Riser replacement intervals

[tonyiiiafl]

Merc 454’s, 3/4 closed cooling. Engine and manifolds have coolant, risers raw water. Less than 50 hours per year right now. What is your take on riser replacement? Not a fan of removing and inspecting as all the labor involved may as well replace. When do you change yours?

Tony

[buster53]

FWIW, pretty sure what you have is considered a full fresh water cooled system, not a 3/4 system. You can include the manifolds in your closed loop, but never heard of any system that included the risers in the system. I don’t think that is even possible.

So where do you use your boat? Fresh, salt, brackish? How often do you flush the engine? How often should you change the risers? Could be as short as 3 years or could be easily 10 years.
It’s not really an hour thing…more like a calendar issue.

[tonyiiiafl]

Correct, a full system. Also, I wished risers would be inclusive, but the raw water has to go somewhere. Salt water, flush at end of season, for winter layup. I was thinking of a 5 year replacement cycle as insurance of sustainability

[Viper]

Buster is correct, you have a full fresh water cooling system. The typical benchmark for considering salt water application exhaust component replacement is 5 years. As mentioned though, things can go wrong sooner or not be an issue for 10 years or more. When it does though, it can result in a catastrophic engine failure. The 5 years comes from field experience, anything over that is typically viewed as running on borrowed time though an annual inspection can help ease one's mind. In the end it's one's comfort level and wallet that dictate.