You don't say anything about what engine or outdrive you have?

On a merc the V engines do connect together at the bottom of the Y pipe.
The two holes on the sides of the outdrive transom plate are relief holes.
It does sound like some of the debris from your manifold and riser got down
there. If you have a V engine you should replace both manifolds and risers
if one side went. While you have them off and the flaps out of the Y pipe
try using a garden hose and spray handle to clear out the relief holes.

"ToneJohn" wrote in message
...
On one side of my exhaust pipe the flap was completely burnt off. I
realized that this was from a corroded manifold and elbow, I'm in the
process of replacing them and also the flap. I know that the exhaust pipe
meets/joins together right before the transom, what I also noticed is that
the water when on the earmuffs only expelled from one side of the
outdrive. My thought is that there is debris clogging up one side at the
bottom of the exhaust pipe, does this sound possible? If so, what is the
best/easiest way to clear the debris from the bottom of the exhaust pipe?
I have never seen an exhaust pipe before installation so I'm not sure how
big the openings are at the bottom also where it comes out the outdrive.
Any help is greatly appreciated.

-Matt