Got a problem at work with one of the Halmatic launches, twin Volvo TAMD63 diesels.
There is a "thing" in the exhaust the purpose of which is clearly to stop water going back into the engine when at rest, it sits in the middle of the oil-rig bore rubber exhaust hose, about half way between the turbo and the exit through the hull, and is full of strips of heavy rubber arranged in a ring which it would appear are supposed to blow out under the pressure of the exhaust gases, but collapse back as a valve when the engine is shut off to prevent water ingress. Trouble is they aren't blowing out (or rather they are, but only sometimes) - we think they are blocking off the exhaust gases causing a lack of power and clouds of smoke, having got it out it looks f***ed so we need to get a new one.
What would you call this "thing" so I can type it into Google and try and get half a clue where to get a replacement from? It isn't a standard bit associated with the engine so there's probably no point talking to Volvo about it. The guts of it appear to be replaceable without replacing the outer shell, the outer shell basically looks a bit like a big rubber silencer in the exhaust system.
Ta very much for any info