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| Help on id of a noise, possible exhaust flapper?? https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=9391 |
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| Author: | vogs77 [ Mon May 28, 2012 7:27 pm ] |
| Post subject: | Help on id of a noise, possible exhaust flapper?? |
I have a clanky noise that is more noticable at idle and just off idle in the engine area. It is not internal engine noise. I have been reading a little about the exhaust flappers. Is this a common noise on a 1995 horizon 5.0mpi OMC/Volvo. I read someplace that they need to be removed, is this something I can do with the boat in the water. Do the risers need to come off? Are they at the top of the Y pipe? |
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| Author: | Surface Interval [ Thu May 31, 2012 5:34 pm ] |
| Post subject: | Re: Help on id of a noise, possible exhaust flapper?? |
I have the same boat/engine. I really doubt that they would cause a noise. They are located at the top of the Y pipe on each side. This is only a little bit above the water level, and you might be careful if opening it up while in the water. You can loosen the clamps and remove the elbows to see the flapper valves. Personally, I would not remove them, although some people do. The flapper valves are there to prevent water from surging backwards through the exhaust system and into the engine cylinders causing a hydraulic lock. I had the left flapper valve come loose and cause a significant loss of power by partially blocking the exhaust passage as it goes through the transom. If this is the case Volvo had a fixture to re-drill new holes in the top of the Y pipe and re-install the rubber bushings and pins that mount the flapper valves. The pins and bushings are a few dollars. It is a pretty simple procedure and definately not worth the significant cost to pull the engine to change the Y pipe. The bushings may disappear, the pins will probably remain in the exhaust system somewhere, and the flapper valve is too large to go through the transom. If your clanking noise is only in neutral it may be gear backlash in the outdrive. Mine has done this occasionally when warmed up. It has never been a problem. |
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