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Type of replacement waterpump

Discussion in 'Z3 Roadster & Coupé' started by pina4greg, Nov 1, 2014.

  1. pina4greg

    pina4greg Dedicated Member
    Australian Zeds

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    Just trying to get a sample of the types of water pump that have been replaced in the z3.
    i have found that there are the originals with plastic impellers, ones with composite impellers and then the metal ones.

    can you tell me your experiences regarding price and quality and improvement<
     
  2. GazHyde

    GazHyde The Gaz Monkey
    Staff Member Administrator Global Moderator British Zeds

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    When I changed my I bought a metal impeller version from my local motor factors, but that decision was purely on cost at the time. If I could have afforded it I would have probably gone with a Stewart pump on reputation.

    As for quality, it's been in there several thousand miles and hasn't broken yet!
     
  3. Cooper

    Cooper Zorg Guru (IV)
    Supporter Australian Zeds

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    There are quite a few posts on this. The consencious seems to be the Stewart but if you cant get that then get one with a metal impeller. Please excuse spelling mistakes i am on the Tab!

    There are a lot of dif experiences with some people changing out their plastic impeller pumps with no damage whatsoever! Others have had failures and wish they had a Stewart, and usually get one!

    Hope that helps.
     
  4. jonco

    jonco Zorg Guru (III)
    Supporter British Zeds The M44 Massive

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    Stewart's are good but expensive. I fitted a Meyle (metal impeller) - good quality and mid range price.
     
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  5. tower

    tower Zorg Legend
    British Zeds Scottish Zeds

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    have just finished renovating the cooling system ,water pump was a Kohle Schmidt (metal impeller) oem replacement from c3bmw
     
  6. vintage42

    vintage42 Dedicated Member
    American Zeds

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    Most Z3s were given solid composite plastic impellers, probably a good compromise of cost and light weight and durability.
    Metal impellers can be either solid or sheet. The solid metal Stewart or Geba impeller is a replacement upgrade, does not come apart, but their weight can shorten the life of the pump bearing.
    Here's a video showing a Graf pump with an impeller made of sheet metal that is spot-welded:

    View: https://www.youtube.com/watch?v=eeFUhg8PmDk

    They can come apart.
    http://www.m3forum.net/m3forum/showthread.php?t=338159
     
  7. oldcarman

    oldcarman Zorg Guru (V)
    Supporter Canadian Zeds The M44 Massive

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    Seems to me that the unevenness would put undue stress on those few spot welds and uneven pressure on the bearings, from the waterpump in the video. Kind of scary that all that fragmented metal could get circulating in the engine. JIM
     
  8. vintage42

    vintage42 Dedicated Member
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    At least it's in the cooling system, not the lubrication system.
     
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