Water pump that won't pump

[Bob N]

Never made a difference before and (oops)

First, I was referring to the seawater pump on my FWC engine.

Now: I was following the same procedure I follow each spring for starting the engine before the engine is launched. The strainer body filled with water and there was water in the pump when I opened it up to see what was going on. There was just enough water on the ground below the boat to suggest that some small amount went through the exhaust system.

I'm thinking I will try opening up the strainer and inject some water with a squeeze bulb to see if some extra priming will help.

I'll also check to see if the impeller is thinner than the old one, as folks have suggested above. But the new one is one that I just bought from Don.

[grant.mckenzie]

If you are using rubber gasket might want to make sure that it is seated properly and nut jamming the impeller. Happened to me yesterday.

[Bob N]

Problem appears to be solved

I swapped out the new impeller for the old. The new one measured 1/64" undersize. The pump is now pumping like a champ. Of course, now I am worrying about the engine coolant pump, which I also put a new impeller in. I'll have to crawl down into the bilge to check that out if the engine runs hot after launching.

[sastanley]

Are Bob N & egmonster the same person?

Bob N/egmonster...

It would appear from this thread that you have two different accounts...please confirm you are the same person so we are satisfied that your issue is solved...

We've gone very far down the impeller rabbit-hole previously so we like to confirm things from time-to-time!

[Bob N]

2 accounts?

It's just plain old me--Bob N.

[Bob N]

Further reply to 2 accounts

Who/what is "egmonster?" I'm just "Bob N," always have been.

[ILikeRust]

This thread was started by someone with the user name "egmonster." Partway through the thread, Bob N said, "Hey, I have the same problem." Then a few posts later, Bob N reported "Hey, problem solved."

So for the casual thread-reader, it looked like egmonster suddenly started posting as Bob N partway through...

[ILikeRust]

It looks like egmonster hasn't checked in here since his last post upthread here.

[roadnsky]

It looks like egmonster hasn't checked in here since his last post upthread here.

I concur Doctor...

[prstack7]

success with new impeller

With the advice of the forum on this thread and others and the advice of
Don by email, I now understand the problem with new impellers in old pumps. The PO of my boat never changed the impeller. When I did, I experienced a lack of water flow. I switched back to old impeller and had great flow. I removed the cover plate and discovered deep grooves. I sanded down the plate, soaked the new impeller in MMO for 2+ days, reinstalled new impeller, and the system works great. I have a slight drip from the plate because I didn't sand completely flat, but it's very slight.

[tenders]

That little drip will drive you nuts and slowly rust your engine. I'd suggest fixing it, possibly with a little Permatex around the sealing surface.

I just bought the Moyer version of this pump and am reserving judgement until I've had a few seasons to try it out, but I think the original Oberdorfer pumps are a pretty weak link in the A4 system. I've been around a few A4s over 30 years and would guess that the pumps have been working at 100% to their design less than 30% of the time.

They're expensive, easily munged up and leak-prone between either the finicky seals or the finicky chamber plate, the seals are expensive and somewhat difficult to rebuild, the grease-cap-twisting regimen is barbaric and fraught with likelihood for failure, the impeller retaining clip is inconvenient, and this whole recent issue with the impeller sizing is just dumb to have to contend with.

There, I've said it.

I'm glad I don't have FWC and another one of these types of pumps to deal with.

[romantic comedy]

Let me post another opinion:

The original 1974 pump has worked since new, as far as I know. Yes I have rebuilt it a couple of times in the last 15 years. The rebuilds are very easy with no special tools required. Cheap too. I can do it aboard. I have another new pump as a spare. This year, I swapped out the original for the spare, because I know the original works fine.

I have FWC, that I made up myself. No Kit. I use the Oberdorfer 201M pump for the seawater. This pump has failed twice. By failed, I mean that the seal leaked and I had a stream pissing into the bilge. I recently had the 201M rebuilt by a shop. (the shop that Don recommends, it is near me). It cost a little over 200 dollars.

It seems that the mechanical seal on the 201M is not tolerant of sitting around for months of no use. Imagine that?

while I agree that the 201M which has "real" bearings, and not just bushings, may seem like a better pump, it has not been that way for me. It is all about reliability!!

The MMI pump looks wonderful, and I would love to have one. I think that Don uses a better seal for that pump, but I dont know.

I have two original type engine driven pumps, and two Oberdorfer 201M pumps. I think that is enough. I dont need any more ballast.