Toolshed: Overwintering Engines

BY ROGER B. SWAIN

Plants aren’t the only entities that can fail to survive a winter. Bad things can happen to machinery as well. Purists will point out that engines are inanimate, but an engine that won’t start up in the spring is, for all practical purposes, dead. Spring is a season when so much is growing, and growing so fast, that none of us has the time or the patience for garden tools that aren’t ready when we need them. Fortunately, the unnecessary expense of buying a replacement lawn mower, or taking the tiller in for repairs, can be obviated by a few preventative steps at the end of each gardening season. How long the off season lasts depends on where you garden, but any time a machine is to be inactive for three months or more it should be put away with a certain amount of special care. That way it’ll be ready when you are.

Here in New England, it’s the end of October before my wife Elisabeth and I pick a warm sunny day to put to bed the dozen or so pieces of outdoor power equipment that we’ve come to depend upon. There’s our garden tractor, followed by two walk-behind rotary mowers, three tillers, the fruit tree tank sprayer, the chain saw, two string trimmers, a leaf shredder, and a water pump.

The last two are powered by electricity. All the others are powered by gasoline, and gasoline is their weakness. Left in an engine for the winter, the fuel will go bad, rendering the engine unstartable. At my local small-engine repair shop, they tell me that gasoline is now fresh only for a month. One solution is to run the engine until the gas tank is empty. In the best of all possible worlds, every rotary mower would sputter and quit just as the last blade of grass was cut. In reality, it is easier to treat the fuel with a gasoline stabilizer, an inexpensive additive available at any hardware store. While some people wait until fall to treat the remaining gasoline in engines, we add stabilizer to all our fuel the same day we buy it.

That way no one needs to remember which engine has been treated and which hasn’t.

Periodic oil changes are almost as important a factor in ensuring an engine’s long life. This is only necessary for four-cycle engines; two-cycles burn a mixture of oil and gas. Heavily used machines need more frequent oil changes, but every engine’s oil should be changed at least once a year. The first step is to disconnect the spark plug. Then if you don’t know, or can’t find, the location of the oil drain plug, check the engine manual. Warm oil drains best, so when you have shut the engine off for the last time, drain out the oil before it has a chance to cool and thicken. A plastic oil pan, obtainable at any auto parts store, is the best container for catching the draining oil. Once the engine oil has finished dripping, screw the drain plug back in again and refill the engine with fresh clean oil of the specified viscosity (usually SAE 10W-40 or 10W-30) to the fill level. A small funnel will help ensure a spill-free transfer, but a rag should be on hand just in case. As for the old oil, funnel it into the empty containers and deliver it to a local garage or other recycling center.

The air filter should be cleaned next. Most small gasoline engines use a sponge foam element to filter out dirt. Others have a paper filter. Our tractor has a sponge element over a paper filter. The paper filter can be blown clean or replaced. The foam elements are harder to clean, since they trap dirt in a layer of oil. Hot soapy water is the recommended cleaning solvent. Don’t use gasoline; it contains the carcinogen benzene. Charcoal lighter fluid is safer, but it must be used outdoors and away from any flame. The clean foam element filters must then be reoiled with a tablespoon or so of motor oil squeezed to distribute it uniformly, and then reinstalled.

Elisabeth is not only in charge of the air filters; she is also a particularly determined cleaner of the engine’s exterior, going after all the grime that accumulates, especially on the engine’s cooling fins. Lots of rags and an assortment of small pointy objects enable her to get into the tight places where dirt lodges.

Where there is an oil- or grease-filled transmission, the level of lubricant should be checked. Replacement is seldom, if ever, needed. All the grease joints, however—those little metal nipples called zerks—should be lubricated with a grease gun. All the other places where metal rubs on metal will also benefit from a squirt of oil.

The next job is to set about removing all the accumulated detritus—the grass from under the mower deck, the earth from the tiller tines, the stems wrapped around axles, the dead leaves caught beneath protective shields. This involves a certain amount of unscrewing and unbolting, so that you can get to where the rubbish is hiding. A screwdriver, putty knife, and wire brush all come in handy. Invariably you will find places where the paint has peeled or been rubbed off, leaving bare metal. A squirt of WD-40 or other spray lubricant will keep the metal protected from moisture over the winter.

All water pumps will need to be thoroughly drained if they are to be stored in a below-freezing location. Our fruit sprayer pump is difficult to drain, so instead I add a gallon of automotive antifreeze, which contains rust inhibitor, and run the engine to circulate it through the hoses, pump, and tank before putting the sprayer away for the winter.

This is also a good time to sharpen blades, replace worn tiller tines, check belts for wear, and pump up pneumatic tires (though they will have to be checked again come spring).

Though it may seem odd, it is also good practice to unscrew the spark plug when the engine is cool and pour a teaspoon of motor oil directly into the hole. With the spark plug still disconnected, crank the engine several times to distribute the oil. This will create a small amount of white smoke upon first starting the engine next spring, but it will keep the cylinder protected. Reconnect the spark plug, or next spring you’ll wonder how all your preparations could possibly have resulted in an engine that won’t start. We’ve been there.

Finally, give some thought to where the unused machines are stored. Ours get parked upstairs on the main barn floor where they are safely away from winter’s road salt and wetness. Cold is fine, but the location should be dry. Like a well-weeded, well-watered, and well-mulched perennial bed, our machines are ready for dormancy. Knowing that we have treated them well, we expect them to return the favor come spring. H

What’s in gasoline stabilizer?

It is easy to be skeptical of miracle additives, but gasoline stabilizers really do protect engines by protecting the fuel. The problem is that gasoline oxidizes over time. Molecules in the fuel bond with so-called free radicals, creating bigger, sticky molecules. These in turn harden, coating the interior surface of the engine with a varnishlike substance that interferes with fuel flow-in short, producing an engine that no longer runs. All brands of gasoline stabilizer contain antioxidants-substances that bond with the free-radicals and, by this “capturing of the enemy,” slow the normal aging of gasoline. While a gallon of untreated gasoline may go stale in two months, treated fuel can last a year or more. The specific chemicals that individual manufacturers use remain a proprietary secret, but the concept of antioxidant additives is a familiar one. BHA and BHT are both examples of antioxidants routinely added to packaged foods to delay spoilage.

Adding stabilizer to gasoline will not reverse oxidation that has already occurred, hence the advantage of treating fuel as soon as it is purchased. The stabilizer itself will eventually lose potency-two years after opening is a typical shelf life. Some brands change color to indicate the loss of effectiveness. But while they are good, they are very very good. For more information, log onto the web site of one popular brand.

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