New impeller, no water flow

[maxgm4]

After recently pulling the head on my 1960 10hp Sportwin to install a thread-insert into a stripped spark plug hole, I decided to replace the impeller. The water didn't seem to be flowing out of the motor in as much volume as I was used to.

I purchased the proper impeller kit and consulted the manual to install it. After getting it all back together and cranking the motor, I got no water flow out of the motor, and turned it off. Repeated attempts yielded the same result. I'm sure that the water tube is connected to the water pump housing, and I'm sure the impeller is sitting on the key pin and spinning.

The original water pump worked after I pulled the head, so I don't think i clogged any of the water passages in that process. I'd like to narrow down the possibilities before I drain the lower unit and fight to remove it again. What could be wrong?

 

[samo_ott]

Re: New impeller, no water flow

It pretty much has to be one of what you checked. The tube must be in the housing and the pin must be in the impeller. There's not really much else to go wrong in there. Unless maybe you removed the plate below the impeller and put it back on the wrong way? I think there's only 1 way to install it though.

If you want to test the LU, I remove it and put it in a pail of water and use my 330 rpm 1/2" drill and spin it. When I do this the water usually shoots about 8-10" up out of the tube... That solves the LU part, if that works then it' a tube connection issues or a blockage in the powerhead which it should not be your case...

 

[ezeke]

Re: New impeller, no water flow

A couple of other small things:

One is that the air bleed hole in the top of the impeller housing needs to be clear to vent the air so that the incoming water can displace it. It's small, but easier to see from the impeller side;

Another is that it fairly easy to get the rubber sleeve pushed in by the water tube in such a way as to block the flow;

Lastly, to easily prime, the pump needs to be covered with water when you run it in a bucket.

 

[R.Johnson]

Re: New impeller, no water flow

The impellor plate, and pump housing are probably long overdo for replacement, they wear out too.

 

[samo_ott]

Re: New impeller, no water flow

Probably true but it shouldn't account for no flow...

 

[maxgm4]

Re: New impeller, no water flow

I forgot to mention another observation:

Water is coming out of two small holes on either side of the lower unit towards the transom side when the motor runs. I don't know what they are, but they seem like drains for when water gets in the LU outside of the impeller housing. This clues me into thinking that water is being pumped, but isn't making it up the water tube. Does this narrow it down at all?

I'm leaning towards that rubber sleeve interrupting flow through the water tube.

 

[wilde1j]

Re: New impeller, no water flow

Probably true but it shouldn't account for no flow...

Not so ... if the housing and/or wear plate are scored, it won't pump, especially at low RPM, since the pump is a PD pump at those speeds.

 

[samo_ott]

Re: New impeller, no water flow

But it worked prior to impeller replacement. Thus the housing must be in a good enough condition to work.

And yes, water coming out the lil holes means it's pumping somewhat. But they should be under water... Do you have the LU low enough in the bucket to test? The water pump must be lower than the water level to work.

 

[maxgm4]

Re: New impeller, no water flow

Its possible that the bucket isn't big enough to put the pump below the water level. I assumed that as long as the water pickup is below the level, it would be fine. I'll try to find a bigger container or take it down to the boat ramp...

 

[samo_ott]

Re: New impeller, no water flow

That's probably the issue. The water pump needs to be submerged. It does not suck up well. Let us know.

 

[R.Johnson]

Re: New impeller, no water flow

Put sealer under a new plate as recommended, replace the housing, and I'll bet it work's like it's supposed to.

 

[maxgm4]

Re: New impeller, no water flow

After cooling down from all the frustration, I pulled the LU off again. The rubber sleeve was all jammed down into the tube on the pump housing blocking the flow. When I mated up the LU with the motor I must have forced the sleeve out of its seat and down the tube. I pulled the sleeve out, lubed it up, and put it back together again this time taking care not to force it.

I took it around the corner to the lake and it worked! Although the water seemed to be coming out hotter than I remember, the volume seemed back up to normal.

Thanks for the help.

 

[R.Johnson]

Re: New impeller, no water flow

That engine should have a thermostat, how old do you think that, and the pump might be. That is an aluminum pump housing. In river water, they don't last to long.