Manifold/riser installation

[4 Reel]

Hi all. I just picked up new (GLM) manifolds & risers for my 98 5.0 merc.Alpha 1 raw water cooled.Have a couple of questions about the manifold to riser mating surface, do i need to remove the paint from this area & also (I know this has been kicked around before)the gasket is installed dry, no sealant is that correct? Also the water paths of the original merc equipment and the aftermarket GLM's appear to be the same but the original gaskets had 4 equally sized oval water passage holes, the new gaskets have 2 equally sized oval holes & 2 very small holes. It seems to me like i would be restricting the water path by half with these gaskets??? Thanks in advance.

 

[Haut Medoc]

Re: Manifold/riser installation

The holes go fore & aft....No sealant....I would remove the paint....JK

 

[KaGee]

Re: Manifold/riser installation

Yes, remove the paint. Both surfaces should be shiney. Place the riser gasket with the larger holes towards the front of the boat. It forces the water up and over the elbow, giving it better cooling.

 

[4 Reel]

Re: Manifold/riser installation

So i guess i need to use the gaskets that came with the manifold set (2 large oval & 2 small holes) as opposed to the original OEM Merc. riser gaskets that have the 4 large oval holes. This wont affect cooling at all?

 

[Haut Medoc]

Re: Manifold/riser installation

Yes................NO ....JK

 

[crazy charlie]

Re: Manifold/riser installation

I dont favor a dry riser gasket because they usually seep some and develop a rust ring around the bottom of the riser.Sealant is not recommended because there is a great chance of human error that too much sealant is used and it squeezes into the water passages as the riser is tightened down.This is why I favor spraying the gasket with an aerosol sealant called Hi-tack.I think it is made by permatex.

 

[Bt Doctur]

Re: Manifold/riser installation

A thin coat of "Aviation Permetex" work nice too. Avoid silicones!!!!!

 

[4 Reel]

Re: Manifold/riser installation

BT, Does 'aviation permatex' go by another name?

 

[KaGee]

Re: Manifold/riser installation

Originally posted by 4 Reel:<br /> BT, Does 'aviation permatex' go by another name?

It's actually Aviation Sealant by Permatex... NAPA has it.<br /> LOOK HERE