How to Maintain a Small Gas Engine Lawn Mower

The most improtant maintenance you'll ever perform on your small gas engine lawn mower is after the final cut every fall.

Here's how to get the most bang for your buck and make that lawn mower last for years to come.

Difficulty: Moderately Easy

Instructions

1. Change the oil.
   
   This is number one on the list for a reason! It is the most important step. Dirty oil will shorten the life of a small gas engine.
   
   Changing the oil in the fall makes more sense than doing so in the spring. Why allow impurities in the old oil to stay in your engine all off season? They have a negative effect on your engine even while it is not running.

2. Drain the fuel tank.
   
   You can put this and any gas remaining in your lawn mower gas can into your car's fuel tank. Then use up the gas still remaining in the carburetor and fuel line by running the mower until it dies. Emptying the engine of old gasoline prevents evaporation and oxidation, which possibly results in formation of insoluble gum that clogs up the carburetor.

3. Check the air filter.
   
   If it is dirty, blow it out thoroughly with compressed air or replace it altogether.
   
   Also check the fuel filter if there is one on your particular lawn mower. Replace if there is any doubt whether it is clogged.

4. Remove and inspect the spark plug.
   
   If the curved electrode and/or tip is black, replace the spark plug. They should be light gray or brown. Again, if there is any doubt then replace this part! A spark plug for a small gas engine lawn mower is most likely not going to cost even $3, so just do it. Make sure you get an exact replacement! Not just any spark plug that will fit the threads and screw in will necessarily work.

5. While you have the spark plug out, coat the cylinder using a protectant such as WD-40.
   
   You can also use just a dab of new engine oil for this step. Crank the engine a couple of times to distribute the protectant evenly. This will prevent the engine's cast iron cylinder liner and piston rings from developing rust while the lawn mower is stored.

6. Inspect the cutting blade.
   
   Have it sharpened if need be. Replace it if there are any substantial dents (dings are okay), bends, rips or tears in the blade.

7. Clean, clean, clean.
   
   Air flow is important for a small gas engine for running properly and cooling. The less dirt, leaves, and other debris, the better! Do not wash your lawn mower with water, however. Remove the big stuff by hand and then blow and/or wipe the mower clean.

8. Lube!
   
   Lubricate any throttle, choke, chains, pulleys, cables, etc. with a few drops of oil or spary lubricant. The idea is to keep moving parts moving and not let them freeze up like the Tin Man!

9. Keep 'er dry.
   
   Store your lawn mower under a shed roof or in the garage. If this is just not possible then at least cover the engine with a tarp, a plastic bag or tub or something to protect it from the elements. After a rain remove the covering for a time to allow moisture to escape.

Resources

• Maintain and repair 4-stroke small gasoline engines for compressors, generators, pumps, motorcycles, snowmobiles, lawn mowers and more!
• Watering Your Lawn and Garden

[paulo55]

on 10/10/2009 Great article! Well written and good information! 5*

[cash21]

on 8/22/2009 Very good article This comes from someone who spends 4-6 hours mowing every other weekend! (on a riding mower of course)!! 5*

[sonni57]

on 5/29/2009 Yikes I need to clean my lawnmower that must be the problem!

[athome]

on 5/27/2009 Now All I Need Is A Small Gas Engine Lawn Mower 5*

[xtraordinary]

on 5/25/2009 Great article, Texasparky. Very thorough and well-written. To me it translates into "find a man to do this stuff," but I can tell that you really know what you're talking about! 5 stars~