As I always told my students, there are no bad questions or dumb questions or insulting questions. Just questions. So I appreciate everyone trying to help. It is why I love this community. Knowing you are all out there gives me confidence to tackle problems that don't have YouTube videos to walk me through.
To sum from some earlier questions: 1. I verified that the pump shaft is turning. 2. I am pretty sure the impeller is turning because the pump housing got very hot very quickly from a brief test engine run with no water moving. 3. I can find no obstructions to flow from the seacock to the pump. You comment actually makes me wonder if I have been working under some bad assumptions in doing diagnostics. I had presumed that water would flow rapidly into the raw water pump due to water pressure and the pump would move it along. But as you pointed out, the pump is quite a bit higher than the entry point, so maybe the pressure is fairly neutral there. If I open the seacock, with the cover off the pump, should I see water flowing into the pump? Does the pump simply move water that is already there due to pressure flow, or does the pump actually draw the water into the seacock/strainer by sucking it in? If the latter, then many of my tests have been beside the point and nothing is blocking the flow of water into the boat. It is more that the pump is not drawing the water in, which gets back to the air leak issues mentioned. 1. If it is air leaks in the pump seal, I would propose to use a gasket sealant line Form A Gasket in addition to the o ring to seal the cover? Any reason that is a bad idea? 2. I asked earlier, but is there possibly a pump priming issue? I have never heard of someone having to do anything to prime there raw water pump. I did read an online engine thread where people had this problem with a particular engine, but simply revving the engine got the pump primed and pulling water. Dave David Knecht S/V Aries 1990 C&C 34+ New London, CT  > On Jun 5, 2025, at 4:58 PM, rickbrass--- via CnC-List <cnc-list@cnc-list.com> > wrote: > > 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 > <mailto:cnc-list@cnc-list.com>> > Sent: Thursday, June 5, 2025 4:42 PM > To: John Irvin <skis...@outlook.com <mailto:skis...@outlook.com>> > Cc: Stus-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>>; David > Knecht <davidakne...@gmail.com <mailto: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. Please help by making a small contribution using >>>>>>> PayPal at: >>>>>>> https://urldefense.com/v3/__https://www.paypal.com/paypalme/stumurray__;!!LIr3w8kk_Xxm!pZPXqf0N06PSxGS6nGO9KrBafHmmNbAHvV1qXeoJBQtWUzsqpX0o7OHRecZKK1B_ilJoRZ2G7haKXPI9iCONU2g$ >>>>>>> >>>>>>> <https://urldefense.com/v3/__https:/www.paypal.com/paypalme/stumurray__;!!LIr3w8kk_Xxm!pZPXqf0N06PSxGS6nGO9KrBafHmmNbAHvV1qXeoJBQtWUzsqpX0o7OHRecZKK1B_ilJoRZ2G7haKXPI9iCONU2g$> >>>>>>> All contributions are greatly appreciated. >>>>>> >>>>>> Your contributions help pay the fees associated with this list and help >>>>>> to keep it active. Please help by making a small contribution using >>>>>> PayPal at: https://www.paypal.com/paypalme/stumurray >>>>>> <https://urldefense.com/v3/__https:/www.paypal.com/paypalme/stumurray__;!!LIr3w8kk_Xxm!qDCB107FV545ldgV0tlZsQBNKnpSYz9z0E9zQPRdIsNRWQRwwuSzb6re2jDKQW-KijaHYMyaCaM47J4ZkqHtOaQ$> >>>>>> All contributions are greatly appreciated. >>>>> >>>>> Your contributions help pay the fees associated with this list and help >>>>> to keep it active. Please help by making a small contribution using >>>>> PayPal at: >>>>> https://urldefense.com/v3/__https://www.paypal.com/paypalme/stumurray__;!!LIr3w8kk_Xxm!qDCB107FV545ldgV0tlZsQBNKnpSYz9z0E9zQPRdIsNRWQRwwuSzb6re2jDKQW-KijaHYMyaCaM47J4ZkqHtOaQ$ >>>>> >>>>> <https://urldefense.com/v3/__https:/www.paypal.com/paypalme/stumurray__;!!LIr3w8kk_Xxm!qDCB107FV545ldgV0tlZsQBNKnpSYz9z0E9zQPRdIsNRWQRwwuSzb6re2jDKQW-KijaHYMyaCaM47J4ZkqHtOaQ$> >>>>> All contributions are greatly appreciated. >>>> >>>> Your contributions help pay the fees associated with this list and help to >>>> keep it active. Please help by making a small contribution using PayPal >>>> at: https://www.paypal.com/paypalme/stumurray All contributions are >>>> greatly appreciated. > Your contributions help pay the fees associated with this list and help to > keep it active. Please help by making a small contribution using PayPal at: > https://www.paypal.com/paypalme/stumurray All contributions are greatly > appreciated.
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