a) - you didn't seize it. If it was, it wouldn't turn over. Based on our phone calls, I really don't think you've trashed the engine.
b) If the starter was burned out, it wouldn't work at all. Short cranking cycles (5-10 seconds) in succession are better than long cranking. You don't ever want to crank more than maybe 20-30 seconds max, and then that's really too much - risks of causing exhaust water issues on some engines (fill up the water lift and back it up to the exhaust valves), overheating the starter, big tax on batteries etc. All that said though, if your starter still turns, it's still doing it's job.
c) You shouldn't get anything out of the exhaust manifold in the engine compartment if all is connected and not leaking. It should all exit at the end of the exhaust run, which I believe exits the transom on your boat. Do you have the air cleaner on? Are you sure you didn't see something cough back out the intake?
d) I think you might be closer to starting than you think. Black in diesel exhaust often indicates unburned fuel. Any rumbles like it almost is firing? Make sure all your fittings on the fuel side are not leaking, especially if you've removed canister type filter assemblies. Try cracking the banjo fittings on the back of the injectors ever so slightly, have a helper crank a few seconds, and with a rag in place so fuel doesn't run everywhere, see if it weeps out from around the fitting.
Can you provide anymore detail?
b) If the starter was burned out, it wouldn't work at all. Short cranking cycles (5-10 seconds) in succession are better than long cranking. You don't ever want to crank more than maybe 20-30 seconds max, and then that's really too much - risks of causing exhaust water issues on some engines (fill up the water lift and back it up to the exhaust valves), overheating the starter, big tax on batteries etc. All that said though, if your starter still turns, it's still doing it's job.
c) You shouldn't get anything out of the exhaust manifold in the engine compartment if all is connected and not leaking. It should all exit at the end of the exhaust run, which I believe exits the transom on your boat. Do you have the air cleaner on? Are you sure you didn't see something cough back out the intake?
d) I think you might be closer to starting than you think. Black in diesel exhaust often indicates unburned fuel. Any rumbles like it almost is firing? Make sure all your fittings on the fuel side are not leaking, especially if you've removed canister type filter assemblies. Try cracking the banjo fittings on the back of the injectors ever so slightly, have a helper crank a few seconds, and with a rag in place so fuel doesn't run everywhere, see if it weeps out from around the fitting.
Can you provide anymore detail?