Riser gaskets

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
If you are using OSCO, use their recommendations.<br />If you are using Mercruiser manifolds and gaskets use their recommendations.<br />Different gasket materials creates different methods.
 

Olds Eddie

Petty Officer 2nd Class
Joined
Jan 30, 2005
Messages
194
Riser gaskets

Hello All! I am putting my new engine in the boat and had a question. The closed cooling system I have uses a block-off gasket for the risers. The last ones I used were a metal shim with gaskets bonded to both sides. The new ones I got are a thick green fiber material. I am not sure I trust them to handle cooling system pressure. What has your experience with these gaskets been like? Also Osco recommends Loc-Tite flange sealant on this joint, but I think I heard somebody say 'NO SEALANT!'. Thanks
 

yoced

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Oct 8, 2003
Messages
142
Re: Riser gaskets

What Don said.<br /><br />Osco does not 'recommend' Loc-Tite flange sealant on the joint. Osco recommends a dry surface - <br /> - But, when on the phone, customers will often ask questions like 'but is it ok if I use sealant anyway..' or 'if i am going to use sealant anyway, what do you recommend..'and the Osco sales people will try to stear them away from silly-cone and into something like permatex #2 or some other very thin product.<br /><br />The thick C-4401 material that Osco uses for the block off gasket will work quite well under the closed cooling scenerio - as long as you retorque the riser after it gets warm. Maybe even retorque after a few hours of running also. That gasket material is very hard, and likes some time to take a set. I find it useful to leave bolted on for a few days first before it the parts are run, but most folks do not like being that patient.<br /><br />If you are worried, you could return your thick gasket for a set of thin gaskets with a metal shim, but it will cost more.
 

Olds Eddie

Petty Officer 2nd Class
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Jan 30, 2005
Messages
194
Re: Riser gaskets

Thanks for the input. I will use the green gaskets with the recommended waiting period and re-torque. I have made it a habit of re-torqing the manifold gaskets as I am running spacers between the block and manifolds, and with two gaskets to compress it just made sinse to do so.
 

Manipulator

Senior Chief Petty Officer
Joined
Apr 11, 2005
Messages
743
Re: Riser gaskets

I wondered about this as well. I had a riser crack and had to replace it. I bought an Osco replacement. It said to put it together without sealant, but when I took the old factory one off, it had sealant on the gasket (both sides). I used sealant (permatex) when installing the new one and had no problems. Just don't cake it on.
 
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