Raw water not sucking

[Tony1972]

Hi all. This shall have a few head's scratching.
I have changed both impellers on my boat and at the same time cleaned out the raw water strainers,
Put both back to gether primed both.
Won't draw water on either engine the marina fitter can't even get them going this has been going on for a month now. And he also said both engines have alot of back pressure. And the water in the strainers drains out. Any clues anyone.
Regards Tony.

[ItDepends]

Without a plumbing diagram it's hard to do anything other than wildly speculate.

But this we can say for sure: If your impellers are in good shape, you have a clog on the inlet, or the outlet, or both. Also possible you have a large air leak on the inlet side. Also possible you put the wrong impellers in.

If you changed the impellers, and THEN everything stopped working... the last option above becomes quite likely.

[Tsuru]

Tony,
I had the same problem after a raw water pump overhaul. Turned out the face of the pump was scored enough to prevent the pump from priming. The pump face damage happened slowly over time so the old impeller wore or abraded to the face of the pump. The new impeller was not worn to match the pump face so the pump would not prime.
I replaced the face plate and the pump is still working. Easy to check with a straight edge across the pump face plate. It didn’t take much.
Good luck,
Ray

[Tony1972]

One face has been machined the other inside the housing is a bit scored. I can now see an over look by me and also alot by the marina. Twin engine's both got the same problem. Ouch

[Tony1972]

Thank you very much for your reply looks like worn out impeller housings

[Tony1972]

Thanks Ray