America's Definitive Marine Engine Magazine
by Binnie Smith
Most boat owners simply don't have the time or the inclination to decommission their boats' engines. So they do the sensible thing and have it done by a professional. But an owner who knows just what things should be done and whether or not they've been done right is way ahead of the game. With that in mind, here are some basic guidelines to help you make sure that the entire job gets done - and done well.
The fuel tank should be topped off to prevent water accumulation. Otherwise, when the outdoor temperature changes, the fuel will expand and contract, which will draw ambient air into the tank. Water in this air will condense on the tank's sides. But that won't happen if the tank is full.
The fuel should be stabilized. This means dosing the gas with a specific amount of an additive that prevents gelling. Without stabilizer, the lighter gasoline molecules evaporate, leaving gum and varnish behind. It's true that many boat owners get by without treating their fuel. They'll tell you as much, implying that you're foolish to spend extra money for additives. What they don't realize is that gumming doesn't always stand up and smack you between the eyes the first year. Although this can happen, the damage is usually cumulative. Little by little, gum forms in the fuel tanks and carburetor passages. Then one sunny day the engine either won't start, or it simply dies in its tracks.
Most of the time a simple rebuild can resurrect a plugged carburetor. But every now and then you'll be faced with having to buy a new one outright. Either way, get out your checkbook. That's not the end of it, however. Once the carburetor is back on line, you can bet your anchor rode that there's still a bunch of gum and varnish lying in wait on the bottom of the fuel tank, poised to break loose and plug the fuel filter or redeposit itself throughout the newly spic-and-span carburetor.
The lesson is twofold: Ignore the words of wisdom from the character in the next slip and have your gasoline stabilized. If you ever are stung by stale fuel, immediately retrofit a single, or dual, parallel-plumbed fuel filter to capture any gum that migrates out of the fuel tank. Don't settle for half measures. Insist on the big, quart-size filter element you see installed on 30-foot-and-above rigs.
Back to the beginning: When your mechanic treats the gasoline, whether it's at your prompting or on his own, the exact volume of stabilizer required will depend on how many gallons of gasoline your tank holds and on how many months your boat will be out of action. A simple formula on the stabilizer's label will detail the process. If the mechanic doesn't inquire about the length of time the boat will be laid up, he probably doesn't care. Also, the gasoline should be dosed before topping off to better distribute the additive.
If you have a stern drive or outboard motor, have your shop drain the lower unit. The oil should not be changed in the fall, but it should be drained, because any water trapped in the lower unit will freeze and expand, which could crack the housing. Even if the temperature never drops below freezing, the water will rust the gears and machined shaft surfaces.
Moreover, should the mechanic discover water in the lower unit, he can schedule a repair during the winter months - when repair work is slow and you can often negotiate a better hourly rate. Plus, spotting the gremlin before the leaky seal lets in too much water will prevent a surprise replacement of the gearset and prop shaft.
Mechanics refill a gear case through the bottom plug. This is to prevent air bubbles entering the cavity and reducing the volume of oil available to lubricate the gears and bearings. If you spot a trickle of oil emanating from the bottom drain plug shortly after servicing, you should suspect one of two things: It wasn't tightened, or a mechanic carelessly placed two washers on one plug. It happens more often than you'd think.
Stern drives and outboard motors that are run in salt water should be flushed with fresh water for 10 to 15 minutes in order to more completely eliminate saltwater condensation. Less time than that will leave stubbornly imbeded salt crystals in nooks and crannies where they will wreak havoc. In northern climes fresh water is chased with an antifreeze solution, so no water will be trapped and then freeze, expand and crack the head, cylinder block or exhaust manifolds.
On closed-cooling-system inboards and stern drives, your mechanic needs to know the last time the coolant was changed. Over time, coolant loses its ability to fight corrosion. As this happens, an engine will begin to rust from the inside out. A lawfully operating shop will recycle the old antifreeze and replace it with revitalized liquid.
On stern drive and inboard engines and on four-stroke outboard motors, have the oil and filter changed now, not next spring. Most savvy operators drain crankcase oil when it's hot, because that's when the greatest volume of impurities will drain away with the spent crankcase oil. Change the oil in the fall, because this will prevent naturally occurring acids in old oil from eating away crankshaft journals, bearings and piston rings over the winter.
To maximize efficiency during layup, most shops change oil immediately after flushing the cooling system. Tip: If you want to know how competent the technician is, pull the dipstick and see how close the crankcase oil level is to the full mark. If it misses the mark by half a quart or more, the mechanic is either sloppy or doesn't give a damn.
It's critical that cylinder walls, rings and other internal parts are protected against rust by fogging oil. Just as it will in a fuel tank, condensation will form inside the engine. Without a protective oil barrier, crankshaft journals, connecting rods, rod bearings, main bearings and reed valves will rust. When I worked as a marine mechanic, we could spot those engines that had gone unprotected. They were the ones with a connecting rod jammed through the side of the crankcase.
The best mechanics fog an engine in two steps. First they remove all the spark plugs and shoot a goodly quantity of fogging oil into each cylinder before cranking the engine through several revolutions to spread the oil all about. Next, with the engine cranking, they shoot fogging oil down the throttle bore to protect reed valves or intake valves.
Some savvy outboard mechanics shoot fogging oil down the carburetor throat with the engine running at a fast idle. They do this by first shutting off the fuel to the engine. Just before the carburetor bowl is about to run dry, engine speed climbs. At that precise instant they furiously pump in the fogging oil, using the intake pulses to better draw in and circulate the oil. Fogging continues until the engine stalls, or for a maximum of 15 seconds. This last method not only protects the cylinder bore against rust, it also protects the carburetor by virtually emptying it of gasoline. Even so, whenever I fog an engine this way, I still make sure that it's treated fuel that's flowing into the carburetor before I shut off the connection.
Few mechanics will admit it, but some of them aren't patient enough to actually take the time to grease the zerk fittings on outboard motor transom brackets and stern drive and outboard steering tubes. Unfortunately, cutting corners poses a problem. Trapped water that would have otherwise been expelled by fresh grease can freeze and break the housing. At the least, it will induce rust.
Double-check a mechanic's work with your own grease gun. Even if there's the look of fresh grease on a fitting, the job may not have been done right. The technician may have been in a hurry and only pumped in a token shot of grease. That's simply not sufficient. So pump a single shot of grease into one or more fittings. Clean grease should ooze out. Dirty grease means you were shortchanged. Also, if the zerk fittings are covered with a blend of filth and new grease, the mechanic failed to first wipe the fitting clean. As a result, he carelessly introduced marine-grade grease and grit. Problems will follow. If you find only old, dirty grease, it's likely that no lubrication occurred. To find all the fittings on your engine and/or drive, buy a service manual from the engine's manufacturer.
Most marinas remove propellers from stern-drive and outboard boats during the winter. This is for two reasons: The first is to check the prop shaft for damage and fishing line that may have wrapped around the propeller shaft, endangering the gear case seal. The second is that periodic removal of a propeller insures that when you actually must replace it, corrosion won't have welded it to the shaft. That's why propeller shaft splines should be greased annually.
If your mechanic suggests that hoses and/or drive belts need replacing, take a look at the units in question while they're still on the engine. This is one test of your mechanic's honesty. Squeeze the belts. A healthy hose will feel supple. A hard and unyielding hose will be prone to cracking and breaking. Similarly, drive belts should not be frayed or checkered. If you don't know what a new hose ought to feel like, or what a new belt ought to look like, march out to the dealer's showroom and climb under a new boat's engine cover. Squeeze those hoses and look at those drive belts and memorize what healthy looks and feels like.
Make sure the battery is trickle-charged at regular intervals all winter long. Do it yourself at home or have the marina store the battery and top it off. Charging about once a month should be sufficient.
Finally, a competent mechanic should carefully inspect your engine while performing the aforementioned tasks. If an anti-corrosion brick has been eaten away sufficiently to reduce its effectiveness, he should spot it and replace it. Loose bolts and nuts should be tightened, and leaking gaskets should be noted. Always meet with the mechanic who did the work and schedule any necessary repairs now. That way you'll be aware of what needs to be done and you'll have an opportunity to schedule work so your boat can be launched worry-free in the spring.
Tim Banse is a factory-trained mechanic who has been a marina service manager and has written many books on gas engines.