I have EMI thunder exhaust. I have the older style that have the open cooling holes in the gasket mating surface. I took my boat for its maiden voyage today and ended up with milky oil. I broke down the exhaust and the gasket/mating area has failed. How do I clean out the crappy oil? And how can I make my exhaust not leak?

will take 2 oil changes at least to get the wet oil out. this may be a time for running waste oil since it is only gonna be in the engine 5 minutes. why did mating area fail? if the surfaces are bad, auto machine shop that does head work can reface the mating surfaces. i have cleaned up alum risers with my belt sander. the heat isn't extreme. you could epoxy up small pits. then a quikie leak test. stand manifolds up and fill the cooling passages with water till it is above riser joint and look for water running into exh passages. THEN run a hose around back of engine connecting the 2 manifolds water passages together. buy a ball valve at a plumbing supply store and install it in 1 of the feed lines from thermo hsng to manifold. whenever you shut engine off, flip valve open and drain exhausts. if running shaky exhausts you can never justify having water above your exhaust valves...