Raw water impeller

[Shaneesprit]

Hi question on the water pump">raw water pump impellers.
Beta Marine impeller is 6 bladed, but my pump has a 10 blade Jabsco 18653-0111 impeller fitted.

Tried to replace it with a genuine Beta 6 fin model, and it doesn’t pump water?

Only need answers from someone who has experienced doing this, I will be quite capable of sorting it out, just thought someone must of done this already.

So checked everything else other than running the pump without the cover or replacing the old one.
If I feed it any water or manually fill the filter it pumps fine.

Beta 25hp johnson pump and as far as I can tell all original.

[kmacdonald]

You said Jabsco impellor and Johnson pump. Try the correct impellor. Beta has used Jabsco and Johnson pumps. Depends on year.

[Shaneesprit]

Originally Posted by kmacdonald

You said Jabsco impellor and Johnson pump. Try the correct impellor. Beta has used Jabsco and Johnson pumps. Depends on year.

I know what I said.
That’s the problem, fitting the correct impeller appears to of stopped the pump working. Of course something else could of happened between using the boat, but unlikely as I started the engine only a couple of weeks ago. The chances of me not checking the water flow on that day are remote although I don’t remember checking it.

[Jim Cate]

If it is a Johnson pump there will be a part number on the cover. Armed with that, go to their website and find the pump model. The correct impeller part number and description will be there. Speculation based upon the engine is a waste of time, for substitutions may have been made from typical specs for t he engine.

Jim

[HeywoodJ]

Impellers in these pumps have to seal against the pump body and against the front cover and back wall. The body seal is pretty easy to see, the vanes get bent a bit (and more where they get to the cam), but the seal against the cover/back is also critical. You say it pumps once primed, but doesn't pump if not primed? That indicates that a little water creates a seal, but if there is only air in the pump it can bypass the pump action. That generally indicates the impeller is not sealed against the cover (or the back) of the pump. The gap is so small that once water gets in there it forms a seal, but air, being much less viscous does not.

Could be the 6-blade impeller is a slightly different height from the 10-blade, or could be a cover installation issue. One thing that can happen is a difference in thickness of the cover seal gasket. These are usually supplied along with the impeller, but if you are changing brands/models it is possible you get a thicker gasket than the previous one. Another option it that the previous gasket is still there and now there are two gaskets stacked on each other.

Yet another option is not enough contact with the cam (because of the wider spacing of the blades) but since it works wet I would guess that is less likely.

Those are the things I would look at, I can honestly say that I do NOT meet the "Only need answers from someone who has experienced doing this" qualification, I have zero experience changing from a 10-blade to a 6-blade impeller on a Beta engine.

[kmacdonald]

Heywood is correct. The seal between the impellor and front cover/back housing is usually the problem of not priming. Common on old worn pumps. You can buy a new front cover but when the pump housing is worn too much you need a new pump.

[Jim Cate]

Originally Posted by kmacdonald

Heywood is correct. The seal between the impellor and front cover/back housing is usually the problem of not priming. Common on old worn pumps. You can buy a new front cover but when the pump housing is worn too much you need a new pump.

We still don't know what marque pump this is. I agree that the seal between the sides of the impeller and the pump is critical for priming, and that this is a likely cause of the OP's problem. FWIW, some (maybe all) Johnson pumps have a replaceable wear plate at the back of the cavity. Replacement of this item and a new cover will restore that aspect of the pump to "as new". I recently did just that on one of my pumps.

Jim

[Shaneesprit]

I will have a look in a couple of weeks when I get back to the boat. Can probably turn the cover over, but main test will be to put the old impeller back in, see if that gets me back to the start. At least that gets me mobile. It’s been in there at least 5 years but I don’t motor that often.
Always have to arrive there with a plan as time is limited and the tide even more so. Actually have to check the tides to see if there is any water.

[kmacdonald]

Even if it won't dry prime, it will still work OK once primed and will probably stay primed. If the cover is symmetric it can be turned.

[FPNC]

The correct Beta impeller, Johnson impeller and Jabsco impeller are all interchangeable on most Beta engines.

While the impellers look a bit different, they will interchange. However, the face plate o-rings and/or gaskets will not interchange.

If your pump will not pump, you may have the wrong face plate cover or the cover plate or pump body may be too worn to make a proper seal on the impeller.

[MicHughV]

I usually smear some waterproof grease inside the main impeller housing as well as on the inside of the cover plate to help seal the impeller on the main housing as well as the cover plate. There is usually a wafer thin gasket there, but if this is broken or torn during removal, I slathered with grease around the edges, which seems to do the trick.

Had to flop the cover plate over one time as some some barnacle or something had worn a bit of a groove on the inside.. I took the paint off the outside, gave it a quick polish...some grease....and it worked fine..