priming the raw water system

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   I change the impeller on my 575's Volvo D3 every so often and more often than not, I have issues getting the raw water system to prime and pump thru.    One year the strainer lid was the culprit (the o-ring apparently was not seating).   Another it required me filling the hoses and strainer with water before cranking things up.   This year it took about 2 hours of fiddling to get things going after changing the impeller.   Its supposed to be self-priming....

I wonder if the height of the strainer above the waterline has something to do with the difficulty.   It *appears* to be about a foot or so above waterline but that's just a guess. 

Do others have this difficulty?   Do you have a sequence that works flawlessly every year?  If so,  please share.

Edited by Black Diamond - 01 May 2025 at 03:36

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Black Diamond Members Profile Send Private Message Find Members Posts Add to Buddy List Admiral Joined: 24 October 2015 Location: Newport, RI, US Status: Offline Points: 1275	Post Options Post Reply Quote Black Diamond Report Post Thanks(0) Quote Reply Topic: priming the raw water system Posted: 01 May 2025 at 03:36
	I change the impeller on my 575's Volvo D3 every so often and more often than not, I have issues getting the raw water system to prime and pump thru. One year the strainer lid was the culprit (the o-ring apparently was not seating). Another it required me filling the hoses and strainer with water before cranking things up. This year it took about 2 hours of fiddling to get things going after changing the impeller. Its supposed to be self-priming.... I wonder if the height of the strainer above the waterline has something to do with the difficulty. It appears to be about a foot or so above waterline but that's just a guess. Do others have this difficulty? Do you have a sequence that works flawlessly every year? If so, please share. Edited by Black Diamond - 01 May 2025 at 03:36
	Rick S/V Black Diamond Hanse 575 Build #192, Hull# 161 Newport, RI

Wayne's World Members Profile Send Private Message Find Members Posts Add to Buddy List Admiral Joined: 18 July 2012 Location: Cruising Status: Offline Points: 1434	Post Options Post Reply Quote Wayne's World Report Post Thanks(0) Quote Reply Posted: 01 May 2025 at 06:10
	I have had the odd problem with the generator raw water priming but not the Volvo. With the generator the cause may have been the impellor was not in good condition. But what I find works is to turn the sea water thru hull valve off. Remove the lid of the strainer and pour water into the strainer until the strainer and the downstream pipework is full of water. Replace the strainer lid. Open the sea water thru hull valve and start the engine.
	Wayne W Cruising, currently in the Pacific until the end of 2026.

kipwrite Members Profile Send Private Message Find Members Posts Add to Buddy List Commadore Joined: 14 October 2015 Location: New York Status: Offline Points: 495	Post Options Post Reply Quote kipwrite Report Post Thanks(0) Quote Reply Posted: 01 May 2025 at 07:49
	My technique is the same as Wayne's, with one exception: I keep the sea water intake closed until the moment the engine fires, started by an assistant - then I open the seacock. Not sure why my system isn't self priming but this method works every time.
	Kipwrite

Black Diamond Members Profile Send Private Message Find Members Posts Add to Buddy List Admiral Joined: 24 October 2015 Location: Newport, RI, US Status: Offline Points: 1275	Post Options Post Reply Quote Black Diamond Report Post Thanks(0) Quote Reply Posted: 01 May 2025 at 13:09
	Thanks... I think the complicating factor here is the strainer o-ring. If its not seated well (and mine seems fussy) then it seems to lose the vacuum necessary to self-prime. As such I have spares for the lid and the o-ring on board. On the generator Wayne, one of the first things that happened to ours was the impeller failing while on an extended cruise. I then found out that the placement was not (shall we say) the best for working on the required components. I remember asking Hanse about this during my factory tour (can you reorient it for me?) and they said it would require a new CE certification for the boat. I managed to get the job done at 90 degrees (all the things you need to work on face aft and your access is only from the sides) before noticing that the "hatch to the garage" probably gave you better access.
	Rick S/V Black Diamond Hanse 575 Build #192, Hull# 161 Newport, RI

Arcadia Members Profile Send Private Message Find Members Posts Add to Buddy List Admiral Joined: 27 November 2017 Location: Sag Harbor, USA Status: Offline Points: 1112	Post Options Post Reply Quote Arcadia Report Post Thanks(0) Quote Reply Posted: 03 May 2025 at 00:48
	Just some food for thought guys. I had the same problem with priming on the main engine which got progressively worse over the years. I discovered that the pump housing had considerable wear internally to the point that the intake and outlet holes had become oval shaped and the walls were paper thin. Even a new impeller could not create a good vacuum. This was at about 900 hrs. I found an after market replacement and it now pumps good as new.
	Leon / ARCADIA 2018 Hanse 588 Sag Harbor, NY

Arcadia Members Profile Send Private Message Find Members Posts Add to Buddy List Admiral Joined: 27 November 2017 Location: Sag Harbor, USA Status: Offline Points: 1112	Post Options Post Reply Quote Arcadia Report Post Thanks(0) Quote Reply Posted: 03 May 2025 at 00:59
	The JMP Marine number is JPR-VP0030DB. It’s available at a few online sellers. https://bigblueoceanmarine.com/jpr-vp0030db-jmp-marine-volvo-penta-replacement-engine-cooling-pump-replaces-volvo-penta-21379102/?srsltid=AfmBOoos-2ovX3oMa7LgkZE_PXn0rtsi27PCETFL17pPVSAuIRw-rDat
	Leon / ARCADIA 2018 Hanse 588 Sag Harbor, NY

Martin&Rene Members Profile Send Private Message Find Members Posts Add to Buddy List Vice Admiral Joined: 06 December 2009 Location: United Kingdom Status: Offline Points: 967	Post Options Post Reply Quote Martin&Rene Report Post Thanks(0) Quote Reply Posted: 03 May 2025 at 18:23
	As well as following Wayne's routine, I also take the pipe off the heat exchanger and fill that with water which will the pump then reconnect before starting the engine.
	Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland

Pzucchel Members Profile Send Private Message Find Members Posts Add to Buddy List Rear Admiral Joined: 13 March 2020 Location: floating Status: Offline Points: 659	Post Options Post Reply Quote Pzucchel Report Post Thanks(0) Quote Reply Posted: 07 May 2025 at 13:44
	interesting. i changed my impeller this winter and i didn't notice any issue at restart: the flow of water at the exhaust, to my eye, was even bigger than before....but it could just be an impression. Anyway, i never had the issue of priming it that you describe (i usually close the circuit before doing it, jut for safety...).
	Hanse588#55



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