MD5A Water impeller not self-priming

[sailorman]

http://www.ittflowcontrol.com/files/artdoc4851.pdf

[pvb]

No raw water filter (that's a different issue, but the Saildrive has a grating and it's quite deep).

I think if you were to fit a raw water filter above the pump, your problem would disappear.

[Tranona]

I think if you were to fit a raw water filter above the pump, your problem would disappear.

Whilst a good idea to fit the strainer, not sure it will cure the current problem. As several others have noted, it is almost certainly a worn pump or incorrect impeller. If it won't prime as it is, no hope of it lifting water even higher above the waterline. Only benefit would be that is is easier to prime by pouring water in the strainer with the seacock closed - but that does not solve the basic problem.

[forelle541]

I have just had the same problem on a johnson 35 Pump, it was just eating impellers and not priming. It turned out to be the seals not seating on the shaft and letting air past, when pumping water the pressure pushed the seal against the shaft so no leaks not a dribble to give them away. New seals and it sucks water straight away.

[pvb]

Whilst a good idea to fit the strainer, not sure it will cure the current problem. As several others have noted, it is almost certainly a worn pump or incorrect impeller. If it won't prime as it is, no hope of it lifting water even higher above the waterline.

If it works once it's primed, a raw water filter will ensure there's water above it in the inlet pipe to prime it.