OMC Stringer Exhaust Leak Behind Engine-Bell Housing?

[Sax6thave]

Summary-1984 Renken,305 Chevy/OMC, Rotted stringers in Bilge area causing mounts to drop into the fiberglass, ripped boot, took on lots of water, made it to the trailer and home. I planned to rebuild the stringers under the engine and intermediate until I cranked it at home. I have a very noisy sound, exhaust leak?, coming from the bell housing area. I have checked the exhaust from the engine back and all is intact. At idle, the noise is so loud, you would think piston slap or major engine damage. With water, I ran the engine 15 minutes at various rpm and found the noise. The thin metal plate on the bottom of the bell housing is rattling and changes to a quiet "exhaust leak" at different rpm. I can pull back on the metal plate at idle, boot is removed, and the sound is faint but still there. I didn't initially plan on pulling the engine, however, my research on this setup leads me to believe the exhaust channel on one side of the bell housing is cracked allowing exhaust to leak behind the engine. 130-140 psi on every cylinder, no overheating after 15 minutes, purrs at idle up to 3,000 rpm, cannot feel exhaust or see water coming out of the bell housing while running, CONFUSED! Any ideas? Putting the boat in the basement today with plans to pull the engine but I really don't want to. I can't find anybody who has had a cracked exhaust channel in their bell housing on the Internet anywhere and I would like to "exhaust" all other options prior to pulling the engine. Any and all ideas will be greatly appreciated. Thanks in advance, CONFUSED.

 

[southkogs]

Welcome aboard Sax:

That metal plate is (by the diagrams) the exhaust baffle. I've never really seen what it looks like under there, but maybe you messed that plate up when the engine dropped. It looks as though it's held on by a single screw.

Along with that - if you're running the engine with the drive tilted up, the ball gears can make an awful racket. Just want to make sure you're not confusing that noise.

Is this a new-to-you boat, or have you been runnin' it for a while?

 

[Howard Sterndrive]

you can take that tin plate off and toss it. I'm not sure it serves any serious purpose except to keep one's fingers out of ring gear if reaching under engine or something, but you'd have to have 10 foot arms.