Mowing down mower problems - lawn mower troubleshooting

Flower & Garden Magazine, April-May, 1993 by Doc Sprockett

Saturday has always been my "mad" day. Whether it's grandchildren or lawn mowers, I can't abide something that doesn't do what I tell it to do. Especially on a Saturday.

One particular morning found me sprawled on the driveway, fiddling with my mower. There is nothing graceful about an old man stretched out before a piece of machinery with what's left of his hair flying every which way. One of my neighbors couldn't help shouting out as he drove by, "Looks like you have everything under control"

The truth was I did have things well in hand. Mower troubleshooting is simply a matter of following a systematic approach. Look for the easiest problems first, then test for more difficult things. With any luck, you'll have the malfunction fixed in no time.

Failure to start is the most common mower problem. First, check the obvious. Is the mower turned to the start position? Is there fresh fuel in the tank? Is the spark plug wire attached firmly to the plug? If the mower doesn't fire up after a couple of tries, move to the next step. Don't keep trying to start the mower; doing so will just frustrate you and flood the engine.

Next, see that the throttle cable is operating properly by moving the throttle into the open position to start the engine. Check by following the throttle cable down from the switch. Observe the throttle movement. Make adjustments as needed.

Be sure you have primed the engine if are starting it cold. If you have been priming quite liberally, you may have flooded the carburetor. Pull the starter cord a few times in the stop position to clear the excess fuel. Take a break, then try again.

Check the safety shut-off switches designed to protect you. Grass catchers must be properly attached and safety shut-off switches held down to start and operate many newer mowers.

If the mower still won't start, inspect the spark plug thoroughly. It is an inexpensive but vital part, so replace it if you suspect any problems. Be sure it is tightly installed. Likewise, replace the spark plug wire if you spot any kinks or damage. Reinstall the wire carefully, ensuring that it is snugly in place.

Also, make sure the air filter is free of debris. The engine needs a steady supply of clean air to operate properly. A clogged air filter can cause the engine to run hot.

Be sure all belts are tightened on belt-drive mowers. As part of regular maintenance on belt-drive mowers, you must periodically adjust the belts to compensate for the slight stretching normal operation causes. Chain drives should maintain adjustment, but they may become dirty and require cleaning.

If the engine starts fine but stops suddenly, the most common problem is a sheared flywheel key. The flywheel key is designed to break when the mower blade hits a hard object. This feature protects the crankshaft and engine components from damage but it also renders the mower inoperable until you replace the flywheel key. You can replace it yourself or take it to a mower repair shop, but before you do, also check the mower blade. It may be bent from the impact. Never use a bent or damaged mower blade.

Check the exhaust pipe for grass or debris blockage. Clean out debris with a dowel or other instrument. Also, check the muffler for rust or damage. A sure sign of a damaged muffler is an extremely noisy engine. Many universal replacement muffler kits are available.

If the mower vibrates excessively as you operate it, stop immediately. Turn off the engine and disconnect the spark plug. While wearing gloves, check the blade for damage or balance. If the blade is out of balance, remove it and use a file to sharpen the heavy side until proper balance is restored. Replace the blade if it is damaged.

Tighten the blade well when you replace it. Check the mower housing and also be sure the engine housing is tightened. Look for any damage or dents. Major deck damage requires professional repair.

If the engine is smoking, it could be bad news or no big deal. Before you start shop-for a new mower, review the carburetor settings. A rich mixture could cause smoking. Adjust the mix to proper proportions. If this doesn't work, seek professional attention.

An overheating engine is I the second most frustrating thing, after a mower that won't start. Most people will kick the mower, get a soda and then start up again after the mower cools a bit. It's better to get to the root cause of the overheating. In most cases, a buildup of grass and debris on the cooling fins and other areas prevents proper air circulation. A good cleaning with soap, water and a little elbow grease could solve the problem.

Just as the engine needs to be clean, the same applies to the engine oil. If I had a dime for every time I told someone to change their oil, I'd be a rich man. Routine maintenance will help prevent many of these little problems.

The problem with my mower that particular Saturday morning was a loose shut-off switch. If I'd tightened it the last time I had the mower on the workbench, I wouldn't have had to sprawl all over the driveway. Even this old dog can learn a lesson.