Broken exhaust elbow bolts!

[MExcelsior]

I just purchased my new-to-me 310 2007 da with twin 6.2 mpi! I noticed before shrink wrapping today that 3 out of four of my elbows had a busted bolt! Is this serious and what would you recommend? (No water intrusion..... Yet!

[northern]

You have the winter to fix them.
I assume by elbows you mean the risers on the manifolds. If so:
The torque on my bolts is 33 pounds. No idea what yours is. But to break them some one probably put too much force on them.
If it was my boat I would remove the elbows, if they look OK take them to a rad shop and get them cleaned. I would also take off all heat exchangers and get the rad shop to clean, inspect and repair them also.
As to bolts if you can grab them with vice grips you may be able to remove them, before removing them spray them with a rust removing solvent to help loosen any rust on the threads.

[Happy Hour IV]

Replace all bolts with studs. This will provide a more even torque, greater torque capacity, easier assembly and much easier removal in the future.