Leaking raw water pump

[Ed Caldwell]

My Yanmar raw water pump appears to have sprung a leak. In the post-shutdown check yesterday, I found about a half cup of water in the catch basin below the engine. Today I ran the engine with the hatches open and found a slow drip, 1 drop about every 1-2 seconds, from the bottom of the pump behind the pulley. The hose clamps appear to be tight and dry. I pulled the pump off, and found the impeller looked good, the o-ring looked fine (although there was some small trash in the groove on the housing). The pulley has no apparent play and there isn't any bearing noise at hand spin speed. The engine is the 27 hp 3GM30F (I think that's the number) with about 350 hours in 4.5 years. Any reported problems with this pump failing so soon, especially without any play indicating bearing/seal wear? Is the pump cheap enough to just swap out or should I replace the impeller and o-ring and ensure the cover is nice and tight to see what happens? No problems with water leaks until this weekend...EdS/V GraceHunter 340

 

[Rob]

Could be a few things

Ed,I had a similar problem with my waterpump on my YSM12 - the cooling system was losing it's prime because air was enterting the system at the pump. It would/should not be the impeller. They leak either at the shaft seal/o-ring or the cover plate could be worn down. Mine was the shaft seal and a rebuild kit was just a few $ less than a whole new pump so I decided to just replace the entire unit (~$300).Be careful air doesn't get into the system causing the pump to lose it's prime....engine will overheat.Good luck and take this only from my experience...I am not a mechanic.Rob

 

[Martin]

Same Problem

I have the same problem with the same engine. In a previous thread someone referred to a "weep" hole leaking at the bottom of the pump. According to the respondents on the thread the bearing seal was leaking and the pump needed to be rebuilt. I checked with my local Yanmar dealer and there is no rebuild kit but all the parts could be ordered seperately. The clerk noted that a new pump costs less than the sum of the parts. Around $250. Anyway, I was planning on replacing the pump. Any other ideas? The "weep" hole makes sense as that is where the water seems to be coming from.

 

[Paul (Affinity C320)]

Changing the Impeller

While we are on this subject, on the 3GM30F, what is the best way to change the impeller? Looks like the pump needs to come off -- is that right? Can't help you with the leak but looks like you have experience. This is my first full season with the boat and I just want to change the impeller for insurance.Thanks,Paul

 

[Ed Caldwell]

remove the pump

It's easy to do on my engine. Ensure the raw water intake thru-hull is closed! Loosen the two mounting bolts. Pivot the pump down to loosen the drive belt from the pulley, move it out of the way, then remove the hose clamps. You'll get some water draining out of the hose and pump (you did remember to close the thru-hull?). Finish removing the bolts and the pump comes right off. Changing the impeller is now a table top job.

 

[Fred Ficarra]

And don't forget which way the pump mounts

It can be reinstalled backwards and it'll look just fine. The problem is, it won't pump. Trust me.P.S. I carried a rebuild kit for my 3GM30F raw-water pump for several years. It was sold on a blister pack. You know, clear plastic vacuum sealed on cardboard. All components of the pump were in the kit except the housing, shaft and rear plate. It cost $99.00. That'll tell you how long ago I bought it.

 

[Jared]

Me too.

I have the exact same thing... I just bought a new oil seal and water seal and will go that route this weekend. They are on the pully side, not the impeller side since I had no leaking at the back plate. I will let you know if the leak stops after I replace these two pieces. I am not sure how much they are, but I am sure that it is not horribly expensive and would seem to be the most logical leak reason from what I can tell. But, like someone else said, I am no mechanic... I'm keeping my fingers crossed.

 

[Big Windy]

3GM30F Impeller

It is an easy job to get to the impeller. Pull off the water pump and the impeller is just behind it. There are six screws that hold the impeller cover in place. I pulled mine off, looked at it and put everything back...it was in good shape.

 

[Bill C320 Papillon]

same situation different engine/pump

I sent my raw water pump in for rebuilding over the winter. I got it back in December but didn't install it until a couple of weeks ago. It leaked worse than before. I sent it back to the company , they tested it,could not make it leak and sent it back. I reinstalled it a week ago, still leaks.I tested it by making up a hose that fit the "in" side on one end and fit a garden hose on the other. I made another short section that I put on the "out" side. Turned on the garden hose and and squeezed off the "out" hose. No leaks with probably more presure than the pump generates when it is pumping. I put everything back together and still leaks (only less). I'm convinced that the leak is actually at one of the hose connections but appears to be comming out of the "weep hole". I'll get new hose clamps and square off the hose ends to see if that fixes things.I envey you in that apparently your pump is easy to remove. You have to be a snake to get to a couple of the bolts on mine, it is a reall PITA.From the sounds of some of the responses, it sounds like your pump is belt driven ( mine is gear driven) and I have been told that if you tighten the belt too much, you can put a strain on the impeller shaft that can cause water to get past a seal on the shaft. Might check that out too.Good luck

 

[Jared]

Grease question

When I put this thing back together, everything should get greased up pretty well, correct?What type of grease does everyone use to do projects like this? Thanks.Anyone else tired of messing with their engines and just want to get out on the water!!!! I got so mad this weekend, I just put the dinghy in and took it for a spin just to say I was on the water.

 

[Paul (Affinity C320)]

Grease

When I pull the water pump apart, I always put white grease in there. It is all going to wash away but makes me feel better knowing that when I test fire the motor, there won't be any danger, I can then proceed to put the boat in the water knowing the motor is not going to let me down. Only failed to start one time, missed my launch till the next day. some how, during the winter a wire came off, just had to figure out where it went. Best of luck.Paul

 

[Ed Caldwell]

New pump ordered

To close out this thread...I ordered a new pump from the "local" Yanmar distributor. About $220 plus shipping. No repair kits available from them, plus I was discouraged by the experience of the responders on getting the bearing/seal in just right to avoid an onging leak. I'll keep the old one for an emergency spare, slow drip and all.

 

[Ed Schenck]

Raw water pump fix.

No one has specifically stated this so I wonder? Do you all have pumps driven by the same belt as the alternator? I would have thought the newer boats would have a separate drive for the waterpump.Bill alluded to the strain on the pump shaft. A too tight belt will definitely wear the bearings and seals much too fast. This seems to happen especially when owners install the high amp alternators. Then they have to tighten the belt to prevent slippage. There goes the water pump.A relatively inexpensive fix is to add a drive pulley on the front of the current one. My 2QM20 actually has bolt holes. Then offset the waterpump to align with the new pulley. The offset holes will be slotted so that you can adjust the tension. The waterpump will turn with 1/4 the strain it takes to run the alternator. Although I have never really investigated it would seem an electric pump might be an easier option. I find the current rebuild kits do not seem to last as long as the original pump. But I carry the one that I rebuilt as a spare. Mine is a Perko.

 

[Ed Caldwell]

Mine is separate

There are two belts on my engine (1999 vintage). One for the alternator and the other for the raw water pump.

 

[Stu Jackson]

Ed's right

He wrote: This seems to happen especially when owners install the high amp alternators. Then they have to tighten the belt to prevent slippage. There goes the water pump.The idea is to buy a highER output alternator that won't over tax your belts and pump.Stu