Replace Water Pump????

I am working on preppin' up the boat and decided to replace the impeller, since I don't know the condition of it since I bought it. Boat ran great last season, but the pee-hole was not shooting out water at times, so that is why I am replacing the impeller and taking a look at the water pump. After dropping the lower unit and removing the pump this is what it looked like.







A few things I noticed and questions:

1. The Key (that attaches to the impeller and the shaft) was off and sitting on the bottom of the shaft housing. Probably why the pee-hole was not shooting out water like it should.

2. The impeller was in OK shape, but will get replaced.

3. The wear plates seem to be in decent shape. I ran my fingernail along the plate, and it did not catch on any of the grooves, but did feel very, very tiny bumps, almost barely noticeable. Is this a cause/condition to replace the water pump??

4. The gaskets probably should get replaced. If you look closely in the second picture, where the impeller sits into the housing, there is gasket missing from the housing, but some of it is still in place to the right.

5. The last picture is the outside of the housing. A little dirty, but seems fine.

Sooooo, should I just replace the whole water pump, or just buy some gaskets?? Motor is a 2000 50HP Mercury.

Have you determined why the key was not in the impeller? Since you plan to replace the impeller, it would probably work just fine with just replacing the gaskets and reusing the rest of the pump parts.

That said, if it were me I would go ahead and get a kit and replace everything while I had the lower unit off. 8)

Sounds logical Larry. I think I am just going to order a rebuild kit and go from there. Can't hurt. About the Key, I am not sure why it was off. it looks to be fine and no chipping. Thanks for taking a look. Just needed a 2nd opinion.

That impeller is toast. Once they take set like that they don't develop pressure when spinning fast. Only ware plates I'll ever replace are so thin I think they will get holes thru them. Throw an impeller in and move on. Save the housing and wear plate kits for those that are so thin and cut up that you think they will disintegrate. All you need is an impeller. Lube it with your favorite slick stuff so it does not melt when you break it in and never start an engine out of the water for even a second.

If I wasn't so lazy and just using the tablet I'd upload the pictures of mine. My impeller looked fine maybe a 32s wear, the wear plate had a few grooves in it and I thought it wouldn't matter. All I know is, I bought the kit and mine pumps perfect now....it was missing the bottom gasket as well. Unsure how your key would have fell out if it was installed right to begin with.

Stumpalump said:

Only ware plates I'll ever replace are so thin I think they will get holes thru them. Throw an impeller in and move on. Save the housing and wear plate kits for those that are so thin and cut up that you think they will disintegrate.

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Stump,

The wear plates seem fine and thick. There is no thinness to them at all. As I mentioned above, my fingernails are not grabbing onto any of the grooves. The gaskets on the other hand need and are going to get replaced with brand new ones. I know about using some grease into the housing before adding the impeller and then running water through it. Good advice to anybody.

Zum said:

Unsure how your key would have fell out if it was installed right to begin with.

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I am unsure either. I didn't run the motor very long at all, when the the pee-hole was not working. This was the first time I dropped the lower unit on the motor. Was working great last year, but not sure if the key was installed properly are not. I was glad I made the decision to drop the lower and take a look. I am going to make this a part of my preventive maintenance and prep work before the season begins.

Pappy said:

The grooves in the wear plate and cup appear deep enough to warrant replacement. Keep in mind that the impeller blades are not properly sealed with these grooves and will not develop expected pressure and volume. Start fresh and don't look back!

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How deep is deep? I ran my fingernail along them and they didn't catch. The wear plate feels smooth. Would some marine grease help fill in those very very fine grooves? The replacement kits for my motor run about $80-100 from what I think is the correct part #. Starting fresh and not looking back seems like the best alternative, but if I don't need a new housing, then I can save some cash.

Pappy said:

Okay lets give it another approach. Grooves kill the proper sealing of the water pump. If your fingernail feels a groove and kind of drops down into it, even a little bit, it is time to replace due to the amount of addition wear it will accumulate for the next ??? long.
The grooves in the wear plate and cup allow water to escape to the following blade, every blade, every revolution. This pump already shows wear and you will be putting it together with an impeller for another what....3 years or more? That is 3 additional years plus the new impeller will take a set.
Point is not to save pennies (so to speak) and risk dollars (powerhead damage). It's apart. Do it once and do it right for peace of mind and good protection.

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Good argument Pappy. I will take your advice and just replace the whole dang thing. Better than a powerhead replacement for a simple water pump replacement. I was taking another look at it and deemed the housing to worn to just reuse again. Plus its probably as old as the motor itself. Thanks for the advice and steering me into a logical and smart decision.

For what it is worth, in a long life, filled with many questions...

I trust Pappy and his expert, professional, advice.

He does this for a living, and for his interest in resurrecting old boats and engines.


(We're very, very, lucky to have him here.)