impeller won't turn

[FULL-THROTTLE]

98 challenger twin 787's, r/side engine starts but impeller does not turn, I can turn the drive shaft by hand and the impeller turns with it??????

Whats up with this???

 

[1970_mgb]

Are you turning the drive shaft by turning the flywheel or by the shaft? Could be as stripped spline on the drive shaft at the engine side. Its not too difficult to remove the pump then the drive shaft. It should be obvious at that point.

 

[FULL-THROTTLE]

Update

I am turning the drive shaft, the boat is not at my house so I cannot go out and see if it is turning the crank adapter/flywheel or not. Is there any way the ( I don't know the name of it ) crank adapter/flywheel could have backed off of the crank?

Thanks

 

[1970_mgb]

I do not think the drive shaft splines could back away from the flywheel/PTO with the pump in place. If you are turning impeller by the shaft you must have already removed the plastic protective cover over the Power take-off PTO. Try turning it by the flywheel. Even if the one of the splines are stripped I guess it might be possible to to turn the impeller by hand i.e . when there is very low tourqe applied.

 

[seadoodude1]

It's rare but I have seen posts where the hub in the impeller breaks loose and spins. Other possibilities is drive shaft splines stripped or PTO flywheel loose on the crank shaft. Some models have a coupler that may have broke, but I think those are older models. Did you suck up a rock or something that would have caused this problem?

 

[1970_mgb]

PTO flywheel loose on the crank shaft. ]

If this is the case the and the flywheel is loose, the flywheel and shaft should spin very easily since its not working against engine compression. Normally in turning the fly wheel you can feel the effort it takes to work against the compression of the engine.