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lawn mower maintenance

I really liked Anna Sattler's post on winterizing your lawn mower; I did most of what she recommended. I'd like to expand on her offering a bit, to show you what additional stuff I do with my mower to keep it in good shape for the summer's campaign.

After you've completed the work on your mower, look at Diane Rixon's tips on a program for keeping your turf healthy. You will likely have to make some modifications to accommodate the turf you have, but the info is good stuff.

Take a look at the gallery (also good stuff, if I do say so myself), and we'll hit the high points, with a bit of engineering thrown in for good measure.

Lawn mower maintenance -- DIY and save a buck.(click thumbnails to view gallery)

Safety first!Before and after.Also before and after.The foam pre-filter.The pre-filter, good to go.

First of all, safety: remove the plug wire from the spark plug. You laugh, but every year about 80,000 folks end up in emergency rooms with mower injuries, and I'll bet not a few come from maintenance activities. Gloves are highly recommended when handling the mower blade. And don't drop the mower on your hands when it's up in the air to remove the blade or get to the drain plug.

Materials: I needed a spark plug and a paper filter; the total cost was about US $7. I had a case of oil on hand, so no cost was incurred there, but a quart of oil runs about a buck at the auto parts store.

Time: It took me about 30 minutes to change the oil, plug, and filters. Sharpening and balancing the blade took an additional 15 minutes or so.


  • A ratchet and a 5/8" socket to remove and reinstall the blade.
  • A catch pan for the used oil.
  • A screwdriver as a balance pivot for balancing the blade, and to open the filter box on the mower.
  • A grinder to sharpen the blade: I used my drill press with a grinding wheel. Alternatively, you can use (slowly) a metal file for this exercise.

The process: here's the point where I recommend you re-visit the gallery: a picture is worth a bunch of words.

WARNING -- there's some engineering content in the following, but don't let it get in your way.

  1. Remove the plug wire from the spark plug.
  2. Remove and replace the plug, ensuring that you do not over-tighten the plug and strip the threads. To do so will cause you immense amounts of hand-wringing when you pay the tab for a machinist to re-cut the threads; it's a lot more than the price of a plug. Check the plug annually to determine the need for replacement.
  3. Remove and properly replace the air filter(s). You will likely need a new paper filter; the foam pre-filter needs only to be washed and dried before re-use. Keep in mind that the mower needs clean fuel, oil, and air to perform well. A dirty air filtration system will reduce the airflow and change the stoichiometric air-fuel mixture such that it runs poorly.

    Some mower engines allow you to change the mixture. Be careful if you do so, as it's a fairly delicate process to get the correct ratio; follow the directions carefully. Replace the paper filter every 25 hours or so; more often if you operate your mower in a dusty or dirty environment.
  4. Change the oil when it's warm -- don't burn yourself! -- so that the dirt is in suspension, and it flows more easily from the engine. Aside from the fact that dirty oil will damage the piston rings and cylinder walls, it may have a high acid content, which will ultimately corrode the engine internals. Make sure you don't overfill the engine oil crankcase and cause any damage to the engine. Change the oil every 50 or so hours, or more often if you run the machine under dirty conditions or high temps, but at least seasonally. And, for obvious reasons, don't toss the oil out in the woods or in the storm drain.
  5. Balance the blade by sharpening the cutting surfaces -- this will take a while, the first time. Be patient and take small amounts off the blades, checking the balance frequently, until you get the hang of it. I have used the screwdriver method for years; you might want to buy a balancing kit. I sharpen my blade at each oil change: a dull blade doesn't cut the grass, it shreds it, so that 's your clue to get the blade and your grinder together.
  6. Re-install the blade in the correct position; you'd be surprised how many folks put it back upside down and can't figure out why the grass doesn't get cut -- don't be one of them.
  7. Once everything is back in place, start the engine to determine how successful your blade balancing project was -- excess vibration is generally not a good thing, and that's especially true with a mower blade. An out-of-balance condition will ultimately cause a bunch of damage to the engine, and you'll be out big dollars for a new one. Other-than-normal vibration is readily apparent: to paraphrase the U.S. Supreme Court on pornography, you'll know it when you feel it. If it's not right, re-balance the blade, or buy a new one.

OK, that's my small contribution to making your things mechanical run better and helping you save money. If it's done by a small-engine-repair guy, this same tuneup will cost you over a hundred dollars. Put those savings to something else, like maybe a ball game, to see how the grounds-keeping pros make all the fancy patterns in the grass.


  • Diane Rixon

    Very thorough - thanks! And definitely the first time I've read a DIY piece that references both the Supreme Court AND porn. Hmm. ;)

    Question: I don't have a grinder wheel. How long would it take to sharpen the blade using a file and elbow grease?

  • Bill Volk

    Diane -- thanks for the comment. I suspect that it would take perhaps 20 minutes to sharpen your blade using a file; secure the blade in a bench vise, if you have one, and that will make the job a bit easier.

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