Chipleykk wrote:

> I recently purchased a 1991 Sea Ray 185BR with the 4.3 LX V6 Alpha 1 drive
> train.  Boat has about 200 hours. Boat runs great but it has annoying rattle in
> the starboard exhaust pipe below the exhaust bellows at idle.  Sounds like
> gravel rolling around in a tin can irregularly.  I tracked it down with my
> wife's stethoscope.  She was not very happy!

> Does anyone have idea what this is?  Is there a flapper valve in this pipe that
> could rattle?

> Any info would be appreciated.

The flapper is mounted in a rubber bushing inside the exhaust pipe. The
usual cause for this rubber to fail is excessive exhaust pipe
temperatures. Even though the engine may be running cool enough, the
water pump may not be supplying enough water to cool the exhaust. Don't
ignore a noisy flapper because the only thing left, could be the
stainless pin that held the valve.[ water backflow into an engine is no
party ] Also check your exhaust elbows for rust, if used in salt water.