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you may term it a half system but it is properly referred to as a full system....the elbows will Always be on the raw side....on a half system, only the block is included in the closed (antifreeze) side...a full system adds the manifolds to the closed side....finally, the risers, if equipped, usually go in the raw side. And 2X on Jeff's number
I have heard different opinions, but want to throw this out here:On a full FWC engine, should you replace both the risers and manifolds every five years?
I had a boat with 2x 454s and every 5 years replaced the risers and manifolds (pretty expensive). I read some opinions that since the manifolds are FWC, they will last a lot longer than the risers (or elbows).
Some say change the mani's every time; others say every other time you change the risers; some say the mani's should last the life of the engine.
I now have a boat with a single 5.7MPI...it's coming up on time for me to replace risers....so am contemplating this....thoughts?
Always good to err on the side of caution. I think in salt water, it would be good to replace risers and elbows every 5 years. I currently go ten years on mine but I'm mainly in fresh water at the head of the Chesapeake Bay.
FWC cooled manifolds live in an environment that is similar to that seen by the heads (operating temps, corrosion, etc.) except they do not have valve seats to wear or fail and they do not see combustion pressure stress and overheat stress. So it would make more sense to change out heads periodically than exhaust manifolds.....and no one does that!
Salt water cooled elbows and risers are a different story but don't worry about the manifolds.