Hi Guys,

Just wondering what material is going to be best to use for the water inlets? I'm concerned about galvanic corrosion as I'm raw water cooled and they are aluminum.

I got these second hand but stock they come with stainless bolts (riser to manifold), stainless pipe fittings for the water hoses and brass pipe plugs. I have the pipe plugs but need an npt to hose barb for the riser. The manifolds have those 90 deg plastic fittings with the blue drain plugs. Seems like stainless is one of the worst materials to have in aluminum threads?

Is thread tape good enough to stop the corrosion? Or would the #3 aviation gasket paste be better? Have read that never sieze should not be used in a marine environment as it becomes "never come apart?

I've read a lot of conflicting theories so am asking you guys as this place has a ton of boats with aftermarket manifolds and risers.

Stainless with aluminum is the way to go ....get rid of that brass...it doesn't play well with aluminum. And use plenty of anti-seize on any threads that are going into the aluminum.

Ok, thanks.

I see you are in NJ? Saltwater? Stainless and aluminum in salt water can be problematic, as you were already kind of thinking. Thread compounds will help, but I am not a fan of never seize. My go to is Permatex Aviation form a gasket. Some of the NPT to barb fittings are also available in aluminum, not that aluminum on aluminum in salt is great either, but same applies with thread compound.

Hi, yes I am in NJ and will be in saltwater.

I have purchased fittings in SS, Brass and Aluminum. When I came across the Aluminum ones I thought they could be the ticket. But when I have them in my hands they are really light and thinner walled than the others. So I am concerned that with corrosion, they could snap easily when removing. I have seen people stating the Al AN fittings only lasting a couple of seasons.

There is so much conflicting info out there. Even the manufacturer ships them with both SS and Brass.

I have recently found out about the Aviation gasket and purchased some. When applying do you just coat the threads and then install? The bottle states to wait a minute or 2 but I am thinking that is for when using as a gasket.

Thanks for the reply and info.

My 496/8.1 had factory aluminum manifolds with aluminum fittings in them from Mercury. They were 15 years old when I changed them out, just because I found a new set.

^ Like above, I had aluminum fittings in my aluminum Eickert Headers and it was 14 years or so before I had any fitting issues/corrosion leaks, keeping in mind I do flush engines religiously. For fitting installs, I usually just liberally coat the threads and install. I am of the mind that letting the liquid form find the pockets in this manner before it sets up should work better. Wait time is for gaskets, as you said.

Thanks for the confirmation. I will see if I can find some heavier duty aluminum fittings.