It appears as if there is a groove about 1/2" wide x 1/8" deep worn into the bowl possibly from where the impeller rides or is this normal, any advice in this is greatly appreciated.

I am also in the process of overhauling a WJ that had a low growl noise (noticeable at low rpm).  However I found the front bearing to be a little rough. 

If you don't feel that the problem is in the pump I would recommend checking the coupler (u-joints) for problems.  Also check your engine mounts and alternator mounts for looseness that could be allowing things to move around. 

Guys, is this sound while running on the trailer? I have noticed the WJ likes to growl some, not a lot but some with no water running through it. Dont run your jets to long on the trailer and never at a high RPM. 

Kinda hard to tell if the u-joints are going bad in the boat unless they're REALLY shot.........Just an idea here that might help.

When I pulled Moo's engine, in playing around with the driveline on a surface plate for other reasons dealing with the new MoMo, I noticed it felt like flat spots on the needle bearings?

Haven't pulled it apart, since it's going to a new 1350 driveline anyway, but I expect that's exactly what I'll find in it when/if I pull it apart. Probably not enough deflection in the crankshaft/pump shaft drive angles caused it since it was all new 2 years ago, but I can easily see where these joints could cause a "growl" well before they are completely shot.  Probably growl the whole time, just can only hear it at low RPM.  I could never hear ANYTHING on Moo, with the open headers, solid cam, roller rockers, etc, the thing buzzed and growled anyway.......

Ray

I'm not sure if I can help. I would think the shaft is either bent or the bearing and bushing has a lot of play in it to let the impeller move around like that and touch the bowl. I have a Jacuzzi 12/WJ and mine has a low growl sound at idle sometimes. I disconnected the u joint from engine so I could feel for any roughness, play or noise and my shaft turns very smooth. I could not feel any play or movement in it. I now feel somewhat better about the bearing but I would like to know what this noise is. Did yours make some noise? I would think it would as the impeller touched and ground against the bowl. I would think that if everything feels smooth and the shaft has no movement or play in it, then sand or debris has ground between the moving parts and the bowl.

Can't really say if it made any growling or not being I have never ran it. Its the pump that came with the boat I bought and is a on going project at this stage and was'nt sure what it would take to get the pump operational, plus with funds being a little tight. I do have a complete YJ in good condition but really did not want to go backwards and install it. I may also add the WJ was completely taking apart and is needing some small parts here and there. I just need to look at the parts break down to see what is needed. Im just not sure if the bowl is ok to use due to the groove in it.