How To Keep Small Engines Humming

Few things are as aggravating as motors that won’t start. Electrical motors are fine, they either work or not. It is dysfunctional gasoline engines that drive me to distraction.

There are a host of things that can go wrong with gasoline motors and almost invariably they do. Issues range from faulty battery connections to contaminated fuel lines, inadequate spark and all too frequently the full range of other imponderables. Even an engine that finally consents to run but will only do so haltingly under protest severely aggravates my generally compliant nature.

In the “old” days the remedy was straightforward — off to the repair shop. Now, with shop rates posted at anywhere from $80 to $100 an hour, professional repair has taken on a complexity I have yet to accept as inevitable. The question rapidly becomes whether it should be repair or replacement recognizing that no matter how much we spend on refurbishing the machine is in fact worth no more coming out than it was going in if resale value is a measure of worth. The further recognition is that even if one part is new all other parts are not and function failure is only a matter of indefinite time.

We own two mowers, a ride-on and push kind. For the numbers of hours they are in use they should eventually be handed down to the next generation but they will not. By and large the less expensive ($2,000 range) ride-on models are seemingly not destined to survive more than nominal use for relatively few years. In our circumstances, a four-or five-year unit used to be an old machine, its depreciation cost significant enough to give pause to the entire concept of cutting grass at all.

But we found a mower’s engine life can be extended considerably with a touch of judicious care. Now it is not likely the motor but other failures that will finally signal the end of these machines as functional units.


Our improvement in expected longevity is the use of a gasoline additive and, separately, a starting aid. I’m confident there are legions of folks from casual operators to scholarly small engine repair instructors who may disparage my methods but it is not my intention to debate or defend. I am merely outlining what works for us.

I was persuaded unleaded gasoline was too dry for these motors, significantly inhibiting engine performance. This may not be new information, but it was new to me. Accordingly, to every gallon of gasoline we now add one ounce of automatic engine transmission oil (the red stuff). With this additive every aspect of engine operation is quite remarkably, almost visibly, improved. A puff of smoke upon firing but nothing visible in operation, almost a quantum leap forward in previously accustomed performance.


A mower battery is too small to be relied upon for extensive cranking and rather than keep turning a cold engine until the cycle grinds to a halt we inject one second (no more) of aerosol ether directly into the air filter. The intent is to use it only as an initial firing aid, nothing more. Ether should be handled only by adults conversant with its inherently explosive potential in an open air circulation environment.

We have found an electric battery charger to be of excellent use in topping up power before starting. A five-minute connection is sufficient and if there is any shortfall in natural recharging this process readily replaces such deficiency.

Battery water levels should be checked at least every few months. We use distilled water squirted from a 10-cc syringe. I would add the caution that batteries should be refilled with extreme care. Eye and skin protection is paramount. It takes a lot less time to don suitable protective gear than it does to remedy an acid accident.

We find it constructive to change spark plugs each season whether it seems necessary or not. In our experience a reliable spark greatly enhances engine efficiency and for less than $10 is well worth doing.

Should power transmission seem to be slipping, try changing the drive belt before getting too excited about buying a new machine. It can readily be done at home for about $35.

Wheel bearings should be serviced via grease gun and tires checked for pressure. Low pressure is readily determined by the simple expedient of pressing down on each tire to see if it has the same resiliency as its off-side mate. If they are all flat that too will be apparent soon enough.

Cutting deck pulley shafts should be oiled at least once a season. Failure to do so may result in blades failing to turn upon engagement and a major overhaul may be required. Decks are easily removed from your standard retail mowers, perhaps a dozen or so slide in clips holding various components in place. The trick is to remember which part fits where when resetting the deck, but a bit of concentration will soon show where logical connections need to be made if memory has failed. Simply drop the deck to its lowest cutting level and begin pulling cotter pins.

While the deck is out, it is advisable to check its belt as well. Signs of wear will show failure cracks and shiny spots where the belt has been slipping. If in doubt replace. It’s cheap insurance. For the novice it’s best to draw a chart showing the routing of the existing belt before dismantling so there are no later realignment errors.


We have found the best oil to use for lubricating bearings and shafts is not the usual 10w/30 or equivalent but chainsaw bar oil. This oil seems to be more efficient requiring less frequent applications. We use summer grade which is quite viscous but flows well enough to assure penetration. There may well be reasons why this should not be done but so far no negatives have become apparent in our use of this product for this purpose.

If your mower is cutting unevenly drop your deck down to its lowest point on a level surface and adjust the two vertical settings, one on each side, until base clearance is equalized. A simple bolt mechanism rides up and down and is adjusted by turning a (usually) nine-sixteenth nut.

Remember to keep your blades sharp. Good-quality blades will actually wear at the ends before giving up their cutting edges. If you see an uncut centre strip on your lawn with each pass you need new blades If you hear a rock trying to dodge your blades resharpen at once. You will have a large burr on the cutting edge no longer effective for the job. And do clean the underside of the deck of accumulated debris. A three-inch metal paint scraper works well.

We never use a pickup bag. We find clippings do considerably more good on our lawn than in a landfill as moisture-retaining fibre, roots shade and eventually fertilizer.

Four years ago we decided we needed a new ride-on mower and may yet be obliged to make that purchase but as long as our revitalized old one continues to start and run well clearly our incentive to part with another couple of thousand bucks for no discernible purpose just isn’t there.

StanHarderisaretiredangusrancherbased atSt.Brides,Alta.Contacthimat [email protected]

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