Electrolysis and manifolds

[MCL]

Hi

Both of my manifolds cracked due to freezing(old owner).Im replacing the engine and going to FWC it.I want to get alum exhaust manifolds and use the old risers.The old risers are oem mercruiser cast iron and only a couple of months old.I know that both materials expand different,but I use a gasket-ssplate-gasket between manifold and risers to allow a bit of stretch.

I asked both hge and glm about the issue.Glm answered that I must use both parts alum because of electrolysis.Hge replied that it would be ok.

Anyone have a insight of this.Cast iron heads have alum manifolds and their gaskets hold just fine.Only thing om concerned about is electrolysis,what could happen?

 

[nola mike]

Re: Electrolysis and manifolds

my 170 has an iron head, alum mani, iron riser from the factory. all appear original, 25 years old...

 

[MCL]

Re: Electrolysis and manifolds

Anyone else,I would like to know exactly could go wrong.

 

[zbnutcase]

Re: Electrolysis and manifolds

Unless your planning on closed cooling your manifolds, (known as a full system) I would stick with iron manifolds.And if you are going to run the manifolds in a closed setup, remember it requires a MUCH larger heat exchanger, and higher volume seawater pump. I prefer half systems myself.