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Water pump internals

Discussion in '308/328' started by topley, Aug 27, 2025.

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  1. topley

    topley Karting

    May 10, 2022
    92
    Los Angeles
    Full Name:
    Jay Barton
    #1 topley, Aug 27, 2025
    Trying to identify what I should have. This came out of my 81GTSi that I have been driving for 3.5 years. The weep hole had been siliconed shut many years ago by the looks of it. Not a surprise that by the time it started leaking it was crazy shot… So obviously it’s a large bearing pump but with 3 bearings. There was no spacer ring between the c-clip and inner most bearing and no spacer tube between that and the outer bearing. I’ve been searching and not seen exactly this… was it bastardized? And if so what should it have? Seems rebuildable if I use the original style seal?
    Thanks
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  2. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,290
    Black Forest Germany
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    Martin N.
    #2 Martin308GTB, Aug 28, 2025
    Last edited: Aug 28, 2025
    Yes! Rather! Maybe you can convert from the late two-piece-seal to the one and only reliable one-piece-seal.

    Can you show another picture with the back of the impeller?
    The "washer" between circlip and and inner bearing actually is a leaf spring washer. The spacer between inner and outer bearing is a simple part everyone with a lathe can make in ten minutes.(ID 15mm, OD 20mm, L=36mm

    Best
    Martin
     
  3. topley

    topley Karting

    May 10, 2022
    92
    Los Angeles
    Full Name:
    Jay Barton
    #3 topley, Aug 28, 2025
  4. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,290
    Black Forest Germany
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    Martin N.
    #4 Martin308GTB, Aug 29, 2025
    Last edited: Aug 29, 2025
    It's unnecessary, because with the big bearings pumps the seal was the problem, not the bearings. And a leaking seal with a clogged weep hole destroys the bearings. No matter how many.
    But when someone insists on a third bearing, what makes the whole situation statically overdetermined btw, you even need two spacers, 11.5mm long each. See my CAD screenshot. Without spacers it is a complete hack job and I wonder, how the pulley can be fastened tightly. Without spacer(s) between the inner bearing races you would simply push in the outer bearing while tightening the pulley nut. In the end the pulley would collide with the housing. Sorry, but someone in the past was completely unaware about what he was doing with your pump.

    See also my last posts of this thread on page 4 for what you need for a rebuild.

    https://www.ferrarichat.com/forum/threads/water-pump-rebuild.362611/page-4

    Three bearings draft with inner race spacers:

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    or like this. But then i would rather look, whether there's a two-row bearing in the needed ID and OD and adjust the spacer's length accordingly:

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    Best from Germany
    Martin
     
    ZikZak likes this.
  5. topley

    topley Karting

    May 10, 2022
    92
    Los Angeles
    Full Name:
    Jay Barton
    #5 topley, Aug 29, 2025
    Thanks Martin, this makes a lot of sense. I’m amazed as that water pump lasted for a long time like that even though it was probably failing for years.
     
  6. topley

    topley Karting

    May 10, 2022
    92
    Los Angeles
    Full Name:
    Jay Barton
    #6 topley, Sep 27, 2025 at 1:53 PM
    @Martin308GTB
    Ok. So I didn’t have a spacer nor the leaf spring washer and found a used water pump for a good price I thought I might be able to steal from. It did and I have these… but I am a little confused about this pump. It’s a big bearing pump but had the earlier impeller shaft and the machining for the seal is very different. Did not come with an impeller and I assume the impeller is different for this style? Or? Just curious if this is another water pump that’s been monkeyed with or there was some worth to this combination compared to my previous pump.
    Thanks
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  7. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,290
    Black Forest Germany
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    Martin N.
    #7 Martin308GTB, Sep 28, 2025 at 2:54 AM
    Hi Jay,
    you are correct. This design needs a different impeller. It's the perfectly original, earliest big bearing design with the earliest two piece seal (and the least reliable). Did I already mention my thread from 2011, when I have shown my design modifications from old two piece seal to modern one-piece seal?

    https://www.ferrarichat.com/forum/threads/another-waterpump-conversion-thread-old-seal-modern-seal.514339/

    Don't know why, but the embedded link to my oldest thread from 2011 is broken. So here's the direct route:

    https://www.ferrarichat.com/forum/threads/308-w-pump-altering-design-old-to-new.328021/#post-140610396

    First of all; don't worry about the spacer between the two bearings. This impeller/seal design changes don't affect the bearing design. The spacer of all "big bearing pumps" is identical in length and inner/outer diameter.

    These are the two impeller versions:
    Earliest two-piece seal design with the thicker seal portion (19mm? out of memory) on the shaft: Like for the one you show above:

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    Later design for the later two-piece seals and the latest one-piece seal (seal portion on the shaft out of memory 16mm(?)
    Like your original pump:

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    The pump you purchased is the perfect version for the conversion I describe in my old thread from 2011. Since you have to cut down the diameter on the shaft for the seal from 19mm to 16mm anyway (dimensions out of memory, you should compare both shafts for confirmation), the condition of the shaft doesn't matter at all.

    Best from Germany
    Martin
     
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