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Riser gaskets

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infinityron

Contributing Member
Quick question, I'm gonna be replacing my 90 degree cast iron elbows behind the risers on mercruiser 7.4 mie's. To get the hoses off, I will need to unbolt the risers from the manifolds to move the risers. I have the "fresh water cooled" system with center rise risers off the manifolds and no spacer blocks. I want to have the new block off gaskets in hand and I see they are pretty cheap, like $12 on ebay for two of them or $25 on amazon, but I don't think those are stainless and I don't know what is currently in there. Ok to go with these fabric gaskets (block off plates) or should I spring for Stainless block off plates?
 
get the SS ones and use 2 gaskets, 1 above and 1 below
Make sure to drain the riser and drain some A/F from the manifold FIRST
 
Bt Doctur said:
get the SS ones and use 2 gaskets, 1 above and 1 below
Make sure to drain the riser and drain some A/F from the manifold FIRST
Click to expand...
This may qualify as a really stupid question..I have in hand the ss block off plates and I ordered "mercruiser fresh water cooled gaskets" but in the gasket package, they included one total block off gasket and one slotted gasket. I have a complete closed "fresh water cooled" system so I'm uncertain about using the slotted gasket, even though all passages will be blocked by the ss plate and the other blocked gasket? Should gasket sealer be applied as well? I'm inclined to use a little.
 
with the ss plate any type of gasket will do just fine. I use permatex aviation sealant on both sides.. Just drain the manifolds BEFORE removing the riser
 
Bt Doctur said:
with the ss plate any type of gasket will do just fine. I use permatex aviation sealant on both sides.. Just drain the manifolds BEFORE removing the riser
Click to expand...
Thank you for your replies. I did one engine yesterday. I was pleased that both the riser and the manifold passages were wide open, without a lot of deterioration. I opted to use solid block off gaskets on both sides of the ss plate. I did use the aviation sealant, but I need to ask why you prefer that over the old fashioned Permatex orange stuff in a tube? I have done my own car and boat repairs for years, and I found this aviation stuff to be a tad messier and more difficult to use that a thin spread with my finger of the tube stuff.
 
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