2. Winterizing Mercury Outboard Motor—Mercury Marine Essential Maintenance

Winterizing Mercury Outboard Motor—Mercury Marine Essential Maintenance

 

It’s that time of year again, and unfortunately, it’s time to store your boat for the season. While it’s always a bit more fun to pull out your boat than to put it away, properly winterizing your Mercury outboard engine avoids engine damage and will facilitate a smooth start to the beginning of next season, especially if there are any telltale signs, for instance, you notice engine oil leaking.

If you’re wondering how to winterize a four stroke outboard boat motor, the same process applies—just be sure to follow the manufacturer’s service manual for stroke-specific steps.

TL;DR: Winterizing your Mercury outboard motor is essential to prevent corrosion, fuel issues, and internal damage. Whether you have a 2-stroke or 4-stroke engine, follow six essential steps: flush the engine, stabilize fuel, fog the motor, change plugs and oil, and disconnect the battery. Learn how to winterize a boat motor the right way to ensure a smooth start next season.

Winterizing a Mercury Outboard Engine: Complete Step-by-Step Guide

This winterization guide is based on recommendations from certified Mercury Marine technicians and official service manuals. Always consult your owner’s manual before performing DIY maintenance.

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While there are several things you can do before storing your boat to get a jump on next season—like changing your oil, changing your fuel-water separating filter, inspecting your internal engine components, and maybe touching up some scratches on your cowling cover—these apply when learning how to winterize a 2 cycle outboard motor properly, especially Mercury models.

1. Thoroughly flush your engine
2. Stabilize your entire fuel system
3. Fog your outboard engine
4. Change your spark plugs
5. Change lower unit engine oil
6. Disconnect your lead acid batteries

Flush Your Engine

You’ll need:

• Motor flusher(tool motor flushing muff)
• Garden hose
• Water supply

It’s important to thoroughly flush your engine to remove any salt buildup if you are a saltwater boater, or general mud and grime if you are a freshwater boater. Failure to remove this debris can cause or contribute to corrosion in the engine. If you’re a saltwater boater, salt crystals in the lower unit can cause a great deal of damage.

If your stroke outboard has a hose adapter, simply screw the hose into the port, turn on the water and let the water run for about 5 minutes.

Next, remove the cowling cover and look for any salt or grime build-up that may have settled outside any engine components. If you spot any build-up, simply rinse it away.

Finally, tilt the engine all the way up, then trim it all of the ways down to make sure every drop of water drains from the engine.

**Caution**

Do not run the engine when flushing while using a hose port. This method is solely designed for flushing while your engine is entirely off.

Flushing Your Outboard with the Engine Running

To flush your late model mercury outboards with the engine running, you will use a motor flusher (also known as earmuffs). Screw your garden hose onto the motor flusher, then slide the motor flusher over the engine’s water intake. You must be sure that the earmuffs are completely covering the water intake. Using this flushing method, you will turn on the engine. But first, make sure that you have a good water supply and that water is coming out on both sides of the earmuffs.

Start the engine and make sure that water is flowing from the tell-tale. Assure that your engine is not overheating by holding your hand under the tell-tale water stream. It should not be uncomfortable to hold your hand in the stream of water. If the water is excessively hot, water is not flowing correctly, and you are overheating your engine—turn off the engine, reposition the earmuffs, and start again.