Exhaust Manifold and Risers

Torre

Hi Guys, I was wandering if anyone could advise me how often (Generally speaking) the Exhaust Manifold and Risers would need replacing on my 280 EC Volvo Penta 5.7 Gi-300 Petrol Engine thats "Raw" Water cooled and permanantly used at sea. The existing Exhaust system was replaced 4 years ago but the engine has done very little work in that period, maybe 80 - 140 hours. 
Externally all looks new and I have no issues with overheating, but as I've only had the boat for a Year and have no experience on the matter I thought someone on the Forum could assist. The Temp. Gauge when idling and running at 4,000 rpm plus remains constant at 150 - 165 deg. F.
Many thanks.

raybo3

Most likely 5 to 7 years assuming salt water. Might get lucky and squeeze a couple more years out of them.....

Torre

Thanks raybo3. That’s much appreciated. if I removed them for inspection i’d need to fit new gaskets so i’ll wait until next Year. Hopefully all should be well until then.