How often do you replace your impeller?

[Baltimore Sailor]

Yeah, but I still haven't bought that extra shaft and fittings.

One of these days, though...

I did finally put in that MMO-soaked impeller. It works fine, though I do notice that at very low rpms the engine temp rises a bit -- but now I also have a valve on the bypass hose, so if I need to I can direct more water through the cooling jacket.

She's running great right now.

[Qben]

Which shaft do you need? I have one that I just (last week) got from MMI for a Oberdorfer 202-M3/M7 pump rebuild. I was going to return it because I found (and purchased) a brand new pump for $100 on ebay (the same cost as the rebuild parts). Since I was going to pay shipping back to him anyway, I could ship it to you instead if you want and you wouldn't have to pay shipping.

Qben Oliver

[Baltimore Sailor]

Thanks, but that's low on my list of things to do right now, so go ahead and send it back to Don for a refund. I've got other stuff I want to take care of first.

[fixxxer0]

just put a new water pump in beginning of last season... planning on changing it next season depending how much use it gets this year.


i think it helps to take the impeller out of the pump over the winter so it doesnt get stuck in a certain shape (but im too lazy to do this anyway).

[jacques debauche]

Impeller replacement

We replace the impeller every two years simply because the things get tired. However, having a boat in which the water pump can actually be seen, and even worked on from a comfortable chair, and having one of Don's wonderful quick removal pump covers, we check the impeller every spring just to make sure it hasn't received mechanical damage. In our previous boat, getting to the water pump was a spelunking expedition, so we were not so conscientious. We paid for that with impeller failures, about every three years.

Pulling the impeller when the boat comes out of the water to avaoid having it take a set sounds like a good idea. Now if someone can just remind me to put it back in - - - .

[hanleyclifford]

spelunking?

Jacques - Francais, Deutsch, Quebecois?

[jacques debauche]

Spelunking

Spelunking: The hobby or practice of exploring caves (English)

[hanleyclifford]

English lesson

Jacques - I got it. Spelunking, from the Latin "spelunka" meaning cave. I stand corrected (again).

[jacques debauche]

MMO treatment of impellers

Since reading about it several days ago, I have been troubled by the implications of soaking water pump impellers in MMO before installation. Presumably the intention is to make them more flexible, and that's what bothers me. In a flexible vane pump such as the Oberdorfer (and the Moyer Improved) the vanes have to be flexible to accommodate the different pump chamber radii in the inlet area (long) and the outlet area (short). However, if the vanes are too flexible, they will bend backward more than intended as they approach the outlet port (as the pressure in the fluid increases) and allow fluid to flow backward toward the inlet port. This has the net effect of decreasing the pump capacity (GPM) for a given rotational speed (rpm).

Presumably the designers of the pump gave some thought to the appropriate flexibility of the vanes to achieve the right balance between effectiveness and durability. By making the vanes more flexible, are we upsetting this balance?

[hanleyclifford]

oil on impeller

Jacques - I share your concern about the practice of soaking impellers in ANY sort of oil. Some impeller materials can actually be chemically atacked by petroleum products, a possibility we must take into account given the unknown origin of some of the stock.

[Dromo]

soaking impellers

I use two impellers..one is installed in the pump and the other is soaking in brake fluid in a small glass jar. I keep swapping them out in the beginning of each season. I think doing this should make them last indefinitely. I soaked an impeller, that was in a used pump that I bought off E-Bay, for about three months and it came back to life, even the bent fins went back to their original shape.... looked like new!! As far as the vans being too flexible? I think that the centrifugal force on the impeller itself should counter any negative effect on the pump efficiency. My understanding is that brake fluid is formulated in such a way that it helps to keep all the soft rubber parts in the braking system from drying out and cracking i.e. boots on brake cylinders and calipers, inside master cylinder.
Just my two cents worth, to each their own.
Cheers Rick

[sastanley]

brake fluid????

Dromo, why brake fluid? That stuff is really caustic from what I understand..why not something to keep the petroleum in the impeller that isn't so bad like ATF or even motor oil? I read your comments about brake fluid, but it is still an honest question..not beating up on you..

[ArtJ]

I wonder what the shelf life is for unused impellers before they become brittle?
I usually keep a couple of spare impellers on board and swap them out originally
every year, but after speaking to Don Moyer do it every other year. This means
that the stored impellers could be several years old before being used.

The other thing I do is during the winter at least bi weekly, I remove the
plugs squirt some mmo at the pistons and valves, turn the engine over]
by hand. This also keeps impellers from becoming permanently deformed.]

But again, i wonder how to gauge shelf life?

Regards

Art

[JOHN COOKSON]

I don't know if it does any good but I store my spare impellers in a airtight bag. The bag also makes them easier to find. The last one I installed had been stored this way for 6 years and was still servicable.

TRUE GRIT

[jeffgerritsen]

Hum....,
I've only owned the boat for about two years, and a new raw water pump was installed by PO when I purchased the boat.... So I guess it's time to replace the impeller!