Checking the exhaust on your boat is like checking the air in your car tires. You have to have water coming out of your exhaust for your engine to run smoothly. A lack of water will cause hoses to swell and the engine to get hot or overheat.
For engines with transmission fluid, a quarterly check, or more if used often, is recommended prevention. For hydraulic transmissions, start by running the engine for a few minutes and then shut it down.
When working on your engine or taking apart another system, always use the right tool for the right job. Taking proper care of your hardware will allow reuse, will ensure proper torque, and won't round off the heads or tool attachment points.