Motor died. Two mysteries. Is it the snap ring on the impeller?

[capnward]

The new Moyer 502 flange pump you ordered has no snap ring at the impeller, no grease cup, and no gasket. Only a tiny O-ring. It's better to have the rebuild kit on hand in case you develop a bad leak, then you can fix it on the spot instead of waiting several days for the kit to arrive. The kit does not include a new pump housing or backplate. It does include new O-ring, impeller, bearings, seals, shaft, grease, and directions. https://moyermarine.com/product/repa...p-csob_00_461/
If your experience is like mine, you have four years before you will need to rebuild the pump. But I run the A4 100 hours a year or more. Replace the impeller every two years, more if you use the engine a lot. The snap ring on the old pump was there to keep the impeller from wearing out and forcing water past the seals.

[ernst]

The new Moyer 502 flange pump you ordered has no snap ring at the impeller, no grease cup, and no gasket. Only a tiny O-ring. It's better to have the rebuild kit on hand in case you develop a bad leak, then you can fix it on the spot instead of waiting several days for the kit to arrive. The kit does not include a new pump housing or backplate. It does include new O-ring, impeller, bearings, seals, shaft, grease, and directions. https://moyermarine.com/product/repa...p-csob_00_461/
If your experience is like mine, you have four years before you will need to rebuild the pump. But I run the A4 100 hours a year or more. Replace the impeller every two years, more if you use the engine a lot. The snap ring on the old pump was there to keep the impeller from wearing out and forcing water past the seals.

Ah, that sounds much better. Let's see, if you have >400 hours time between failures, that is for me, ehm, about a lifetime Most years I run the A-4 maybe 10 or 15 hours.

Snap ring: So it seems the wisdom I gleaned from the internet ('snap ring is only used for transport') was wrong! It may not be by chance that the pump worked fine for at least 18 years (plus the time it was in there before I bought the boat), and then failed after it ran for a few hours without the snap ring. Exactly in the way you describe it: forcing water past the seals.

I guess I learned an expensive lesson

[ndutton]

Snap ring: So it seems the wisdom I gleaned from the internet ('snap ring is only used for transport') was wrong!(

Do you remember the source of the wrong information? Sailboatowners or one of the Catalina forums?

[ernst]

Do you remember the source of the wrong information? Sailboatowners or one of the Catalina forums?

No, I don't remember. Definitely not Catalina.

[ndutton]

OK, thanks. I asked because there's a guy who frequents both SBO and more than one of the Catalina sites who advocates discarding the Oberdorfer impeller snap ring for exactly the reason you read on the internet.

I'll stop there if you get my drift.

[ernst]

OK, thanks. I asked because there's a guy who frequents both SBO and more than one of the Catalina sites who advocates discarding the Oberdorfer impeller snap ring for exactly the reason you read on the internet.

I'll stop there if you get my drift.

Thank you. I may have been on SBO at some point but I don't recall ever going to a Catalina site. Or maybe it spilled over from there into other forums?

[ndutton]

Thank you. I may have been on SBO at some point but I don't recall ever going to a Catalina site. Or maybe it spilled over from there into other forums?

Entirely possible. That's how misinformation spreads, people repeating what they read without any specific knowledge of their own.

[ernst]

Entirely possible. That's how misinformation spreads, people repeating what they read without any specific knowledge of their own.

I have to admit I wasn't that smart either I did not spread any misinformation but on the face of it this story clearly holds no water. Why would you need to secure an impeller 'for transport'? I guess it is something I wanted to believe since it is a minor pain to deal with that thing. Oh well, now I need to deal with the consequences.

In principle installing the new water pump should be very straightforward: just two bolts! It is a bit more tricky in my installation since I have the Indigo FWC system. The bracket that holds the raw water pump partly obstructs one of these two bolts. I will have to see how much disassembling this will require.

[ndutton]

. . . . on the face of it this story clearly holds no water. Why would you need to secure an impeller 'for transport'?

Well, without the snap ring it's possible the shaft could slide out of the pump during transport but that would require it to be shipped in a box with one dimension over twice than what is necessary. You're right, it's a ridiculous premise yet the internet experts persist.

[ernst]

Well, without the snap ring it's possible the shaft could slide out of the pump during transport but that would require it to be shipped in a box with one dimension over twice than what is necessary. You're right, it's a ridiculous premise yet the internet experts persist.

Yeah, and if such a packing size would have to be used (why??), two inches of packing tape would serve just as well.

[ernst]

Thanks, Al and John! The order will go out to Moyer today or tomorrow.

Here is my latest update. Last weekend I finally had the time to tackle the installation. It went mostly up to plan except for one snafu: I have the Indigo FWC system and I knew that the pump installation was a little bit more involved than just loosening two bolts because one of them holds the bracket for the raw water pump. I was prepared for that but not for the fact that the bolt that was used for that was too long to fit between the pump body and the hole where it is supposed to go. It turns out that the MMI pump has a slightly thicker flange (by about 2mm) which creates this interference.

My first idea was to cut off the bolt but I thought I check with Tom Stevens before doing that. He answered again within a couple hours (!) and pointed out that I am already loosing about 2mm in length because of the thicker pump body. He suggested instead to grind down the pump body.

Of course this made a lot of sense. So this is what I did. After that, everything went very well (OK, there are always things that go wrong: I actually overshot a bit with my grinding and as a result, the fan wheel of the alternator started striking the sheave of the belt, requiring repeated taking apart of the whole thing until I had everything back to where it needs to be). The pump is working very well now.

There is, however, a new problem: I noticed a tiny weeping of oil at the flange. It is really minuscule but I do not want to have any oil going into the bilge. I tightened both bolts as much as I dared (and that is really very tight!) which made the leak even smaller but it did not go away. I was flabbergasted and had no explanation. I ran out of time and in the car on the way back I found a possible explanation: I had mounted the pump dry, using just the gasket provided. But the old pump had quite a bit of gunk at the flange, some goop someone (not me) had used with the old gasket. I realized that I had scraped that off on the pump side (in case I will use it as a spare) but not on the motor side! So I wonder if there is some of that stuff on there, preventing a tight fit.

So I guess I have to take everything apart again and clean up the motor side of the flange. But before I embark on that project, I have two questions: Assuming that my idea is correct, that there is some dreck on the flange, did I ruin the new gasket? Should I pre-emptively order a new one? And second, I mounted it dry. Should I put some goop on the gasket when I mount it again?

Thanks for any advice!

[ndutton]

1. Gaskets should always be installed on clean mating surfaces
2. Gaskets should never be reused
3. Generally speaking, gaskets do not require additional sealant
4. Grinding down the flange of a new MMI 502 flange pump - ugh! You may have little choice because you're combining components from different manufacturers but still, ugh! I realize it's too late now but a threaded stud in the accessory drive hole with a hex nut to fasten the pump and bracketing could have solved the misfit.

[ernst]

1. Gaskets should always be installed on clean mating surfaces
2. Gaskets should never be reused
3. Generally speaking, gaskets do not require additional sealant
4. Grinding down the flange of a new MMI 502 flange pump - ugh! You may have little choice because you're combining components from different manufacturers but still, ugh! I realize it's too late now but a threaded stud in the accessory drive hole with a hex nut to fasten the pump and bracketing could have solved the misfit.

To your first 3 points: OK, I will order a new gasket then.

Your last point: All I can say is FACE-PALM!! Why did I not think of that!!!

[ndutton]

Your last point: All I can say is FACE-PALM!! Why did I not think of that!!!

You didn't have to, that's why we are here. I wish you had mentioned the earlier advice on the forum before reaching for the grinder though.

[ernst]

You didn't have to, that's why we are here. I wish you had mentioned the earlier advice on the forum before reaching for the grinder though.

Believe me, I wished I had, too!