Manifolds & Risers

[jp36lr33]

How can I tell when it is time to replace the exhaust manifolds and/or risers on a Mercruiser engine?

[whotookmyhandle?]

How can I tell when it is time to replace the exhaust manifolds and/or risers on a Mercruiser engine?

In Florida you should pull the risers and inspect every year. Four years on a set is pushing your luck.

Look at the gasket area between riser and manifold for weeping or corrosion. If its leaking outside its leaking inside.

[yottyboy]

I have about twenty years on the set on my OMC.

[chuck34]

Is your engine RWC or FWC?

[jp36lr33]

Is your engine RWC or FWC?

It is a raw water cooled engine(5.0 liter Mercruiser) with 700 houurs on it. I trailer the boat and religiously flush with fresh water after each use. I also occasionally flush with Salt-Away. Yesterday I pulled the starboard exhaust manifold and riser. I found one of the passages competely blocked with scale but it seems to come out fairly easily.