Since I bought the 1983 25' Oday last year I have been having trouble starting the 1GM diesel engine. Finally his year the engine woulld not start. Since the engine had never any major work done on it (I have records from previous owners) I feel that it possiblly should be rebuilt. My other alternative is to replace the engine with an outboard Tohatsu/Nissan 9.8. Any ideas or comments?
That Tahatsu outboard is a nice quiet engine. A friend of mine bought one for his Seaward 22 last year and he tried it out this season for the first time. Of course he had an outboard on this boat with a heavy duty outboard bracket, so it was just a matter of clamping it on.
In your case where you don't have a bracket, you would not only need to spring for the engine, but you would also need the bracket plus the fiber block that goes between the bracket and the transom which is shaped for the angles needed for the outboard to be straight in relation to curvature of the stern. Where this boat wasn't built for an outboard on the stern, the strength of the transom may be questionable. The torque from these outboards is strong enough to stove in the transom on an O'Day 25. So this would also need to be checked out and if it needs beefing up, it could be done.
I think that a diesel inboard engine in a sailboat is worth fixing or replacing. If it was a gasoline two stroke Saildrive engine with the fuel tank in the bilge, I'd say go for the Tohatsu outboard and build a vented fuel compartment in the cockpit for a portable 6 gallon tank. I'm not too keen on having gasoline tanks in the bilge of a sailboat, myself.