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Thread: Gasket Sealants

  1. #1

    Default Gasket Sealants

    Awhile ago I came across a post which in detail listed which gaskets and what kind of sealant should be used etc. I can't seem to find it. If someone can point me where it's located I'd appreciate it.
    Thanks

  2. #2
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    Default Re: Gasket Sealants

    Gasket Sealers)
    (Usually available at any reliable automotive parts type store)
    (J. Reeves)


    Do Not use any type of sealer on outboard carburetor or intake manifold gaskets as this would cause blockage of various fuel/air passageways. Also, there are new type gaskets, including head gaskets, which are used through out the engines that are coated with a substance that gives a shinny appearance to them. These gaskets are coated with a self sealer and are to be installed as is.... no sealers! Older style head and fuel related gaskets that are not coated with this substance are to be simply coated with oil.... nothing else.

    All other gaskets (hopefully I've not overlooked anything above) should be coated with Gasket Sealer (the type that comes in a can that has a small brush in its screw off cap). This also pertains to some water pump installations that use a gasket between the plate and the lower unit housing.

    Marprox Sealer 1000 or OMC Adhesive or Boat Armor Sealer 1000 (same substance)[See Below Note] should be used on any metal to metal (Unless GelSeal Is Called For) or metal to plastic surface (such as impeller hsg to plate, and plate to lower unit surface) to eliminate air leaks. It should also be used on the Spaghetti tubing that is used on many powerhead crankcase halves, lower unit skegs, etc. I have found that this substance works quite well on various "O" Rings such as what are found on lower unit carrier and upper driveshaft bearing housings (Note that this substance is obviously not to be used on all "O" Rings). This substance also works quite well in sealing the surfaces between the lower unit and the exhaust housing to which it attaches, eliminating the unsightly water spray between the two after completing a water pump installation.

    NOTE 1: I am under the impression that Marprox Sealer 1000 and Boat Armor Sealer 1000 is no longer available.

    NOTE 2: OMC Adhesive is now Bombardier 3M Product #847 and may be listed as Scotchgrip 847, part number 776964

    DO NOT use any sealer on the large "O" Rings that are used on the upper and lower crankcase heads (The housing/heads that slide over the top and bottom of the crankshaft). On those "O" Rings, use only a coating of grease.

    The exception of surface to surface contacts pertains to the later model matching crankcase (block) halves (which does not incorporate spaghetti tubing) which call for "Gel-Seal", or any other surface that calls for Gel-Seal. This substance seals in the absence of air, and if called for, must be used. One other form of Gel Seal that can be substituted is "Loctite #518". Nothing else that I know of will do!


    I advise against using silicone or permatex on a outboard engine. It simply will not function properly. The exception to this (as per OMC's recommendation), is to use the black Permatex (heavily) on the gasket 306242 which seperates the inner exhaust tube from the exhaust housing on the 1959 35hp and 1960 to 1970 40hp OMC outboards.
    We occasionally have questions. If you fail to answer, it may affect ours.

  3. #3
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    Default Re: Gasket Sealants

    Quote Originally Posted by joereeves View Post

    All other gaskets (hopefully I've not overlooked anything above) should be coated with Gasket Sealer (the type that comes in a can that has a small brush in its screw off cap). This also pertains to some water pump installations that use a gasket between the plate and the lower unit housing.


    I advise against using silicone or Permatex on a outboard engine. It simply will not function properly.
    What about PERMATEX Aviation Form-A-Gasket Sealant? It comes in a can that has a small brush in its screw off cap:

    Click image for larger version. 

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  4. #4
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    Default Re: Gasket Sealants

    Quote Originally Posted by Klink View Post
    What about PERMATEX Aviation Form-A-Gasket Sealant? It comes in a can that has a small brush in its screw off cap:

    Click image for larger version. 

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    No doubt the same substance as the gasket sealer in a can with a brush attached to its screw on/off cap as I mentioned.

    I'll revise my info on that in my database.

    The permatex I spoke of pertained to the super heavy substance that comes in a tube and dates back to the Ford "Model T"..... In thinking about that, so do I.
    Last edited by joereeves; 12-12-2017 at 05:50 PM.
    We occasionally have questions. If you fail to answer, it may affect ours.

  5. #5
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    Default Re: Gasket Sealants

    Quote Originally Posted by joereeves View Post

    The permatex I spoke of pertained to the super heavy substance that comes in a tube and dates back to the Ford "Model T"..... In thinking about that, so do I.
    I had two tubes of that stuff for 40 years, Permatex 1 and 2, one sets hard and other remains flexible.

  6. #6

    Default Re: Gasket Sealants

    Should I use this on head and head cover gaskets?

  7. #7
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    Default Re: Gasket Sealants

    Quote Originally Posted by solarman View Post
    Should I use this on head and head cover gaskets?
    Like Joe Reeves said above:

    " there are new type gaskets, including head gaskets, which are used through out the engines that are coated with a substance that gives a shinny appearance to them. These gaskets are coated with a self sealer and are to be installed as is.... no sealers!"

    If they do not have the coating, I do use that Permatex Aviation Form-a-Gasket liquid. I've used it on the Johnson Evinrude head cover gaskets on my early 90's 25's and 115, and Yamaha 115.

  8. #8

    Default Re: Gasket Sealants

    Would this be considered the new style gasket that wouldn't require sealant?
    Click image for larger version. 

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  9. #9
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    Default Re: Gasket Sealants

    It looks like its the type that does not need gasket liquid, but others more experienced will have to tell you. Contact the manufacturer, or look it up in their literature online, they have to have specs on it.

  10. #10
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    Default Re: Gasket Sealants

    The gasket that doesn't require sealer has "use no sealer" wrote on it. The surface is also very shiny.

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