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Rebuilding CAT/Cummins Sea Water Pumps

Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by dtfeld, Sep 22, 2020.

  1. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    Axiom 12 MFD
    Cat 3126 V-Drives
    Discussing with Bill (ZZ13) about rebuilding sea water pumps, specifically the Sherwood pumps on the CAT engines and the SMX pumps on Cummins. Anybody rebuilding? Are you sending out or doing it yourself, or just purchasing new pumps every couple of years.

    I replaced both my Sherwood 1732C pumps on my 3126's a while ago due to the water seal starting to leak on the port engine and wanting to zero out my impellers. I replaced the whole based on info saying the rebuild wasn't cost effective. New Pumps were $1100. I can purchase a minor rebuild kit (basically impellor and water seal) for $200/each so roughly 60% savings. One of the issues is access on the 3126. The oil gallery needs to be removed to access the impeller, so I'm considering building up a second set of pumps, as that just requires the removal of a couple hoses and 2 large bolts. Easier in my opinion on my boat.
  2. my3sons

    my3sons Well-Known Member GOLD Sponsor

    Feb 24, 2009
    NY (Lake Erie)
    2004 400DB, Onan 9 kw Gen, Highfield RIB,
    Cummins 6CTA
    I put smx pumps on my boat in 2015.
    I kept one Sherwood as a spare and take it with me when we travel. I have put 2000 hours on the smx pumps. I was a little shocked when Bill said he had one go bad. I was hoping for better longevity than that. I don’t know how long to expect them to last and if it is more a function of time in the water, age or hours. I’m hoping 15 years, the sherwoods were original and 11 years old.
    dtfeld and Blueone like this.
  3. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    Axiom 12 MFD
    Cat 3126 V-Drives
    Wow. 2000 hours??!! That a lot if time on a pump!
  4. kevin27

    kevin27 Member

    Aug 8, 2007
    Tarpon Springs,FL
    1989 3600 Convertible. 2017 Scout 175 sportfish.
    2002 Cummins 6BTA 330hp diesel straight shaft.
    I have SMX pumps on my Cummins. Got about 6 years and about 1000hrs on them. So far so good. I threw my Sherwood pumps in the metal recycling so no going back for me. The Sherwood are prone to shaft failure at the woodruff key slot and then the impeller doesn't turn. I would hate to overheat a 30k eng over a $750 pump. SMX pumps are spline shaft.
  5. ZZ13

    ZZ13 Well-Known Member

    Nov 25, 2009
    Lady's Island, SC
    2001 400 Sedan Bridge
    Cummins 450 Diamond
    I still haven't determined 100% that it is the pump. Could be one of the o rings at the elbow. My boat is on the hard for a few weeks and it's the port pump, so hard to debug. Once I get back in the water I'll remove it and put it on starboard engine for debug. Stay tuned. But, I did buy a new water seal for the pump just in case. If I need to replace that seal I am going to need instructions from you all and maybe borrow some of your tools. The pump was purchased/installed late 2014 and has 1000 hours on it.
    Last edited: Sep 23, 2020
  6. Jaws

    Jaws Active Member PLATINUM Sponsor

    Nov 13, 2007
    Sarnia, Ontario
    460 Sundancer 2002
    Cummins 8.3 6CTA
    After your write-up I had a good look at my SMX pumps. So far, so good with nine years on them (about 500 hrs. in the Great Lakes). I will be watching your reports but the SMX seem to pump a lot more water and they eliminate that shaft key. Running temperatures never vary, all day long.

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