Drip from Water Pump

[ejay]

Just finished a long trip off Ca Coast and A4 worked great! However I noticed a small drip for the bottom of my MMI water pump, which produces a lot of water in the bilge over many hours. The drip is not coming from the attached hoses.

So my question is, should I just replace the impellar and the o ring on the backing plate? Or should I worry about something more serious within the pump structure?

EJ
78 Cat 30

[Dave Neptune]

Your pump is probably leaking from the shaft seal in the back of the pump. Replacing the seal is recommended any time you replace the impeller IMHO.

If you have decent access it is easier to redo the pump on a bench if not get the "MMI extended bolt" so you can remove easily for regular maintenance.

Once apart check the shaft if it has a grove worn into it replace the shaft to or you can upgrade to the new style pump.

Dave Neptune

[Golfdad75]

Leaking from weep hole

At what time would you decide to buy another water pump as to rebuilding, I have a Nabisco 1673 that I rebuilt 3 years ago

[ejay]

Thanks Dave! So my next question is whether I should try to rebuild the pump with the kit from MMI at $136 or just buy the new one at $300. I wonder if anyone has a video resource regarding the rebuild process? I did not see anything on the tech tips page and my MMI manual is on my boat right now.

EJ
78 Cat 30

[hanleyclifford]

Thanks Dave! So my next question is whether I should try to rebuild the pump with the kit from MMI at $136 or just buy the new one at $300. I wonder if anyone has a video resource regarding the rebuild process? I did not see anything on the tech tips page and my MMI manual is on my boat right now.

EJ
78 Cat 30

You should buy a new pump from Moyer Marine so that you will have a spare if trouble comes where and when you have no choice.

[ejay]

I found the excellent Don Moyer video on the rebuild process. I will buy the kit and attempt the project on a bench next week.

[joe_db]

I bought a new one. No more worry about the grease cup AND the old one still pumps water even if it leaks, so I have a get-home spare.

[ejay]

Good point about having a spare pump, as I have never really thought about the fact that the water pump could fail. I have spare impellar on board, but not an additional pump.

What is the risk of something other than the impellar failing, so that an additional pump would be needed?

[hanleyclifford]

Good point about having a spare pump, as I have never really thought about the fact that the water pump could fail. I have spare impellar on board, but not an additional pump.

What is the risk of something other than the impellar failing, so that an additional pump would be needed?

If the pump is for antifreeze the risk is minimal but if you are pumping raw sea water there is an elevated risk of scoring in the impeller housing. Another consideration is access. If you can comfortably replace the impeller faster than doing a full pump change you have an advantage. I prefer rebuilding a pump on the bench and if you do long range cruising you need to consider availability of location where you can disable the boat safely and conveniently while you work. I carry both spare pump and spare impellers. It's nice if both pumps are Moyer products sharing many parts.

[ejay]

I got the pump off today. In the picture you can see corrosion from the leak coming from the opening under the pump. Is this consistent with a bad shaft seal?

[Dave Neptune]

Yep, that's about the only way the water can get there. Do check the shaft for wear where the seal contacts it.

Dave Neptune

[Al Schober]

That looks like the new Moyer pump with the face seal vs the two lip seals. That looks like a shielded ball bearing at the engine end of the pump, and there is no grease cup. I haven't rebuilt one of those but it is certainly worth doing. The kit for the Oberdorfer pump won't do you any good!

[ejay]

Any advice about how to get the stuck on gasket off without damaging the metal?

[Dave Neptune]

Only way I know is a good sharp scraper with no nicks. Leaving a few scratches won't really hurt as that is why the gasket is soft material for sealing irregularities and the sealant does the rest.

Just be careful is really about the only advise I can think of.

Dave Neptune

[ejay]

Permatex sealant between gasket and pump?