Leaking exhaust manifold on force 150hp

[panther150]

I have a 1991 force 150hp outboard motor that leaks water from the exhaust manifold about every 3 to 4 years. I hear that these motors are known for leaking manifolds. Is there a special thing I can do to repair it this time so that it will last longer? Also, I had to rebuild the motor about 5 years ago because the crankshaft broke at the flywheel when I went to start it(nothing was wrong inside the engine). Perhaps a flaw in the neck of the crankshaft. I have been fearful of this type of thing happening again and in fact feel uncomfortable in taking off the flywheel, fearing that I might damage the shaft (it takes a fair amount of pressure to pull off the flywheel). The last time I pulled off the flywheel, a small piece (chip) of the crank came off where the flywheel makes contact with the shaft. Is my fear justifyed in another broken shaft on this engine while out in the middle of no where?

[imported_LakeRunner]

Fear not, most likely that small chip was the flywheel key. (FEAR) False Evidence Appearing Real

[panther150]

No, it was not the pin, it was a small piece of the flywheel.

[hsc]

I have a 1991 force 150hp outboard motor that leaks water from the exhaust manifold about every 3 to 4 years. I hear that these motors are known for leaking manifolds. Is there a special thing I can do to repair it this time so that it will last longer? Also, I had to rebuild the motor about 5 years ago because the crankshaft broke at the flywheel when I went to start it(nothing was wrong inside the engine). Perhaps a flaw in the neck of the crankshaft. I have been fearful of this type of thing happening again and in fact feel uncomfortable in taking off the flywheel, fearing that I might damage the shaft (it takes a fair amount of pressure to pull off the flywheel). The last time I pulled off the flywheel, a small piece (chip) of the crank came off where the flywheel makes contact with the shaft. Is my fear justifyed in another broken shaft on this engine while out in the middle of no where?

Hello, I have also this problem with my force 150hp every 9 years. Probably I use my boat not so often. I orderd 3 new gaskets and in the next few days I will built the parts together. And here is my question or an idea (perhaps to late after 4 years, but perhaps someone can help me). There are 2 oder 3 1/4-threads (now I am at home and not near by the boat) on the left side of the manifold wich are unused. In the cover there are no holes at this place but in the manifold-System. May I drill those new holes in the manifold-cover to use them with 1/4-Screws for better tightness?
Thx from germany and excuse me for my little experience of american language.
hsc