Noise after replacing impeller and fuel/water separator

rossbar86

Petty Officer 3rd Class
Joined
Apr 13, 2024
Messages
75
I just replaced the impeller and fuel/water separator today and now notice a sort of rhythmic "brushing" or "scraping" sound. Can anybody help identify this noise? Is it a belt issue?

View attachment IMG_3610.MOV
 
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MarineSp

Cadet
Joined
Apr 5, 2026
Messages
8
That rhythmic brushing sound is almost certainly the impeller itself. Most likely causes:

  • Impeller blades installed backwards (they need to curve in the direction of rotation)
  • One blade folded back during installation and scraping the housing
  • Housing cover not seated fully flat, causing slight contact
Pull the impeller cover back off and check the blade orientation first – it's a 5 minute fix if that's the issue. Also check that you got all fragments of the old impeller out; leftover pieces can cause exactly that sound.
 

rossbar86

Petty Officer 3rd Class
Joined
Apr 13, 2024
Messages
75
That rhythmic brushing sound is almost certainly the impeller itself. Most likely causes:

  • Impeller blades installed backwards (they need to curve in the direction of rotation)
  • One blade folded back during installation and scraping the housing
  • Housing cover not seated fully flat, causing slight contact
Pull the impeller cover back off and check the blade orientation first – it's a 5 minute fix if that's the issue. Also check that you got all fragments of the old impeller out; leftover pieces can cause exactly that sound.
Thanks! It was my first time replacing the impeller so very well may have foolishly installed it backwards...thanks! The previous impeller was well intact and didn't see any fragments in there but I'll take a look.
 

Horigan

Senior Chief Petty Officer
Joined
Jun 12, 2016
Messages
736
Impeller blades self-orient to proper direction, so you don't need to worry about which direction they go in, assuming you installed the correct impeller. As suggested, make sure you removed any old impeller pieces in the system. Put your hand on the pump while running to see if you can feel the noise. Otherwise, pull the impeller and see if there are any signs of unusual wear in the pump body.
 

rolmops

Vice Admiral
Joined
Feb 24, 2002
Messages
5,720
Impeller blades self-orient to proper direction, so you don't need to worry about which direction they go in, assuming you installed the correct impeller. As suggested, make sure you removed any old impeller pieces in the system. Put your hand on the pump while running to see if you can feel the noise. Otherwise, pull the impeller and see if there are any signs of unusual wear in the pump body.
Mmmm, interesting....
When inserting the impeller, use some form of lubrication (soap) and turn the impeller forward in the direction of rotation clockwise while inserting it. When properly installed, the tips of the fins should be bending backward when the propeller moves forward.
 
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rossbar86

Petty Officer 3rd Class
Joined
Apr 13, 2024
Messages
75
Okay, maybe it just needed to run a while b/c I let it go for 5-10 mins and everything seemed to sound just fine. I even used a stethoscope on the water pump, alternator and power steering pump and nothing sounded odd or the brushing / scraping sound wasn't even present
 
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