Cracked and severely corroded exhaust riser for a small diesel auxiliary on a 30-foot sailboat. If it’s this bad the outside, just imagine what the inside looks like. That corroded fuel shut-off control line resting against the of the riser isn’t looking too good either.
Engine manifolds and exhaust risers should be periodically removed, pressure tested, and fully inspected for corrosion, and clogging, as failure here can easily cause catastrophic engine damage. This should be considered standard maintenance, particularly with systems operating in salt water. How often depends on vessel location and use, however at a minimum they should be removed every four years (more frequently depending on age).