cast iron to stainless exhaust components

[Brian Fitzpatrick]

What is the opinion of adding a 316 stainless steel exhaust mixer elbow to an existing cast iron riser?

The attached photo is a Yanmar 6LY2AM-STPC installation I have. The mixing elbow has to be replaced because of it’s design. This is the way we purchased it, and I need to correct it. I can get a stainless mixing elbow made locally that will put the injection on the down hill side of the high point to prevent flooding the turbo when it leaks.

The other engine looks worse. I don’t know who designed it, but the Starboard engine has less than 12″ of spillover height.

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[Brian Fitzpatrick]

Thank you.

I was planning on salvaging the cast iron bend out (dry) of the turbo and adding a stainless riser & mixing elbow with more rise, and drain downhill in the exhaust exit if (when) it leaks internally.

I read Tony’s Tips on exhaust systems and recognize this is a dangerous design as it exists. I want to change that.

Is there an issue with electrolysis between cast iron and 316 stainless? Would the different coefficients of expansion of stainless and cast iron induce cracking? Is it not advisable to mix cast and stainless in an exhaust system?

When you say “do it right”, are you meaning go all stainless from the turbo exit to the mixing elbow exit?

thank you.

[Tony Athens]

Why not just do it right? You have plenty of room, so consider yourself lucky ( many installs do not)… .. You do realize that if one one those risers take out just one your engines you are up craps creek to the tune on $40K ++.. The 6LYA2 version is no longer supported well ( not that it ever was) and it cannot be rebuilt as the block is a true “throw-away” in the worst sense…

[Author]

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