Need advice on water pump replacement

Discussion in 'General Motoring' started by Larry, Jun 15, 2006.

  1. Larry

    Larry Guest

    My '96 SL has an intermittant coolant leak which I traced to the
    water pump area. It only seems to leave a small puddle when it has
    been sitting in my driveway for a couple of days - it doesn't seem to
    leak while running or leave a spot during the day at work.

    Since the pump has over 100K on it, I bought an aftermarket
    replacement to change out this weekend. It came with an 0-ring type
    gasket. Would you use any sealant on this, and if so, what type?


    Larry, Jun 15, 2006
  2. When I changed out my water pump ('95 SW), I used just a thin layer of
    Permatex on both the water pump and engine block flanges. It's been
    over two years now, without a drop leaking...
    William Hughes, Jun 15, 2006
  3. Larry

    Private Guest

    With respect, Permatex is a brand and not a product. They market a wide
    range of products some of which are suitable for this application.

    IMHO proper installation of O rings require some type of lubrication in
    order to allow the rubber to squirm or move into place as the part is
    tightened, and also to prevent the rubber from being cut or abraded. You
    also do not want the ring to seal or bond itself to the housing as you may
    need to remove it at some future time. The best product will vary according
    to specific application but in general almost anything will work, many
    people use grease as it will also help to hold the ring in place as the part
    is positioned but RTV silicone also works well, plain oil or in this case
    coolant will also work. Most of the Permatex gasket glues will work but
    some of the hardening types will be difficult to remove if you need to
    remove the part in the future. Do not overuse anything as the excess will
    only contaminate the contained fluid, (in this case the coolant). As a
    general rule lubricating with the contained fluid is seldom wrong.

    I would also add that water pump seal failure is often caused by the drop
    out of the abrasive silicate used in standard aluminum compatible antifreeze
    coolant to reduce galvanic corrosion between the iron and aluminum parts of
    the cooling system. Now would be a good time to drain and flush the cooling
    system then wash with a solution of Calgon dishwasher detergent before
    repeated thorough flushing and installing new non-silicate type long life
    coolant. It is important to remove ALL of the standard coolant before
    installing most types of long life coolants as most are incompatible.

    Those who continue to use standard aluminum compatible coolant and
    especially those who use old coolant will probably need to change their
    water pumps sooner than those who do not.

    Happy trails, YMMV
    Private, Jun 16, 2006
  4. Around here (San Antonio, Texas) "Permatex" is the term used
    generically to refer to any silicone-based sealant. In this case, the
    black, high-temperature, oil-resistant variant. Comes in a blue
    squeeze tube. You are correct; I should have been more precise - not
    everybody speaks Texan...
    William Hughes, Jun 17, 2006
  5. Larry

    Private Guest

    IIRC, In the pre RTV days 'Permatex' #2 was a black general purpose tacky
    non-hardening gasket glue. I think it was called #2 because it got all over
    everything and was hard to get off your hands or tools, I don't remember a
    #1 :)
    Private, Jun 17, 2006
  6. Larry

    Bob Shuman Guest

    Permatex #1 is still sold. It is a brown hardening gasket sealer (as opposed
    to the black non-hardening silicone based sealant for the #2). Permatex
    also makes a Blue RTV and a black high temperature RTV sealant. I generally
    use a little blue RTV in the channel and on the mating surfaces with water
    pump O-rings.

    Bob Shuman, Jun 17, 2006
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