Exhaust manifolds last forever, don’t they? Even if they do fail, it isn’t a major problem, right?


These are common reactions when people are asked about their boat’s exhaust manifolds. Unfortunately, exhaust manifolds and risers are extremely important. And ignoring them can potentially lead to expensive problems, perhaps even an engine rebuild / replacement.
There is an additional hassle; exhaust manifolds and risers are normally damaged by corrosion, so they’re not covered by your insurance policy.
All of this makes the outlook seem rather bleak. It’s not as bad as it seems, though. All that’s needed is a change in attitude. Rather than seeing it as a “sealed for life” component, view an exhaust manifold as a serviceable item to be replaced at regular intervals. If you do this, major problems can be avoided.
How long will a manifold last? Obviously the way you use your boat will play a large role, as will the type of water it’s on. Saltwater boats are going to see a shorter manifold life when compared to their freshwater counterparts.
Most experts suggest that a manifold will have a life expectancy of six to eight years. However, heavy use in saltwater can see this drop to as low as three years. While lightly used freshwater boats can get up to 20 years out of a manifold.
This is also assuming that your manifold is raw water cooled. While it is the exception to the rule, some engines have a manifold cooled by the engine’s fresh water/antifreeze coolant mixture. These obviously usually last much longer.
One thing is for certain, the older your manifold gets, the more likely it is to fail. Your best bet is to stay ahead of the game by having the experts at Affordable Marine Service inspect your manifolds / risers prior to any damage occurring.

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