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  #1   IP: 38.118.55.154
Old 08-24-2005, 01:34 PM
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Question Changing the impeller

We've had reliable service from our '74 Ericson 32's A4 over the now nearly nine seasons since we purchased the boat, but I hate to admit that I've never been able to change the water pump impeller. I've tried on two previous occasions with no success, and this is one of the reasons why I ordered your Service and Overhaul Manual last week. When I mentioned this to the very friendly fellow who took my order, he willingly walked me through what sounds like an easy and straightforward operation - "just take the cover off and pull". So armed with this professional knowledge I made another attempt over this past weekend and you may have guessed by now that the old impeller still remains in the pump housing. Thus I was looking forward to receiving the manual, convinced that somewhere in its pages there would be a clue - it arrived earlier this morning and sad to say, it provides even less information about this necessary operation than what I had already learned over the phone. Clearly our pump is a late model Oberdorfer and I understand the concept of the shaft and impeller coming out as a set - the problem is that I can't get enough of a grip on the impeller and even though I now realize that I can pull without damage, no amount of exertion has yet to free the shaft/impeller from the drive slot inside the engine. You must realize that attempting to change an impeller on this boat is a 'blind, one-handed operation', and that one hand is working backwards. I even made a 'puller' out of stiff wire in an attempt to reach through the blades to get a grip under the inner face of the impeller, but it's so tightly held against the housing that this had no effect. I also tried pulling on a blade with a needle nose pliers, but by that time I was afraid I'd end-up damaging the existing impeller to the point of disabling the boat. Obviously I gave up and put the cover back on. The engine is still pumping fine - it always has, but that impeller has probably been spinning much longer than we have had the boat. Do you have any ideas for a guy who's already purchased your book? I suppose we could just keep going and going, but at some point changing the impeller will become an emergency rather than what is now just perceived as an overlooked need. I can't believe that I'm the only person that has ever had a problem with this. Thanks in advance for anything you might suggest. Bill Dimmitt - Sioux City, IA
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  #2   IP: 38.118.55.154
Old 08-25-2005, 06:21 PM
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Don Moyer Don Moyer is offline
 
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Bill,

I'm not sure why the impeller is fighting you in this way, but I think I'd give up and remove the pump.

With the pump as old as you indicate that it is, the shaft may be a bit scoured, which would tend to make it a bit more difficult to remove. Once the pump is removed, you can simply push the shaft and impeller out of the housing quite easily.

Regards,

Don Moyer
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  #3   IP: 64.233.214.66
Old 06-16-2007, 08:30 PM
vain vain is offline
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Impeller retaining clip?

Hi Folks,

on the oberdorfer impeller -

Is there a retaining clip that must be removed prior to the impeller being able to be pulled from the shaft - or is it just pressed onto the shaft and held im place by the cover?

I also have never been able to pull my impeller out of the housing.


thanks

todd
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  #4   IP: 70.137.133.62
Old 06-18-2007, 02:32 AM
bayareadave bayareadave is offline
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keep at it

On my impeller, there was a clip that goes around the shaft that keeps the impeller on. I pulled the on the impeller blades and it came out with the shaft - no problem. To the original poster: I'd keep up with it until you get it replaced. The impeller on my powerboat failed and it was only 2 years old. I had to float on the current and then start up for short periods of time for steering / docking. Depending on how it fails, you may not know that water flow is reduced - resulting in melting some components of your exhaust (possibly causing fire), or damaging your engine.
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  #5   IP: 38.118.52.41
Old 06-18-2007, 11:13 AM
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Todd,

If you have an Oberdorfer 202M series pump, there is a small snap ring that holds the impeller on the shaft (product number CSOB_05_66 in our online catalog at moyermarine.com). You'll find a snap ring pliers in the Specialty Tools section of the catalog to assist in removing and reinstalling the snap ring. There is no reason that you should not be able to pull the impeller and shaft out of the pump other than possibly wear on the shaft.

Don
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  #6   IP: 216.114.167.162
Old 06-28-2007, 10:37 AM
Keymastr Keymastr is offline
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Red face take the retain clip off

I just OH my Oberdorfer pump and you have to take the retain clip off to change the impeller. Use a fresh gasket when assembling DON’T use the old one IT WILL LEAK.
Remember to put the drain plug back in the bottom of the pump. Trust me it fills your billage up in less than 5 minutes if you don’t. A dumb mistake on my part. That took all day to find. Get yourself a long extension bolt for the bottom bolt ,you won’t regret it.

Uwe
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  #7   IP: 38.102.24.196
Old 01-03-2009, 01:59 PM
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Fred,

According to Oberdorfer, the snap ring is all about keeping the shaft from moving freely within its limits of travel which would be from where its shoulder contacts the hub of the impeller to the roll pin in the center of the accessory drive gear (I estimate this distance to be approximately 1/4"). The impeller itself is securely contained within the confines of the impeller chamber itself.

My understanding is that design engineers feel a bit clumsy over allowing a shaft to "float" freely within an assembly. As a practical matter, I don't think anything bad will happen if the snap ring is eliminated as long as the pump is installed. The designer's worst fear is probably over the small likelihood that upon removing the pump from the engine, the shaft could try to stay in the accessory drive and end up falling into the bilge.

In designing the MMI flange pump, we did eliminate the snap ring because the shaft is held securely within the two ball bearings.

Don
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  #8   IP: 69.118.236.222
Old 01-04-2009, 05:42 AM
tenders tenders is offline
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I would also think that permitting a small amount of fore-and-aft wobble in the shaft could wear out the pump seals more quickly. I do know that pulling the shaft in and out of the pump too many times runs the risk of wearing out the seals!
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  #9   IP: 68.202.194.147
Old 12-03-2009, 02:43 PM
dvdcnl dvdcnl is offline
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impeller failure

Several years ago while motoring down the ditch, the A4 got hot. On investigating, the fresh water pump impeller rubber had separated from the brass which continued to turn with the shaft but the rubber quit turning. The impeller rubber was still in good shape; no cracks or broken fins.

Would this be caused by the antifreeze acting on the glue holding the two together?

Fortunately there was enough hose on board to hook the salt water pump to the engine and we continued to Beaufort where we obtained another impeller, flushed the engine with fresh water and refilled the cooling system with antifreeze.
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