Buzz
Prepare your Mercruiser for winter to avoid cold weather damage.
Key Steps
Refer to your engine's manual and adhere to safety instructions meticulously.
If your manual is missing, search for it online at Stern Drive Manuals.
Anticipate and acknowledge the presence of hazardous moving components within your engine.
Conduct a thorough tune-up to ensure optimal engine performance. Engine issues tend to exacerbate when the engine remains inactive.
Remove the boat from the water and meticulously clean the propulsion system, hull, and sides.
Ensure your hull's drainage plug is removed when the boat is stored on land.
Flush your engine with a robust flushette or a 50:50 antifreeze solution to expel any residual saltwater from the engine block and exhaust system. Some owners prefer utilizing a hose and bucket setup (elevated above the engine) for this process.
Introduce fuel stabilizer into the fuel tank and run the engine sufficiently to ensure the stabilizer permeates the engine's fuel system.
Adhere to the winterization and fuel stabilization guidelines outlined in your engine owner's manual. Some individuals opt to 'fog' the engine. With the engine operating at a high idle (with a water hose connected for cooling), gradually pour a quart of Marvel Mystery Oil into the carburetor. The engine may attempt to stall, so increase the engine speed to prevent stalling until all the Marvel Mystery Oil is dispensed. Reduce the RPM while pouring the remaining oil to induce engine stall, effectively coating the internal valves and cylinder walls.
Identify all water drain plugs and hoses associated with your engine. For stern drive and inboard engines like Mercruiser models, drain plugs are typically brass or plastic.
Detach the drain plugs positioned on both sides of the engine block.
Ensure proper drainage and check for any blockages such as rust when removing the drain plug.
Extract the drain plugs located beneath each exhaust manifold and ensure the passages are clear of obstructions. Some models may feature drain plugs on either side of the exhaust elbow. Remove these plugs and confirm proper drainage.
Securely store all drain plugs in a designated location for retrieval in spring.
Release and detach the large water hose located at the front of your engine. This facilitates drainage of additional blocked passages.
Eliminate any residual water from all hoses.
Drain any water present in oil coolers or power steering coolers.
Detach your propeller.
Empty the gear lube and refill your drive with the appropriate lubricant (refer to Mytour's guide on Changing your Mercruiser Gear Lube). Some owners choose to secure or remove their stern drive unit. Additionally, many owners remove the boat's battery and store it on trickle charge throughout the winter in a well-ventilated area.
Helpful Tips
- Store your plugs in an easily visible location for retrieval in spring.
- Utilize factory-recommended oils, lubricants, grease, and parts.
- Newer motors often feature blue plastic wingnut plugs.
Important Warnings
- Gasoline vapors are highly combustible and can lead to severe damage, injury, or even death.
- Adhere to all safety guidelines outlined in your owner's manual.
- Avoid contact with any moving components.
- Exercise caution with fluids and chemicals, as they can cause harm. Always follow the instructions on the product labels.
- Work in a properly ventilated environment.
- Familiarize yourself with the contents of your owner's manual.
- Remove the propeller before starting the engine. A rotating propeller can cause damage, injury, or fatalities. Children are often drawn to the propeller area, so exercise extreme caution.
- Apply common sense at all times!
