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Changing Gen 5 raw water impeller

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Changing Gen 5 raw water impeller

Old 11-24-2021, 09:22 AM
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Default Changing Gen 5 raw water impeller

I have been advised that I have a Gen 5 raw water pump. (see below)
It says Hardin Marine on the side of the metal housing but also has the black "plastic" impeller housing.
I am trying to do an "annual" impeller change.
I am concerned about the complexity of removing the pump (and associated fuel pump connection).
Can anyone direct me to a DIY instruction/exploded detail view of how this comes apart/goes together?
Any lessons learned will be much appreciated.
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Old 11-24-2021, 01:42 PM
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make sure you have a water shutoff valve inf you’re doing it on water…
Not a gen 5 but should be similar.

https://www.youtube.com/watch?v=_xsPh9hm-Mg

https://www.youtube.com/watch?v=rOrlvEypvBM


here’s a little more detail on the impeller itself… only thing is I would NOT use wd40 on rubber. It makes it swell. I’d use a real marine grease.

good luck! I have a Johnson pump it’s mounted to crank pulley and just as much of a chore to do.
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Old 11-24-2021, 04:59 PM
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You should change impellers in the Spring so that the new one does not sit in one position all winter.
You have a Hardin pump with a Merc impeller/housing kit.
BTW, I only change impellers about 3 years.

Last edited by Griff; 11-24-2021 at 05:01 PM.
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Old 11-24-2021, 05:26 PM
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My Factory Service Manual states every 3 years for a raw water impeller. That's my plan.
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Old 11-24-2021, 06:37 PM
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Originally Posted by Xcomunic8d View Post
make sure you have a water shutoff valve inf you’re doing it on water…
That is great/smart advise...I'll do it in the lift or on the trailer (but I also have a shutoff valve in the system)
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Old 11-24-2021, 06:50 PM
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Originally Posted by Griff View Post
You should change impellers in the Spring so that the new one does not sit in one position all winter.
You have a Hardin pump with a Merc impeller/housing kit.
BTW, I only change impellers about 3 years.
How does that fuel pump interface with the raw water pump...is it complicated/semsitive?
Good advise (Spring, 3 years)...I had some higher than normal temps (180F vs 140-150F...140F thermostat) on my port engine during an extended idle/no wake time the last time I recovered the boat at the ramp. I figured that my first step would be to do the impellers (and compare the starboard and port). The motors were built 3.5 years ago about 75 total hours and no indication of impellers ever being changed.
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Old 11-24-2021, 06:51 PM
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Originally Posted by SabrToothSqrl View Post
My Factory Service Manual states every 3 years for a raw water impeller. That's my plan.
I will look for this Service Manual on line.
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Old 11-24-2021, 11:23 PM
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Originally Posted by F14A water jet View Post
How does that fuel pump interface with the raw water pump...is it complicated/semsitive?
Good advise (Spring, 3 years)...I had some higher than normal temps (180F vs 140-150F...140F thermostat) on my port engine during an extended idle/no wake time the last time I recovered the boat at the ramp. I figured that my first step would be to do the impellers (and compare the starboard and port). The motors were built 3.5 years ago about 75 total hours and no indication of impellers ever being changed.
The way I did it on my 525SC was to disconnect the fuel line at the fuel pump and then I would remove the entire bracket with the seapump/fuel pump attached and do all my maintenance on a bench.
The seapump/fuel pump has gear lube in it (Merc drive gear lube). The allen head plug is where you fill and drain it. Being a Hardin pump, there may be a plug on the underside to drain the lube.
The lube gets somewhat fuel diluted. I used to change the lube in mine every year. I just sucked it out with a 30cc syringe with some tubing attached and that would get much of it out. When I changed impellers, I would just tip it to get all the lube out. Like I said though, you may have another drain plug on the bottom.
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