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  1. #1
    Petty Officer 2nd Class
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    Default Mercruiser Riser elbow gasket question

    I am replacing the manifolds and risers/elbows on my 1984 Mercruiser 228 and can't figure out which gaskets to use between the manifolds and riser.

    They sell 3 different. (4 hole, 2 hole and no holes/blocked)

    Mine is full raw water cooled so i assumed I need the one with 4 open slots. The one with 2 open slots seems to be the most common.

    Please help

    Thanks

  2. #2
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Mercruiser Riser elbow gasket question

    Have a look at this Merc Service bulletin, it explains which gaskets to use.
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    Don S.


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  3. #3
    Senior Chief Petty Officer 04fxdwgi's Avatar
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    Default Re: Mercruiser Riser elbow gasket question

    Quote Originally Posted by othelloears View Post
    I am replacing the manifolds and risers/elbows on my 1984 Mercruiser 228 and can't figure out which gaskets to use between the manifolds and riser.

    They sell 3 different. (4 hole, 2 hole and no holes/blocked)

    Mine is full raw water cooled so i assumed I need the one with 4 open slots. The one with 2 open slots seems to be the most common.

    Please help

    Thanks
    The correct ones for my 7.4 w/ raw water cooling are the 2 slot ones w/ 2 small holes. Slots go on side to side with the 2 little holes facing fore and aft.

    The 4 slot ones are used when riser blocks are used between manifold and riser elbow. They are to go between the riser block and riser elbow, with the 2 slot ones between the riser block and manifold.

    The no holes ones are used when you have fresh water cooling (and should be used with the S/S block off plates for strength) and go between the risers and manifolds to isolate the raw water from the engine coolant.
    '92 Chaparral 2550 SX Sport
    454 BBC Mercruiser Bravo 1
    Tow with '04 F150 Larriat SuperCab 4x4 5.4 Triton
    US Coast Guard Aux.

  4. #4
    Petty Officer 2nd Class
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    Default Re: Mercruiser Riser elbow gasket question

    You guys are great thanks

    I have to lok at the boat but in think I need the restrictor 2 slot because I have the connection frm the riser to the termostat.

    Do the slots go fore and aft or the big slots?

  5. #5
    Senior Chief Petty Officer 04fxdwgi's Avatar
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    Default Re: Mercruiser Riser elbow gasket question

    Quote Originally Posted by othelloears View Post
    You guys are great thanks

    I have to lok at the boat but in think I need the restrictor 2 slot because I have the connection frm the riser to the termostat.

    Do the slots go fore and aft or the big slots?
    The correct ones for my 7.4 w/ raw water cooling are the 2 slot ones w/ 2 small holes. Slots go on side to side with the 2 little holes facing fore and aft.

    '92 Chaparral 2550 SX Sport
    454 BBC Mercruiser Bravo 1
    Tow with '04 F150 Larriat SuperCab 4x4 5.4 Triton
    US Coast Guard Aux.

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