Tips For Winterizing Your Motors And Boats

July 6, 2022

By Tim Smalley, Minnesota DNR

Each fall, after the boating season is over, it's time to prepare your watercraft for winter storage. For some, putting the boat away consists of turning it over on the beach, putting the motor in the basement, and forgetting about them until spring.

However, taking a few more steps in the fall will reduce some hassles in the spring when you get ready for your first outing. If you have to stop to fix a cranky motor, or hunt for a life vest without a broken zipper, you'll be cutting into your time on the water.

Here are some tips for winterizing your boat.

Fill Your Gas Tank

Use a fuel stabilizer in your gas tank, especially if your fuel has ethanol. Your state may differ, but all regular gas in Minnesota has ethanol, as does some premium unless it is labeled as non-oxygenated. Leave a little room (5 percent) in the tank for expansion. Ethanol has an affinity for water and can cause other problems, especially in older motors. A stabilizer helps deal with moisture condensation problems, and keeps the gas fresh until spring.

Flush The Cooling System

You can bet at some point during the summer, you ran through the shallow end of the lake and dredged up a good percentage of the lake's bottom sediment plus the usual snips and snails and eelpout tails through the outboard's water pump.

Using an earmuff style flushing attachment that hooks up to the garden hose can help make flushing a quick chore. Water pump impeller fins can break off after a few years and may need replacing, too. This isn't a job for Mr./Ms. Fumble Fingers so you if you aren't sure how to do it, you might want to farm this one out to the professionals.

Check The Plugs, Fog The Cylinders

While you are flushing the motor, it's a good time to take the cover off and check the plugs, plug wires, and fuel lines, and run some engine cleaner through the carb. After this, run the engine with the fuel line disconnected until it stops. This pulls the stabilizer through the system. Inspect the plugs, too, but before you put the plugs back in spray some fogging-oil in each cylinder to help prevent the cylinder walls from rusting. Empty and clean the fuel-filter bowl as well.

Change The Gearcase Lube On Lower Units

Even on new motors, a little water can sneak by the propshaft seal. It then gets into the lower unit and can corrode the gears. And if it's a lot of water, it might cause freeze damage. If the old gear lube oil looks really milky, it's also a telltale sign of imminent seal failure. More than a few drops of water (leaky shaft seal), a large amount of metal filings or gear teeth (grinding gears) in the oil mean a trip to the shop. Unfortunately, there is no gear-tooth fairy, so it will cost money to repair.

Changing gearcase lube can be messy, since you fill it from the lower drain hole. Take out both upper and lower drain screws, let the old stuff drain out in a coffee can, and dispose of it properly. Then force the lube into the bottom hole until it runs out the top one. This is a little easier if you use one of the inexpensive lower unit gearcase lube pumps that you can find at a well-stocked marine dealer. Have some kitty litter around to soak up any spills on the garage floor. Please remove the cat first.

Check For Worn Or Loose Parts

Checking for worn or loose parts includes the steering, which can loosen up over the summer, and also the trim tab on the bottom of the anti-ventilation plate just above the prop. The trim tab, in combination with the steering friction adjuster (sometimes a screw, sometimes a lever) helps fight a kind of boating accident we are seeing more of every year. Folks let go of the steering tiller or wheel while the boat is moving and it is so loose that the boat cuts a hard right due to propeller walk and ejects the operator from the boat. The boat continues around in a circle, running down the person in the water. Thus the name Circle of Death accident.

Check The Prop For Any Bad Dings

Repair or replace the prop as necessary. You can hammer out minor dings with a rawhide mallet, but bigger ones need professional help. Dents and nicks throw off the prop's balance, which can eventually wear out seals and gears. Also check for fishing line around the prop shaft. Remove it to prevent damage to the shaft and seals. Grease any zerk fittings that need it, and finally, store the motor standing up no, not you, the motor should be standing all winter. It doesn't hurt to put a breathable (not plastic) dust cover on them, too.

Non-Motor Items To Examine

Besides the motor, there are other items to check over on your boat before you store it. Check your boat oars for serious cracks and replace as necessary. Check aluminum boat hulls for missing rivets, torn seams, obvious leaks, loose seats, torn up transoms, etc.

Check your boat cushions and life vests, and make sure they aren't torn or otherwise damaged. Also check buckles, zippers, and snaps to be sure they are in working order. If they're damaged, torn or seriously worn, they have to be discarded. You can't sit down at the sewing machine and stitch old flower-power applique.

Originally published October 2, 2014. Tim Smalley is a boating safety specialist with the Minnesota DNR.