Maintaining a Push Mower Part I

Push Mowers are in two basic categories.  Those categories are cheap and expensive.  For the remainder of this discourse, I am going to use the terms push mower, lawnmower, walk-behind mower and mower interchangeably.  I have noticed that the cheap mowers are selling for about $100 and the expensive mowers can readily be purchased for $500 to $600.  Either way, this is a piece of equipment that needs to be maintained.  It concerns me when people will not maintain a cheap mower and expect it to run forever.  I have met people who thought bragging rights meant that they could ignore their mower and talk about how long it lasted before it just died.

Maintenance on a push mower is simple when broken down into areas.  Sometimes the areas blend into one, but the idea is to maintain your unit as a complete unit.  I usually break the unit down in this fashion:

1. Mower Engine
2. Mower Deck (and blade)
3. Mower Drive System
4. Mower Attachments (baggers, mulchers, battery, etc)

The two most critical areas are the Mower Engine (engine) and Mower Deck.  The other areas will be discussed, but may not be installed on your mower.  The engine (no matter what the name brand) is the area that needs the most attention.  A non-functioning engine will not cut grass. 

I will start the maintenance cycle for a new mower and in the spring.  Maintenance should be performed on an hourly basis (25 hours of run time) as well as seasonal (spring, summer, fall and winter).  It is crucial that seasonal maintenance be performed.  Adding a gasoline stabilizer in the spring does nothing for the engine that has sat all winter long. 

First of all, start with the fluids for your mower.  Is the gasoline fresh?  Is the motor oil fresh?  Is the engine filled with the correct amount of fluids?  Does the engine have the correct fluids?  You don't need to run 100 octane in your engine.  However, having old, stale gasoline will not make starting any easier.  The same thing applies to motor oil.  There is a recommended viscosity for your engine.  Normally, small engines can use a straight 30 weight (30) or a combination of 10w-30 (summer use).  Read your owner's manual for the engine. 

Changing the motor oil for a mower engine is not that difficult.  Also, it's cheap protection for a mower engine.  Consider that most mower engines run at 3,000 rpm (more or less) and they are constantly working under a load (cutting grass).  Also consider that these engines do not have any oil filter on them.  Whatever gets into the oil – stays in the oil.  The motor is being lubricated by oil without being filtered.  Reading the mower manual will tell you how to change the oil.  Also, depending on manufacturer, you may have to change the oil every 25 to 50 operating hours – or – once a year (in the
fall).

The air filter is another important part of the mower engine.  Air with dust and dirt in it will cause premature wear on the internal parts of the engine.  These internal parts are the valves, cylinder, piston, piston rings and cylinder head.  If the dirt gets by the piston rings, it will get into the motor oil and cause problems within the lubrication system.  Check the air filter for general cleanliness and repair.  Change it if there is any doubt.  Again, check the owner's manual for recommended changes.

The spark plug is what ignites the gasoline in the cylinder.  A clean spark plug works better than an oil soaked, crusty one.  Ensuring that the gap is set correctly provides dependable starting.  The spark plug wire should also be checked for cracks and abrasion.  The intent is to ensure that the voltage reaches the spark plug and not be grounded out on the engine or other metal parts.

The final maintenance on the engine is the cables and associated pivot points.  Depending on your mower, you may or may not have the throttle cable.  Newer mowers are coming out of the factory with a pre-set running speed.  Basically, you prime the engine and pull the starter cord.  The speed is pre-set.  When you have finished, the operator safety device is let go and the engine stops.  However, if there is a throttle cable, it should be lubricated in accordance with the owner's manual.  Normally, the throttle cable doesn't wear out – it usually rusts and will not move.  There are pivot points on the lever that operates the throttle and pivots points around the carburetor area.  Again, read your
owner's manual for proper lubrication.

The operator safety device should also be maintained.  The device will stop the engine if you should walk away from the mower.  Depending on manufacturer, some use a spring load brake system that kills the ignition and stops the engine very quickly.  The cable and pivot points should be lubricated.  Do not lubricate the braking system on the engine!  You may also have other cables associated with the Mower Drive System.  You may lubricate them at this time, or perform the maintenance under the Mower Drive System.  

Finally, the Mower Deck and Blade are the last things to maintain under Part 1 of this series.  I can't tell you how many times I have found worn blades and clogged mower decks that cause owner's to blame the unit.  The mower deck should be washed down after every mowing.  You may get over by performing it every other time, but I have found that it is more difficult to remove dried, compacted grass under the mower deck.  The idea is that the deck needs airflow for various functions.  If you are mulching, the grass clippings need to move around to be re-cut into finer pieces.  If you are bagging, the
deck needs airflow for the blade to push the clippings into the bagger.  If you are open cutting, a clogged deck will allow clumps to form under the deck.  These clumps will build up and eventually fall off the deck.  The mower will try to cut and discharge these clumps on the lawn.  Now you have piles of grass clippings on the lawn because of clumping. 

The blade should be sharp on your mower.  Professional greens keepers (golf courses) may sharpen their blades after 3 or 4 cuttings.  A sharp blade does not rip and tear at the grass, which will cause stress on the lawn.  A dull blade will cause the engine to bog down when cutting.  This means more wear and tear on the engine.  It may also increase mowing time.  It may also increase fuel consumption.  The mulching of grass clippings may not be complete.  All of this creates an unhappy owner.  Blade sharpening is not difficult.  Again, follow your owner's manual.  I have been using a Dremel tool with a
specific attachment for blade sharpening.  There are also other grinding stones that may be used to sharpen the blade.  A sharp blade must also be balanced.  Using a pivot to ensure the blade is balanced (for weight), will ensure less vibration on the mower.  Depending on the style of your blade, you may not be able to use a grinding stone.  You may have to hand file the blade or have it professionally sharpened.  I have seen some blades with radical curves that enable the mulching process.  You may want to keep a spare blade for your convenience when sharpening.   

I haven't discussed all the safety points.  You shouldn't smoke around gasoline.  You should remove the spark plug wire while performing any maintenance.  You should never disable any safety device for your mower.  You should read your owner's manual.  You should use the proper tools for the job.  You should use the proper safety equipment on your person (safety glasses, hearing protection, foot/toe protection, etc).  Finally, use some common sense.  This is a guide and should not be construed as a final authority on the maintenance of your mower.  Read your owner's manual. 

If this guide has provided some help, please rate it.  Please see my second part in this series.  Thank you….Terry.