Leaking raw water pump

[Trekka]

Originally Posted by Chief Engineer

Depco Pump Company

They are the most expensive of a half dozen suppliers I found on the web. $492 for a new pump vs $344. I'll pay for service and support, but that is just an item in a box.

So far nobody has rebuilt units. (I am open to suggestions on where to look). If I have no alterntives by tomorrow I'll order the repair kit from a store that has it for $87 and do the work myself. (Another skill to achieve... task to have performed... on the great checklist of... boat ownership)

[Trekka]

Well, two different companies that list the repair kit "in stock" for under $100 did not in fact have one - and couldn't get one for at least a week.

So I ordered one at a higher price + 2 day shipping, about $135.

So I know what I'll be doing this weekend.

[Tropic Cat]

Originally Posted by Trekka

So far nobody has rebuilt units. (I am open to suggestions on where to look). If I have no alterntives by tomorrow I'll order the repair kit from a store that has it for $87 and do the work myself. (Another skill to achieve... task to have performed... on the great checklist of... boat ownership)

The problem is that fine grit works it's way in between the shaft seals and the shaft. Not only does the seal leak but as the shaft spins the grit acts as an abrasive and a groove forms in the shaft. In most cases, new seals will not seal against these grooves. I'm guessing that this influences the number of rebuilt units available. I would strongly recommend removing the pump and seals and inspecting the shaft before you spend your $87.00

[S/V Antares]

Ditto on inspecting before buying the kit. If the shaft is groved you could be wasting your money. Buy a new one and keep a rebuild on hand if you are cruising. If you have the dimenions you can find generic seals on line.

[Trekka]

Ok, I got the kit, I have removed the impeller, undone the 4 bolts and the hoses - and the pump won't budge. I've tried tapping it with a rubber mallet, but because of where it is on the engine I can't get a clear knock on it from the back.

Suggestions on how to get this pump to let go of the engine?

[Maddog]

PB Blaster and wait a day. Take a large screw driver and tap the joint with a hammer all around. Once you get frustrated, get a bigger hammer and indulge in self-therapy.

[Trekka]

Well, PB Blaster and a few days waiting, a little wiggling the tiny separation with a thin blade, more PB Blaster, a whole bunch of raps with a ball peen hammer in the two places where I could get a 3-4 inch swing, more waiting, more wiggling the crack, more raps, and it's finally off. Dang gasket had turned into glue.

Now to try the rebuild and see if the directions make sense.

Btw, while waiting for the PBB to work I took off the reservoir, a couple pipes and hoses to add to my collection for cleaning at home. Lot's of slime in the coolant plumbing.

[Astral Blue]

Holy thread revival! I seem to have a similar but slightly different dilemma. Rather than starting a new thread, I thought I'd add to this one.

I have recently repowered with a Perkins 4.108 equipped with the Sherwood G65 pump. This engine was from British military surplus and had been built in the mid 1980's but never put into service. The impeller and seal fitted on the engine was the original one, being about 30 years old.

Before placing the engine back into service, the impeller and seal was replaced. After replacing them, we had about an hour of bench test time (boat out of water) and discovered no leaks.

We placed the boat in the water and ran the engine. Within a few minutes, water started dripping out of the weep hole. There is about one drop every 5-10 seconds.

My mechanic was the one who replaced the impeller and seal, so I have very little knowledge of how it was performed.

Here is my first (and only) suspicion as to what might have gone wrong: the seal might have been installed backwards. From what I understand and have been told, the spring on the seal should face the impeller and the flat section should face the engine. Is this correct? And assuming the seal was installed backwards, is it possible to remove and reinstall it...or does reinstalling it compromise its ability to keep water out?

And finally, is there any other condition I should look for or be concerned about with respect to finding possible causes of the leak?

Thanks in advance for your help.

[perchance]

Removing seals usually destroys them as they are somewhat fragile. Seals are either inclusion (keeps stuff in) or exclusion ( keeps stuff) out. You can tell by which way the lip is leaning. As far as scoring on the shaft goes you can install the seal deeper into the seal cavity to avoid the worn area if the cavity is deep enough. If you have the pump off change the bearing(s) while your at it. The leak will have rusted it anyway.

[noelex 77]

Wow what an old thread to revive.
It is however a very common problem. The seals on a salt water pump are a common failure item. The seals are very inexpensive and replacement is easy, but if you have never done it before it can seem complex.
Here is resource that should make it easy.

Water pump

Mainsail who is regular and valuable contributor to these forums has a great website that covers rebuilding the water pump, but my Internet on the boat cannot find this, but its worth a search.

[pdxsailordiver]

Originally Posted by Trekka

Well, two different companies that list the repair kit "in stock" for under $100 did not in fact have one - and couldn't get one for at least a week.

So I ordered one at a higher price + 2 day shipping, about $135.

So I know what I'll be doing this weekend.

Seals and bearings in those pumps are nothing special. Find yourself a good industrial bearing supplier like McGuire Bearing .
I think last time I rebuilt the one on my 4-107 I spent $35 and got enough for 2 rebuilds. Just make sure the shaft is not worn.
Tim

[DeepFrz]

Compass Marine's Photo Galleries at pbase.com

[Astral Blue]

I pulled the water pump off today and took it apart. As noted in my earlier post, my mechanic was the one who replaced the impeller and the seal. To my surprise, I found everything in the impeller housing coated with grease. It is my understanding that the part of the shaft that the impeller fits on should have a mild coating of grease in order to easily enable its future removal. The impeller, seal (both sides), seal spring, etc, were coated with a very generous amount of grease.

I suspect the generous amount of grease found on both sides of the seal and its outer perimeter compromised its ability to keep water out. I removed most of the grease, reseated the seal, reassembled and reinstalled the pump. I hesitated to use a degreaser or Gunk due to concerns it might damage the rubber components.

Well, 80% of the leak has been eliminated. I guess this is a good first step. My next step is to order a new seal, remove the pump, disassemble it, remove the old seal, remove more grease, and install the new seal. Hopefully, this will eliminate the water leak.

With that said, I have a few questions...

1. Does grease compromise the seal? I hope I'm on the right path by suspecting it does -- as the leak could have subsided simply by my reseating the seal.

2. If grease is the culprit, what chemical(s) will be able to safely remove it without damaging rubber components.

Thanks in advance for any help.

[DeepFrz]

You should use a light coating of Slippery Stuff (or other water soluble lubricant) around the impeller housing and even on the impeller blades. You certainly don't need a thick layer of grease. In fact grease may harm the impeller, although I am not sure of that.

It does sound like there is something wrong with the seal or shaft though.

Just wipe off the grease with a rag or wash with a dish liquid and rinse thoroughly, dry and then apply the lubricant.

[Albro359]

The other issue is the shaft itself....
IF you have had a worn seal for long time you may find that the shaft is actually scored.
Replacing the seal on a scored shaft does little except wreck the new seal...
Check the pump shaft for scoring is my ...what do you yanks say ?...two penny worth..or ???