Raw water pump cover - using the second side

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Nick F

Guru
Joined
Sep 2, 2020
Messages
598
Location
Canada
Vessel Name
Callisto
Vessel Make
1974 Grand Banks 42 Classic, Hull 433
I am getting to know my new (to me) 1976 boat. I am rebuilding the (Johnsen F5B) raw water impeller pump and the inside face of the cover is badly worn (see photo). Since the face of a new cover is just flat, it occurred to me that all I needed to do was to install the cover with the worn face to the outside. Not so easy! The manufacturer has stamped his (her) name etc. on the outside of the cover (see photo).

I thought about sanding the face smooth but it could be a lot of sanding and it is important that the surface be flat. Our friendly machinist at work helped me out and skimmed off 0.012"(twelve thousandths) - and I am set to go!! (see photo)

Nick
 

Attachments

  • Raw cover - worn.jpg
    Raw cover - worn.jpg
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  • Johnsen pump cover pic.PNG
    Johnsen pump cover pic.PNG
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  • Raw cover machined2.jpg
    Raw cover machined2.jpg
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I found mine flipped round by the PO, for no reason. It was using the engraved surface inside the pump with the impeller riding on it. Actually, it worked just fine like that. I only turned it back around because I am OCD.
 
I have flipped mine. Just polish off any burrs from markings with fine wet & dry.
 
Flat is the key , folks that travel should stop at any big glass store and see if they will trim a busted piece of 1/2 or thicker plate glass to a modest size and trim the edges.



Now any piece of emery cloth and some rubbing can refresh a true flat surface.
 
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