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What gaskets for risers? Green or Silver?-gctid387017

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    What gaskets for risers? Green or Silver?-gctid387017

    My turn in the overheating rodeo we've been having around here!

    History: Boat was out of water recently, put on new heads due to stuck valve, corroded seats etc. Suspected failed oil cooler was replaced as well. New impeller, thermo, Circulating pump too.

    Boat has been running fine at harbor speeds, but overheating at the higher rpms, seemed like classic water flow problem.

    Took off the risers yesterday, found the mechanic used a restricted gasket between spacer and riser---hmmmm! Always had 4 open port gaskets before, could explain some low flow!



    Also, obvious water breaching at gasket points into the exhaust port too---



    These are new risers, 9 month old manifolds, old but good condition spacers. Anyway, gonna clean up mating surfaces and reinstall with proper gaskets, hope we're running cool!

    They swear by the green paper Sierra gaskets with a lot of permatex, I've used the silver thin ones in the past though. Any opinions?

    #2
    I use silver, no sealer, re-torque after 10 hours and NEVER had a problem.

    The above is assuming good condition, flat matting surfaces.

    Your results may vary.
    " WET EVER "
    1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
    mmsi 338108404
    mmsi 338124956
    "I started with nothing and still have most of it left"

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      #3
      Yes, I think I'll be going back to dry silver. I liked the idea of the extra thickness with the paper and ability to slop on the p-tex though!

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        #4
        There are those on this board who swear by using aviation permatex on riser gaskets. Personally I am of the mind set that if the surfaces are good and you use a quality gasket you won't need sealer.But again, to each there own.

        [img]/media/kunena/attachments/vb/690634=28295-advice.jpg[/img]
        " WET EVER "
        1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
        mmsi 338108404
        mmsi 338124956
        "I started with nothing and still have most of it left"

        Comment


          #5
          Although "they" say not to use sealer on these gaskets, years of experience have me using sealer on the "green" gaskets and no sealer on the silver.

          I have Osco center risers and can only get green, and with a "LITTLE" (paper thin) sealer on them, no leaks / seepage at all.

          I wish I could find the silver though - I think those are superior to the green.

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            #6
            Those risers look very similar to the ones on my 4.3 l Merc. The gaskets, however, look nothing like the ones that I've installed on numerous risers thro the years (both on my 470 and 4.3). My gaskets cover the entire mating surface, and have always recommended that a sealer be used on BOTH sides of any openings... yep, that's a lot of sealer (a double bead on each side of any opening) and will probably take you about 5 minutes per gasket side. You have to install it on both sides of the gasket. In 35 years I've never had a gasket failure when applied like this, so I'll continue until I get the calling. BTW, these gaskets come with the risers as part of the package.
            Bob Hawes.
            Kelowna, B.C.
            1998 Trophy 2052 WA
            4.3 Vortec, A1 G2

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