Sealant tabs

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Northstar Engines and System Technical Discussion Discussion, Sealant tabs in Cadillac Engine Discussion; Hi I have a 93 SeVille STS.. I have a slight coolant leak.I don't know where its coming from but ...
  1. #1
    GeorgeGN is offline Cadillac Owners Member
    Join Date
    Feb 2003
    Boston Mass

    Sealant tabs

    Hi I have a 93 SeVille STS.. I have a slight coolant leak.I don't know where its coming from but every couple of weeks the low coolant message comes on.
    I bought a pkg of those pellets. I dont think putting them in the coolant overflow tank is the best thing to do.There is no radiator cap that I can see. Should I pull the visible upper hose and drop them in there.. I dont want to clog the thermostat..
    Thanks George

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  3. #2
    AKPsiMC03's Avatar
    AKPsiMC03 is offline Cadillac Owners Enthusiast
    Join Date
    Feb 2003
    Middlebury, CT
    no radiator cap. those things do more harm than good. they gum up everything. start sniffing around for a leak.

  4. #3
    Bruce Nunnally's Avatar
    Bruce Nunnally is offline Cadillac Owners Member
    Automobile(s): 2008 Cadillac STS-V Spectre CAI, Corsa
    Join Date
    Feb 2003
    The sealant tablets go into the lower radiator hose on the northstar system. Here is the shop manual warning for the Northstar:
    This engine uses DEX-COOL® and GM coolant supplement (sealant) P/N 3634621 specifically designed for use in aluminum engines. Failure to use the engine coolant supplement (sealant) and the approved coolant antifreeze could result in major engine damage. When refilling the cooling system, add three pellets of the engine coolant supplement sealant GM P/N 3634621 to the lower radiator hose

    More info here:

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