Winterize Your Mercruiser
Winterize your Mercruiser to prevent damage during the cold season.
Contents
Steps
- Read your engine's owner's manual and all safety precautions. Most owner's manuals have step-by-step winterization instructions.
- Find any missing manual online at Stern Drive Manuals.
- Plan ahead and be aware that your engine has dangerous moving parts.
- Perform a good tune-up to ensure the engine is running OK. Engine problems become worse while the engine sits.
- Haul the boat out and clean the running gear, hull and sides.
- Remove your hull drain plug while stored on land.
- Run your engine on the garden hose with a good flushette to flush out any old salt water that might be sitting in the block and exhaust. Some owners prefer to run the engine on a 50:50 solution of antifreeze, using a hose and a bucket (above the level of the engine).
- Add fuel stabilizer to your fuel tank and run the engine long enough to allow the stabilizer to get into the engine's fuel system.
- Follow the directions for winterization and fuel stabilization in your engine owner's manual. Some people prefer to "fog" the engine. With the engine running at a high idle (with a water hose hooked up for cooling of course), slowly pour a quart of Marvel Mystery Oil down the throat of the carburetor. The engine will try to stall so rev the engine as not to let it stall just until your can of Marvel Mystery Oil is empty. Drop the RPM while you pour the last bit in faster, so as to cause the engine to stall. This will coat the inside valves and cylinder walls.
- Locate all your engine's water drain plugs and hoses. For stern drive and inboard engines such as Mercruiser models the drain plugs are either brass or plastic.
- Remove the drain plugs located on either side of the engine block.
- Make sure that when you remove the drain plug that the water drains and that the passage is not plugged with rust.
- Remove the drain plugs from the bottom of each exhaust manifold and make sure the passages are not plugged or clogged. Some models have drain plugs on either side of the exhaust elbow. Remove the plugs and make sure the passages drain.
- Save all your drain plugs in a safe place for spring.
- Unclamp and remove the large fat water hose from the front of your motor. This will allow more of the blocked passages to drain.
- Remove any standing water from all hoses.
- Remove any water from any oil coolers or power steering coolers.
- Remove your propeller.
- Drain your gear lube and fill your drive with the correct lube (see WikiHow how to Change your Mercruiser Gear Lube). Some owners prefer to either lock or remove their stern drive unit. Many owners remove the boats battery and place on trickle charge over the winter in a safe ventilated area.
Tips
- Save your plugs in a safe obvious location for the spring.
- Use factory recommended oils, lubes, grease and parts.
- Newer motors usually have blue plastic wingnut plugs.
- If you have a speedometer, disconnect the tubing from the back of the speedometer and blow out the tubing with compressed air. If plugged back at the transom find out why and clear the plug.
- Keep your boat clean.
- Always think safety first!
- Removing the drive is more work but it gives you a chance to inspect and service the bellows, gimbal bearing and engine alignment. Drive gasket sets and the engine alignment tool can be purchased online or from a quality boating retailer.
- Repair and/or replace any corroded wire butt connectors such as the connectors to the bilge pump(s) and auto bilge switches.
- Fogging with Marvel Mystery Oil reduces the chance of damage from water or rust while sitting.
- Now is the best time to clean-up, prime and paint any rusted areas.
- Perform a complete tune-up before storing the boat.
- Bad exhaust can leak water back into the engines valves and cylinders. This can cause the engine to rust and lock-up over the winter period. If you suspect that your exhaust is bad and possibly leaking water back into the motor have the problem repaired before storing the boat.
- Older motors usually have brass drain plugs. Some are brass wingnuts.
- The drain passages often plug with rust or mud. Use a small screwdriver to pick out the debris until the passage is clear.
Warnings
- Gasoline fumes will explode and will cause damage, injury or death.
- Follow all safety tips in your owners manual.
- Stay away from all moving parts.
- Fluids and chemicals can cause damage, injury or death. Always follow the directions on the product's label.
- Work in a well ventilated area.
- Remove the prop before running the motor. A spinning prop can cause damage, injury or death. Kids love to play near the prop of your boat so use extreme caution.
- Read your owner's manual.
- Use common sense!
