I recommend doing your lawnmower maintenance in the fall. Performing many of the tasks included in this tutorial will prevent damage to your mower that might otherwise occur during the cold winter months ahead. In addition, proper fall lawnmower maintenance will ensure that in the spring, when you’ll surely have plenty of outdoor tasks on your to-do list, your mower will start right up.
Before you begin, see if you can locate the instruction manual that came with your lawnmower. If you can’t find it, you’ll want to do an online search for your make and model. You’re gonna need specs for various parts and materials. Any specifications that are different from those suggested in this article should be given precedence.
- Safety goggles
- Bulb baster
- Spark plug socket wrench
- Oil pan or catch basin
- Two cinderblocks
- Squeeze baster
- Wire brush
- Blow drier
- Piece of wood (to keep blade from rotating)
- Putty knife
- Whisk broom
- Torque wrench
- Fuel stabilizer
- New spark plug
- Spark plug feeler gauge
- Lawnmower oil
- New oil filter
- Oil filter wrench
- New (paper) air filter
- Bench grinder or professional blade grinder
- Cone shaped blade balancer
- Metal file
Oh yeah, you’re gonna get dirty, so dress accordingly. One more thing – make sure the engine and the oil have completely cooled before you begin this project.
The first thing you want to do is remove all the gasoline. It’s always nice when you can run the mower down to almost empty on that last autumn mowing. Whatever gas is left in the tank after that needs to come out. You can siphon it, remove the tank and empty it, or tip the mower over and pour it out (into a can or container). A long kitchen bulb baster can help you get the last few drops out. You might want to save the gas for your snow blower; you’ll probably be needing that soon! If not, funnel it into your car if you haven’t added any oil to it (there will be oil in your gas if you have a two-stroke engine). Don’t save it for next year though, the winter cold will cause condensation in your gas container, and you don’t want water in your gasoline.
Now restart the mower and run it till it quits. That’ll get rid of any gas in the engine and the carburetor. Use a blow drier (yup, the kind you’d use on your hair) to really dry out the tank. Then spray the inside of the tank with just a bit of WD-40 to prevent rust.
An alternative to removing all the gas is to add a fuel stabilizer to the fuel tank and run the motor for about 5 minutes. This will disperse the stabilizer throughout the fuel system and prevent fuel from undergoing degradation and oxidation during prolonged winter storage.
Disconnect the spark plug wire and remove the spark plug using a socket wrench. If it’s cracked, just replace it. They’re about two bucks. Check your owner’s manual or go online to find the correct gap for the new plug. Adjust the gap by tapping it gently or by pulling it outward with a flat-head screwdriver. Use your feeler gauge and slide it into the gap. It should fit into the gap with just a slight drag. If the old spark plug isn’t cracked, clean it by dipping the end in a bit of gasoline and lightly going over it with a wire brush. Don’t forget to check the gap.
Clean the spark plug housing (where the spark plug was situated before you removed it) with a rag and put a couple of drops of oil into it. Screw the plug back in with your hand, then give it just a quarter turn with the socket wrench. This next bit is important! Do not re-connect the spark plug wire till you’re ready to use the lawnmower again in the spring. This will prevent the engine from accidentally starting up during the various tasks you’re about to perform.
Before you begin this step, make sure you have the right type of oil for your lawnmower. Once again, refer to the owner’s manual or the internet. If you have a four-stroke engine it will usually be SAE 30. You can get this at your local home improvement store. If you have a two-stroke engine, two-stroke oil should be mixed with the fuel and you can skip this step. You can find two-stroke oil at a gas station. You might be able to find 2-stroke fuel already mixed there, as well. You definitely want to change the oil (on a four stroke) as part of your fall maintenance. This is because old, used oil has all kinds of gunk in it which can harm your lawnmower engine over the winter.
Is your spark plug wire is still disconnected? OK then, now you can clean around the oil fill (where you put the oil in). An old toothbrush works well here. Remove the dipstick, if your mower has one.
Now tip the mower onto its side. You’ll see a bolt under the mower housing just above the blade. This is the oil drain plug. Remove this with a socket wrench. Put the mower up on the cinder blocks and let the oil drain out into an oil pan or catch basin until it stops dripping out of the tank. Remove the cinder blocks and tip the mower again.
Screw the drain plug back on with the socket wrench. Make sure that it’s tight enough so the oil doesn’t drip out, but not so tight that you’ll have a hard time getting it off again next year. You’ll want to check this occasionally during the mowing season as well, to ensure that the vibration of the mower hasn’t loosened it (remember to unhook that spark plug wire).
If your lawn mower has an oil filter, replace it now. It looks like a small cup and you’ll find it right near where the oil drain plug was. Unscrew the oil filter by turning it counterclockwise with an oil filter wrench – just to loosen it. Finish unscrewing the filter by hand and empty its contents into your catch basin. Wipe the pad where the filter was mounted with a rag.
Put a drop of the old oil onto the rubber gasket of the new oil filter. This will create a seal between the oil filter and the engine. Screw the new filter in by hand, then tighten it up a bit with the oil filter wrench.
Now you can set the lawnmower upright and funnel the new oil into the tank. Be sure to use the correct amount of oil – again, check the manual or look online for specifications. If you have a dipstick, add oil only up to the “full” mark . Do not overfill or you could break an oil seal which will cause oil to leak from your engine.
Throughout the mowing season your air filter will begin to get clogged. Not only will this eventually cause starting problems, but your engine simply performs better with a new or clean air filter. So we’ll take care of that next. Your lawnmower will either have a foam or a paper air filter. If yours has a paper filter, you need to replace it. If you have a foam filter, you’re gonna clean it.
Let’s start with the paper filter. Just unscrew the cover and remove the old filter. Place the new filter cartridge into its holder – the pleat faces out. Replace the cover, and you’re done.
If you have a foam filter, unscrew the cover and remove the filter unit. Take out the sponge and wipe the inside of the unit with a clean rag dipped in a bit of kerosene. Next, clean the sponge thoroughly with hot soapy water (dishsoap works just fine). Get out all the oil and any gunk, rinse well and let it dry. Next, soak the sponge in some clean engine oil, then wrap it in a clean rag and squeeze out the excess. The oil helps to keep dirt and grass from getting into the carburetor. When returning the sponge to the filter unit, the lip should stick out over the edge. Kind of like muffin top. Then just screw it back in.
You want sharp, balanced blades because your lawnmower will run more efficiently and your grass will be healthier for having a clean shear.
The spark plug wire’s still disconnected, right? Just checking. Tip the mower back onto its side. OK then, put on your gloves (you can certainly get a nasty cut from your new or sharpened blade, but a dull or jagged blade can do just as much damage) and put a block of wood between the blade and the deck (bottom of the lawnmower) to keep the blade from moving while you’re trying to take it off.
Remove the bolt that secures the blade. If it has rusted tight, spray both the nut and bolt with some penetrating oil and wait a few minutes for it to unfreeze. When you’re able, remove the bolt and then the blade. At this point, take a look at your blade. Is it cracked, bent, really jagged, or badly dented, chipped or nicked? Just get a new blade. Really. A bent or cracked blade could break off while you’re mowing and cause severe injuries. This’ll run you about $10 to $20. Certainly worth it for protection from grave bodily harm. Also, if you don’t have a bench grinder or a blade grinder, just take the blade to most any hardware store and they’ll sharpen and balance the blade for about $10.
Now that the blade has been removed, you want to clean the deck. Use a putty knife to scrape the exposed underside of the mower. Just remove the grass and gunk. Then take the whisk broom and try to get the small stuff off. You can rub with a clean dry rag to get it really clean, but remember, no water here; this will only promote rust.
Next, check the underside of the deck for any loose nuts, bolts – fasteners of any kind. Give ‘em a good twist with a wrench. As well, brush a bit of touch up paint onto any rust spots you see. Once the paint is dry (if you’ve used any) spray the whole underside of the deck with wd-40. This will inhibit rust and help keep grass from sticking when you start to mow again in the spring.
Alrighty then, back to the blade. Safety first – if you’ve removed them, put your gloves back on. Scrape off any grass or gunk that has built up around the hole at the center of the blade. This will keep things nice and tight when the blade is remounted.
You can use a grinding wheel, but you’ll get better results if you have a blade grinder. You want about a 40 degree angle, and really try to keep it consistent along the length of the blade. A thinner angle will work fine at first, but it will get dull and nicked quickly. And a more blunt angle won’t cut as well as you need it to.
First, put on your safety goggles. Move the blade across the grinder, using a back and forth motion. Don’t put too much pressure into it or the metal will get too hot and will no longer be tempered. You might want to have a bucket of water nearby so that you can dunk the blade in it to cool down. If the blade turns kind of a light tannish-gold when you’re grinding it, you can pretty much assume it has lost its temper.
You don’t have to grind till it’s perfect. A few nicks are OK. Just make sure the edge is sharp. And that it’s even (has the same angle) on both sides. If you have a cone shaped blade balancer, place it on a level surface and stick the pointed end through the hole in the middle of the blade. A balanced blade will stay parallel to your level surface. A wall-mounted blade balancer will also work. In a pinch, you can use a screwdriver in place of the cone shaped blade balancer. In any case, if the blade is out of balance, the heavy end will dip down. Bring it back to the grinder and grind the heavy end just a bit till it’s in balance. Don’t skip this step, because a blade that’s out of balance can vibrate badly and damage your lawnmower. Finally, gently rub a metal file over the edges to remove any burrs.
Now it’s time to remount the new or sharpened blade. Be sure to position the curved edges toward the housing. Secure the blade with the original washers and bolt. Use your torque wrench, and check that manual (or look online) for the correct torque. Here’s a tip: Do not make a habit of clicking that torque wrench one more just time to be sure. This will eventually ruin your torque wrench.
If your lawnmower has a bag, rinse it with a hard jet of water, both inside and out. Then hang it up to dry and leave it till spring. What you want is to get the dust and grass gunk out of the fabric. A lawn mower with a bag works by pushing air and grass through the mower and into the bag. The air goes through but the grass doesn’t. If the bag is dirty the air won’t pass through it and its function will become impaired.
If your mower is battery powered, remove the battery and completely charge it before you store it, preferably covered and in a dry environment.
That’s it, you’re done! Now you can move your mower to a clean, dry storage area, preferably in or under an outside structure, such as a shed, carport, garage or barn. Cover it – if you don’t have a lawnmower cover, use an old sheet or a tarp.
Not only will your lawnmower start right up in the spring, but you can feel good about the fact that because you’ve kept your lawnmower properly maintained, it should last you at least ten years. Maybe more.