Mercruiser Riser elbow gasket question

othelloears

Petty Officer 2nd Class
Joined
Jun 28, 2008
Messages
123
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
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Mercruiser Riser elbow gasket question

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

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04fxdwgi

Senior Chief Petty Officer
Joined
Jun 10, 2011
Messages
754
Re: 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

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.
 

othelloears

Petty Officer 2nd Class
Joined
Jun 28, 2008
Messages
123
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?
 

04fxdwgi

Senior Chief Petty Officer
Joined
Jun 10, 2011
Messages
754
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?

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.

 
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