[Rob Abbott wrote this article in November 2002. I have just moved it here from the old KLRA website. Greig]
Environmental Enhancements For The Older Outboard
Rob Abbott November, 2002
The following is intended for primarily for those with older, say pre-disco era, 2 cycle outboards. I assume you all know that replacing it with a good set of oars or a new 4 cycle outboard is probably the preferred option, environmentally speaking, but for many, not practical economically. So, assuming your motor is old, but you don't want to replace it, here are some suggestions for reducing its emissions. Be forewarned, however, I'm not a mechanic, and some of the following suggestions are contrary to manufacturers' recommendations.
Getting a Bang for Your Buck
Every time a motor fails to ignite a charge of fuel, besides the loss of power, the unburned fuel gets dumped right into the lake. Therefore, a properly tuned engine is important. As a minimum, replace the spark plugs. Make sure you get the right ones as many have been discontinued and replaced by ones with a different number. You may pay a few extra bucks, but I highly recommend you buy from a proper marine dealer. The risk of putting in the wrong ones at one of the chain mega-marts is too high. Make sure, however, you have the model and serial number of your motor; "a black 9.8 Mercury" isn't enough.
However, spark plugs alone are not necessarily enough to ensure proper performance. In some cases, there are carburetor, timing, synchronization, and adjustments, coil replacement and de-carbonizing, required. While all this can be a do-it-yourself job, it is very easy to screw-it-up (I speak from personal experience). Seriously consider paying a professional to do it properly.
Navy Seals
As the Canadian Navy learned with their old submarines, it's important not to have any leaks. In the case of an outboard motor, not only to keep the water out, but also to prevent what's inside from leaking out into the lake. There are a number of seals in the lower unit necessary to keep the gear oil on the inside and the water on the outside. Again, replacing these can be another DIY job, but better left to the pros. While the seals are being replaced, make sure to replace the water pump impeller too.
Take a close look at your fuel line hose. Fuel leaking around the connector or into the bilge of the boat usually ends up in the lake. There are usually little "O" ring seals in the end of the connector that probably need replacement. Replacement "O" rings are probably about $1, but speaking from experience, trying to remove and replace them can be quite a frustrating exercise. Chances are, the rubber fuel line is either hard and brittle, or soft and spongy. Either way, it needs to be replaced. You might consider replacing the whole fuel line and connector. Also check the rubber fuel lines under the motor's hood. I think the alcohol added to modern fuels is the culprit, but if these are hard too, replace them.
Low Cholesterol Diet
Oil added to a 2-stroke engine does not get burned. Consequently, every litre of oil added to your gas tank ends up in the lake. Chances are, your motor's manufacturer specifies a gas:oil mix ratio of 50:1, or in some older models, 24:1. Consider switching to specialty synthetic oil and reducing the oil added to 1 part oil to 100 parts gas (100:1). It is very important that only special oil designed for this 100:1 mix be used. The only brand I'm aware of is AMSOIL 100:1 synthetic. It's not available everywhere and about double the price of regular 2-stroke oil, but you only use half (or in my case a quarter) as much.
Please note that reducing the amount of oil is contrary to every manufacturers' recommendation. I'm a member of the Antique Outboard Motor Club and this is a hotly debated issue, with strong opinions and technical arguments for and against. Personally, I've been on both sides of the fence, but currently a convert to the 100:1 solution. I can only offer that I've run about 25 gallons of this 100:1 mix through my 1957 Evinrude "Big Twin", without any problem. I also know a number of other converts and, to date, I've never heard of anyone having a problem. The only impact I've noticed is the elimination of the blue plume. I also use this mix in my snowblower and chainsaw, which saves having different containers with different mix ratios, another bonus.
Go Green
If you're reluctant to risk the low-oil diet, you might consider switching to the biodegradable oil. Shell has done an effective marketing job touting their brand of this oil, but don't confuse it with the almost identically packaged regular "Nautilus" brand; only the stuff with biodegradable in small letter across the front and the Eco-Logo label is biodegradable. Unfortunately, I haven't been able to find the biodegradable Shell oil anywhere in Ontario. However, I suspect there are other brands; Dennes, carries an Evinrude line of biodegradable oil.
What Kind of Fuel am I?
Okay, this is more a technical than environmental issue, but since engineers designed your motor, gasoline has been reformulated. The chemical details of it I don't begin to understand, but if you're buying gasoline, you want a mid-grade octane rating. Also, because of reformulation, it has a much shorter shelf life. Unless you plan to use that gas within 2 weeks, add some gasoline stabilizer to it. These suggestions also apply to your lawnmower, chainsaw and other small motors. I've known a number of people that have burned out a piston using "last year's" gas.
Dam the Dribble
Most newer motors recirculate any gas and oil that got condensed in the crankcase back to the carburetor or tank. However, if your motor was designed in the days when gas was bought in gallons for 40ยข, it likely has a purge or bleeder system that dumps this to the lake. Depending on the motor, it may be possible to divert this back through a hose to the gas tank, or a separate fuel container. In the case of my aforementioned Big Twin, it was a relatively simple matter of removing a small cover plate, plugging a little hole with a bit of epoxy, drilling and epoxying a tube to the cover plate, and running a hose from the tube back to a gas container. Periodically I pour the collected fuel back into the tank. However, your motor may be more difficult and require the removal and modification of the engine block. Clearly this is only a job for an avid amateur willing to risk irreversible damage to the motor, or a professional.
As I said at the outset, I'm not a qualified professional, more of an amateur dabbler, but if you have any questions or comments fell free to contact me at 905 278 9957, or rob.abbott@sympatico.ca