tailpipe, you can infer when you've got a problem before it gets too bad.

DO NOT FORGET to open your seacock! That's got to be the #1 source of "whoops" error when troubleshooting a raw water pump. I heard one guy say (maybe on here) that he ties his engine key on a string, and hangs it on his thru hull valve whenever he shuts it, to remind him not to start the engine without opening the thru hull.

Another note - this is something I only recently found out about - mixing elbow lifespan is supposedly only 8 or 9 years, and should be replaced as part of general maintenance. In addition, idling Yanmars is supposedly bad for them, because it causes carbon buildup in the exhaust system. I never knew that until recently. I've got a carbon problem in my current mixing elbow, and have to replace the whole shebang next time I'm down. Probably could have eeked out another year or four of service life from the part if I didn't idle the engine.


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## JohnRPollard (Mar 26, 2007)

beej67 said:


> I heard one guy say (maybe on here) that he ties his engine key on a string, and hangs it on his thru hull valve whenever he shuts it, to remind him not to start the engine without opening the thru hull.


Hey, that's me. When you're a knucklehead, you have to take these sorts of precautions.....


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## TSOJOURNER (Dec 16, 1999)

ok found the second blade, it was blocking the hose going into the heat echanged and visible after removing the hose from it... my pliers were too small to get in there so I took the cap off, easy enough but it was on there tight, got a small cut trying to pry it off (auch). I also noticed some white residue around some of the openings and around the cap so I cleaned that up and put it back together.... I'm calling local yanmar to see if they have the prebent version it does fit snuggly in there.

Love the tip on tying the key to the valve, I never forgotten it but sometimes I'v been close. Hopefully tomorrow I'll have my pump, install it that evening and it will be all back in working order, I replaced both belts and kept the alternator as a spare, threw the raw water belt away as I got a new one with the pump. I'll update on how it goes... thanks all !


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## JohnRPollard (Mar 26, 2007)

Well done! Glad it worked out for you and that you were able to recover the other impeller fin.

Please don't forget to post the contact info for that alternative supplier on the raw water pump, when you have a chance. Thanks.


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## TSOJOURNER (Dec 16, 1999)

hey all, got the pump today and before heading down there I compared the numbers and its the exact same pump I had before... If this one last another 10 years I'm fine with that over $350 more for the newer. the vendor is Bay shore marine in Annapolis and I couldnt find a pump at a cheaper price. also got a belt and a extra impeller/gasket with it so I should be all set. thanks to everyone for helping me thru, installing it was easier than taking it off and the engine purrs nicely with more than ever spashing.

thanks !


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