Impellers - aftermarket or OEM?

[jviss]

Winterizing my boat last Fall I had the raw water impeller fail, and installed my only spare, an OEM Westerbeke unit. (Fortunately I found all of the pieces of the failed impeller in the heat exchanger.). So, I need a spare. I bought an OEM impeller "kit" at the boat yard, with an impeller, a pack of grease, an O-ring, an two spare cover bolts. $44.10, which is, I think, list price. Then I found an aftermarket kit on eBay for $17, so I bought that, too.

What do you guys think? Is there a good reason to stick to OEM, or are aftermarket just as good? Any horror stories?

Thanks,

jv

 

[odaydokay]

I would be surprised if we have, collectively, enough experience/data to make a call on this one. My personal call is when it is a "mission critical" item, I pay the extra for the OE part.

 

[kappykaplan]

when it is a "mission critical" item, I pay the extra for the OE part.

 

[Rich Stidger]

I don't think Westerbeke, or any engine or pump manufacturer makes their own impellers. I use Johnson impellers in my aux and genset. No problems or shorter life at all.

 

[Stu Jackson]

I don't think Westerbeke, or any engine or pump manufacturer makes their own impellers. I use Johnson impellers in my aux and genset. No problems or shorter life at all.

Rich is right. Westerbeke doesn't make pumps either. So what pump is it? Johnson, Sherwood, Oberdorfer?

 

[Rich Stidger]

Then I found an aftermarket kit on eBay for $17, so I bought that, too.
Any horror stories

@jviss , actually since you have a Westerbeke, you should know that depending upon the exact pump model, Westerbeke pulled a nasty change. If you have the old style pump #33636, it uses impeller #34440 which is a "standard" Johnson impeller. (Think aftermarket)
BUT, if you have the new style pump #48080, it uses impeller #48500. The impellers look the same, but Westerbeke made the slot in the new style pump shaft just a bit smaller so that the old style impellers, and consequently the standard Johnson impellers can't be installed. Thus forcing you to buy their high priced impeller kit.
That's not very nice.
But you can fix the mis-match by simply swapping the drive pin from an old impeller into a new one. Or if you have a lathe you can remove the pin and turn it down to 0.155 from 0.190.
Bad Westerbeke.
I learned this while struggling to install a new standard impeller into the new style pump. I was not pleased.
So what I do now is to remove the pin from new Johnson impellers, machine them down to 0.155 and reinstall. Then I mark the box so that I know the impeller is ready for immediate use.

 

[jviss]

I have the pump that uses the 48500 impeller, but even so, there's an updated pump for this engine that I don't have. I don't know who makes the pump that I have.

 

[Rich Stidger]

I have the pump that uses the 48500 impeller, but even so, there's an updated pump for this engine that I don't have. I don't know who makes the pump that I have.

I think Johnson makes the Westerbeke's pumps. Be sure to compare your OEM impeller with the aftermarket that you bought for drive pin size.

 

[jviss]

I think Johnson makes the Westerbeke's pumps. Be sure to compare your OEM impeller with the aftermarket that you bought for drive pin size.

I will, thanks.

 

[BarryL]

Hi,

A number of years ago I bought one of the blue 'globe' impellers that was supposed to be able to 'run dry' without damage. The impeller failed after one year. I normally get 3+ years from an impeller, and to be honest, the globe impeller is the only one to EVER fail on me. I usually just change impellers after 3 years.

Barry

 

[jviss]

I used to change impellers every year. I stopped doing that several years ago, as I noted that the impellers I was removing seemed fine. This one went too far, and, admittedly, ran dry for a minute while I was winterizing, and failed. So, I will go back to at least inspecting them annually, if not replacing them.

 

[LakeOntario270]

I use Sierra 23-3307 for my Westerbeke 20B Two

 

[jviss]

Rich is right. Westerbeke doesn't make pumps either. So what pump is it? Johnson, Sherwood, Oberdorfer?

You know, good questions, Stu. It got me thinking. I can't find the box from the impeller I installed in the Fall. Now I'm wondering why I think the 48500 kit is correct. I'm going to trial fit it to make sure my spares are correct.

Thanks.

 

[jviss]

Ah, sugar! My mind is slipping....

I just found the box for the last impeller I installed, and it's a 34440, not 48500. Oh, well, I can return the expensive one to the boat yard, or better, exchange it for the right one. The eBay purchase is probably a throw away. But, then, the eBay description is "Impeller for Westerbeke Flange Mount Marine Engine Water Pump 48500 34440." Could this mean the impeller is the same, but that perhaps the difference in the kits is an O-ring vs. a gasket? I'll compare the impellers when I get it. And, more old age brain stuff, last year I had already purchased a spare from StayCoolPumps, so I have that on hand! But, it wasn't on the boat - a lot of good that would have done!

I was thinking. Wouldn't it be a good idea to have dual redundant seawater pumps? Perhaps a backup that's electric? And, maybe drawing water from a different through-hull, as cooling water failures are often due to blocked through-hulls?

Anyway, now that I have an OEM and an aftermarket impeller, I can at least visually and tactilely compare them, and see if I can detect a difference.

Anyone have any experience with those run-dry impellers besides @BarryL ?

 

[Rich Stidger]

@jviss - If your pump uses a gasket, then it is the old style #33636 and it uses the #34440 impeller with the 0.190 diameter drive pin.

If your pump uses an o-ring, then it is the new style #48080 and it uses the #48500 impeller with the 0.155 diameter drive pin.

Since you installed a new-style impeller, you could have either pump. The new style impeller #48500 will still fit into the old pump, but it will have a bit of slop at the drive pin.

I looked at the eBay listing and the impeller pictured has a threaded rod for the drive pin. In my experience that is the size of the old style impeller, and it will only fit the old style pump, regardless of what eBay claims. So if you have the pump with the o-ring, you will need to cut down the pin to fit. Since the pin just screws into the impeller, just remove it and chuck it in a drill. Use a file to remove enough metal to get the diameter down to 0.155 and then replace the pin.

 

[jviss]

Thanks Rich. I am going to have a closer look today. Since moving and retiring it's nice that the boat is only 20 minutes away.

 

[Dalliance]

I can’t comment specifically on blades for your Westerbeke, but I’ve been using Jabsco impellor blades in my Yanmar for almost twenty years. I’ld be real suspicious of eBay bargains. They’re often inferior knockoffs and no bargain in the long run. It’s a critical part. Just buy known quality and stay on a regular maintenance schedule.

I check mine every spring and replace the blade with a brand new one every other year regardless. The two year old blade, which always comes out looking new, then becomes the emergency spare for two years. Knock on wood, I’ve never had an impellor blade fail. Replacing them on a regular schedule is cheap insurance.

 

[odaydokay]

I used to change impellers every year. I stopped doing that several years ago, as I noted that the impellers I was removing seemed fine. This one went too far, and, admittedly, ran dry for a minute while I was winterizing, and failed. So, I will go back to at least inspecting them annually, if not replacing them.

When you pull the cover off just to inspect, does this not tear/beat up the flimsy paper gasket or do you find you can just put the cover right back on, maybe with a tad bit of dishwashing liquid?

 

[jviss]

When you pull the cover off just to inspect, does this not tear/beat up the flimsy paper gasket or do you find you can just put the cover right back on, maybe with a tad bit of dishwashing liquid?

You know, I can't quite recall at the moment, but if my memory serves me well, I have an aftermarket Speed Seal cover that uses thumb screws and an O-ring.

In any event, new impellers come with new gaskets, and I've accumulated quite a few, in addition to the extras that were in the Westerbeke parts box when I bought the boat.

The newer pump Westerbeke recommends uses an O-ring, too.

 

[odaydokay]

Now you got me wondering too, so I went to the Oberdorfer fact sheet I had from when I bought it to replace the old Sherwood. My N202 pump has an o-ring, but all impeller kits contain a paper gasket also, so that is what I saw. They supply that for the older models that used paper. For mine, it looks like I can just pull the cover off and look at the blades ("take attendance" for one thing) and slap some Dawn on the o-ring and move on assuming all looks ok. I have a few years on it, but a total of not so many runs.