Silicone to replace power head base gasket?

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  • adam1961

    Canada Member - 2 Years
    Replies: 366
    Topics: 88
    #4854

    Does anyone use some kind of silicone or RTV in place of the base gaskets on Classic OMC motors? I find myself going through many gaskets on the motor that I run on my racing runabout. It seems I am always pulling the power head for one reason or another. Is it possible to use a sealant, or should I just keep replacing the gaskets( one on each side of the stainless baffle) ?

    Adam


    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #41034

    Adam, I would not try to substitute RTV/sealer for base gaskets. You could try just coating the new gasket on both sides with grease so the powerhead will come off without damaging the gasket during future repairs.


    drifter


    Replies: 201
    Topics: 132
    #41035

    On a similar note, I have a repair manual that shows a head gasket (on a 57 Johnson 10hp) being replaced with anti-seize compound covering both sides of the gasket. I never tried it but wondered why they did this. Is this a normal repair practice?


    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #41047

    Drifter, would love to know what kind of manual would make a recommendation like that….Some of that anti-seize stuff can actually promote corrosion when mixed with the aluminum and salt water. Yes, I realize that the anti seize company does make aluminum compatible products, but they would have little value when it comes to sealing a head gasket.
    The best stuff to use when sealing head gaskets is the OMC/Merc gasket sealing compound. Using the gasket sealer around the outer edges of the head gasket is all that is needed, this will not help seal a fault in the cylinder to head surfaces, although it surely won’t hurt to apply there as well.


    Mumbles


    Replies: 5764
    Topics: 298
    #41049

    Aluminum paint used to be the sealer of choice for automotive copper composition head gaskets! ☺


    The Boat House


    Replies: 4550
    Topics: 111
    #41058

    Adam1961
    Sent you a PM.


    drifter


    Replies: 201
    Topics: 132
    #41065

    Well, I was almost correct. The manual is a book titled "The Classic Outboard Motor Handbook". Page 91 shows a photo of a man brushing anti-sieze on a 1958 Johnson 10hp on the block where the head gasket mates to the block. The photo caption reads:" A gasket sealing lubricant is applied to the water jacket and cylinder assembly surfaces".
    I always thought this was weird.
    Drifter


    amuller


    Replies: 1055
    Topics: 163
    #41097
    quote fleetwin:

    Drifter, would love to know what kind of manual would make a recommendation like that….Some of that anti-seize stuff can actually promote corrosion when mixed with the aluminum and salt water. Yes, I realize that the anti seize company does make aluminum compatible products, but they would have little value when it comes to sealing a head gasket.
    The best stuff to use when sealing head gaskets is the OMC/Merc gasket sealing compound. Using the gasket sealer around the outer edges of the head gasket is all that is needed, this will not help seal a fault in the cylinder to head surfaces, although it surely won’t hurt to apply there as well.

    I’ve wondered if the copper loaded anti-seize is really OK to use with aluminum. Is that what we are talking about here?


    PugetSoundBoater


    Replies: 900
    Topics: 105
    #41098

    You do not want to use anti sieze with copper on Aluminum in it due to the galvanic corrosion/dissimilar metals issue. I use Jet Lube Marine Grade Non Metallic Anti sieze.Fastenal stocks it. Locktite makes one also.

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson


    collectorinspector


    Replies: 145
    Topics: 21
    #41108

    I do not believe that silicon or RTV squeeze of any type should ever be used……….

    Plenty of old school gasket/sealant/preparation with some attention to detail before assembly is the ONLY thing required.

    Just saying.

    BnC

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