At the risk of stating the obvious and being insulting, be sure the end of the raw water inlet hose is well below the waterline level of the boat. If the open end is too high, you would probably see only limited flow due to the reduced or nonexistent pressure.
From: David Knecht via CnC-List <cnc-list@cnc-list.com> Sent: Thursday, June 5, 2025 4:42 PM To: John Irvin <skis...@outlook.com> Cc: Stus-List <cnc-list@cnc-list.com>; David Knecht <davidakne...@gmail.com> Subject: Stus-List Re: Water pump mystery Update. Diver confirmed nothing blocking thru hull. So with seacock open water flows strongly out of strainer with lid removed. But it dribbles slowly out of raw water pump inlet hose. The only thing in between is raw water strainer. Basket is clean. Not sure how to assess water flow through it but suppose i will have to remove it. Major inaccessible pita. Dave Sent from my iPhone On Jun 5, 2025, at 1:44 PM, John Irvin <skis...@outlook.com <mailto:skis...@outlook.com> > wrote: It’s more likely to suck air and not pump. Get Outlook for iOS <https://aka.ms/o0ukef> _____ From: David Knecht via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > Sent: Thursday, June 5, 2025 1:13:24 PM To: Stus-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > Cc: David Knecht <davidakne...@gmail.com <mailto:davidakne...@gmail.com> > Subject: Stus-List Re: Water pump mystery Fyi. I am on my mooring so some ideas aren’t practical. Dave Sent from my iPhone On Jun 5, 2025, at 1:09 PM, David Knecht <davidakne...@gmail.com <mailto:davidakne...@gmail.com> > wrote: Hi john. Wouldn’t the pump be leaking water if seal is bad? Dave Sent from my iPhone On Jun 5, 2025, at 12:49 PM, John Irvin via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: Impeller gasket must make a perfect seal. Get Outlook for iOS <https://aka.ms/o0ukef> _____ From: ALAN BERGEN via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > Sent: Thursday, June 5, 2025 12:46:37 PM To: Stus-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > Cc: ALAN BERGEN <trya...@alumni.usc.edu <mailto:trya...@alumni.usc.edu> > Subject: Stus-List Re: Water pump mystery Air might be getting in without water leaking. It happened to me once, and it took me a while to figure it out. Alan On Thu, Jun 5, 2025 at 9:00 AM David Knecht via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: Hi alan. Wont it leak water if seal is not tight? I have new gaskets on order but figured if it didn’t leak i was ok for now. Dave Sent from my iPhone On Jun 5, 2025, at 11:39 AM, ALAN BERGEN via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: If the cap on the raw water strainer doesn't have a tight seal, you won't get water pumping. Alan On Thu, Jun 5, 2025 at 8:31 AM David Knecht via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: Eliminated many possibilities yesterday. Pump shaft turning fine. Replaced impeller. Still not pumping water. Has anyone had a priming problem? My current hypothesis is that either the pump is not self priming or the seacock is partially plugged limiting flow. Water comes into raw water strainer with lid off but no idea if it is normal rate or not. Dave Sent from my iPhone On May 30, 2025, at 9:39 PM, Ronald Scott via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: Possibly the impeller connection to the sea water pump pulley became disconnected…resulting in the impeller not being turned to pump properly the sea water. This happened to me when I had installed both a new seawater pump and a new impeller. The guy doing the installation made the connection better between the impeller and the sea water pump pulley, and normal pumping of water resumed out the stern. He did say that the pulley was somewhat worn (where it connects with the impeller), and suggested I install a new pulley. Hope this helps! Ron Scott C&C 35 MK II (Rapid Transit) Drayden, MD Danville, Ky Sent from my iPhone On May 30, 2025, at 3:51 PM, ALAN BERGEN via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: Is the belt tight enough? Run the engine and see whether the pump is turning. If not, tighten the belt. If yes, remove the exit hose from the pump and see whether water comes out when the engine is running and the pump is turning. If no water comes out, change the impeller. Alan Bergen 35 Mk III Thirsty Rose City YC Portland, OR On Fri, May 30, 2025 at 12:34 PM David Knecht via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: I noticed today when i turned the engine on that i could not hear water coming out the transom port. Just air bubbles. Also the temp gauge read zero which i am guessing would happen with no water near sensor. Opened intake strainer cap and water comes in when seacock is opened. Took cover off sherwood water pump and looks normal inside. No missing vanes. Opened seacock and water came out of hose from the intake. I’m stuck. Any ideas? C&c 34+ Universal m4-30 Thanks. Your contributions help pay the fees associated with this list and help to keep it active. 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