Water pump has me stumped

[GatorMike]

I replaced my impeller a couple of months ago. Everything worked fine for several weekends. The other day I started the boat on the muffs and noticed a weak flow out the teltale for a while then it would start spitting and the flow was very light, then I would get a weak solid flow for a while. The heads felt like they were a bit hotter than they should have been so I shut her down and pulled the lower unit.

I disassembled the water pump and everything looked good. I put the Lower unit back together and installed it and got a very strong flow out of the teltale this time. I thought I had the problem fixed.

This morning I went out and started the boat on the muffs and was getting very little water to the powerhead. It was just spiting a every now and then from the teltale. So I filled a garbage can with water and lowered the motor into it and started it. This time I got no water at all through the teltale.

This has me stumped, does anybody have any idea what may be going on here? I can't imagine the impeller could be spinning on the shaft with the nylon wedge snuggly in place.
The water intake doesn't apear to be blocked but I really don't know much about these things.

Oh also while I had the LU off I hooked the hose directly to the water tube and got good flow through the powerhead so I would think the problem is from the water tube down.

 

[Joe Reeves]

Re: Water pump has me stumped

The engine is what?

Have you cleaned the water telltale pan outlet fitting, the fitting at the powerhead, and the connecting hose? Many times it's just a piece of loose debris, floating around, clogging the outlet area.

On a flushette, a high hp engine demands that the hose be on full blast.

In a barrel, the water level must be a couple inches above the water pump.

 

[GatorMike]

Re: Water pump has me stumped

Yeah Joe I did clean the telltale outlet I know it doesn't take much more than a grain of sand to clog that outlet.

It is a 98 115 Johnson crossflow. The lower unit is much older than 98 but they are compatible, I have had them mated up for years and things have worked fine. Let me ask you a couple of questions here Joe. 1. I have the lower unit off now, when I posted I went out and took the LU off, anyway on the shelf where the water pump sits there is a bunch of caked on sand, might that be a clue? 2. I just pulled the chrome plate off that sits under the water pump. The gasket on the bottom of that plate has a slightly different shape as the plate and it looks like there might not be a good seal there. Would there be enough pressure loss at that gasket to cause this problem?

 

[wilde1j]

Re: Water pump has me stumped

What looks like sand is often salt, if you run in saltwater.

The pump housing must be well sealed to the wear plate, or it won't pump very well.

What's the top of the wear plate and pump housing/liner look like? Any scoring?

 

[GatorMike]

Re: Water pump has me stumped

Slight scoring on the plate none on the pump housing. I just put it all back together with new gaskets and seals. Going to put the lower unit back on and give it a try.

 

[GatorMike]

Re: Water pump has me stumped

UPDATE...Put it all back together and still got terrible water flow. I figured I maybe there was something wrong with that new impeller so I went down to the local dealer to get another one, figured I'd replace all the seals and grommets while I was at it. The parts lady added up all my parts and she said for $20 more I could buy a complete water pump. So I went ahead and bought a new one. When I got home and compaired the new pump with the old one several of the components were badly worn and some of the old seals and o-rings were stiff.

I put the new pump together and installed it. Damn I am getting good water flow now. I guess it isn't enough to change the impeller every year or two. Eventually the pump wears out.

 

[wilde1j]

Re: Water pump has me stumped

Most DIYers don't do enough pumps to know what's reusable and what's not. The safest course is always to replace the whole pump. Glad you got it working.

 

[wilde1j]

Re: Water pump has me stumped

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