Yanmar fresh water pump

[TommmD]

HI, I have a Yanmar 3GM30F, & have been noticing a small cooling leak after running several hours. The fresh water cooling pump has a weep hole & it is weeping (!). Does appear to be increasing, perhaps 4 ozs after several hours motoring. Getting ready to replace it, wondering if someone can fill in the gaps in my understanding what is happening.

[DeborahLee]

The shaft seal is worn. Best replace the whole pump instead of rebuilding. Better check your reservoir if pump is leaking that much before it stops leaking..

[phantomracer]

i replaced mine on my 92 3gm30f. the pump is in 2 sections, the pump and some sort of bracket thingie. Most places will sell you both as a unit. I got the pump alone and installed it. (Paint it before you install it , if you care about that). ensure you torque the bolts properly, and check the torque some time later. Not a hard job by any means.

Got to ensure the bracket to engine gasket stays intact , or that has to come off and anew gasket installed there too.

Unsure if yanmar requires silicone gasket sealer, but i installed the waterpump gasket dry.

[Gary Mc]

I got a rebuild kit for the fresh water pump on my 2GMF for $85 usd and rebuilt it and it has been fine for 8 years. I would compare cost difference for the kit versus the whole pump and depending on how much you like fixing things maybe go this way. There is a small cir clip in the middle of the pump shaft that is hard to see but needs to be removed to allow the shaft to come out.
Good luck

[Captndave1]

Go to any bearing supply store and you can get new bearings and seals for under$20. easy peasy to replace.

[ramblinrod]

Originally Posted by TommmD

HI, I have a Yanmar 3GM30F, & have been noticing a small cooling leak after running several hours. The fresh water cooling pump has a weep hole & it is weeping (!). Does appear to be increasing, perhaps 4 ozs after several hours motoring. Getting ready to replace it, wondering if someone can fill in the gaps in my understanding what is happening.

Ok first off Lets verify terms. Many people confuse freshwater vs seawater systems and components.

The freshwater system, is the one that is a closed system and you put put water and coolant in, and has a reservior.

The seawater system is the open system that takes water from outside the boat and discharges it through the exhaust.

(I find people who sail freshwater lakes often reverse this.)

The seawater pump has a weep hole that will drip if the shaft seal is leaking. The 2 component shaft seal is very inexpensive and easy to replace. If your impeller hasn't been replaced in 4 years do it at that time, and if the original shows no sign of wear, keep it as a known correct and working spare. In a jar full
of water is best.

If it is in fact the freshwater pump, replace the whole thing. Keep the old one as a leaking but known correct spare, should the bearing ever catastrophically fail in the new one. Best to spray it with oil and seal it in a plastic bag.

Rod Brandon
Sheen Marine
Yanmar Dealer

[wsailing1]

I replaced my fresh water pump(closed system -antifreeze) yesterday(same yanmar engine). Cost was $103 from yanmar. I also replaced the 2 hoses. All were original- 20 years old. It took about 2 hours. The weeping shows the seal has failed just like older car engines.

[wannacat]

WSAILING1, could you please state the Yanmar part # or model # of the replacement pump you purchased for $103? Also, which dealer did you purchase it from? I've had quotes for hundreds more!?!?!? I have the 2GM20F engines and would love to purchase a spare freshwater pump. Even the raw [saltwater] pump has been quoted to me for far more than your price. Send me a PM or just post the info here. I'm sure many of the members would be interested in attaining one for that price. Thanks!!!

[tailgnner32]

Yanmar no longer sells rebuild kits for that fresh water pump.
The Yanmar part # for the pump is 121000-42100 $108.10
The part # for the gasket is 121000-42051 $3.71. That pump will fit both the
2GM20F and 3GM30F, I just changed mine not long ago, call Complete Yacht Service
in Fort Lauderdale, they can help if need be.

[phantomracer]

I was told you had to buy 728695-43500 with it. neimic marine sold me the pump alone. Worked fine. The bracket to engine may come loose and need a gasket for that if it tears.

[wsailing1]

I've been on an offshore trip. Pardon the delay. As the thread says above the part # is 121000-42100. Cost was actually $110. I alao replaced two hoses and the gasket.

[GordMay]

Greetings and welcome aboard the CF, Tailgunner.

[tailgnner32]

Sorry my post is a day late, 728695-43500 is the body between the f/w pump
and the engine block, that should be fine, but the price on that pats is $167.64
If you feel you need that as well, you can buy the pump and body together
part # 128695-42010 for $244.88, you will also need gasket # 121450-44411 at a price of $2.15

[tailgnner32]

Thank You, Gord May!

[TommmD]

Late getting back to this thread, but yes, you will need the thermostat housing to block gasket, which I did not have this w/e. Much nashing of teeth.

The pump comes as just the pump, you keep the pulley & bolt it back on. I need to figure out how to hold it so it doesn't spin. Pulley has to come off to torque the bolts down.

I got mine from from Niemiec Marine also, but they can only sell to a specific region. Mack Boring is the parent, I believe.