Nissan 78hp question

[Howard H.]

Is there any rule of thumb regarding the removal and inspection of the exhaust riser on the Nissan 78 hp engine? My 27 (1986) has a bit under 1,000 engine hours on the clock. The boat was used for the first half of its life in salt water and the second half in brackish water. There is no obvious problem with cooling as of this post date.
Howard H.

[AlMar]

While I have no experience whatsoever with your engine, I don't see how it would be much different from any other riser once it's become friends with salt water. As a rule with gas engines, and salt water, we would replace them every 5 years regardless of hours, as it is the salt doing the corrosion more than the time. Looking forward to hearing from some others on this.
AlMar

[Howard H.]

My exhaust riser must be a miracle, for I believe that it's the original one (1986). The engine runs just fine, thank you, with no overheating problem. perhaps at the end of the boating season I'll remove it and see what really is going on in there. There are no pencil zincs in the heat exchanger as far as I can see, and that, too, is original or at least 8 years old (the time that I have owned the boat).
Let's see what others have to say about this topic.
Howard