It’s deflating to look back at the lawn you just cut and find it looks terrible. All that work you put into having a nice-looking lawn was kind of a waste of time. Sure, the grass was cut a little shorter, but you didn’t get the quality even cut you wanted.
A push mower cuts uneven when a wheel is damaged; the cutting height adjustment is incorrectly set; the mower blade is worn, bent, or unbalanced; the mower deck is plugged; the engine speed is too low, or the ground speed is too fast.
Follow all safety precautions provided in your operator’s manual. Never work under your mower deck without first ensuring the mower will not start. This includes disconnecting the spark plug wire.
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8 Reasons Your Push Mower Cuts Uneven
A push mower wheel that is damaged or loose can cause one side of the mower to sit lower than the other. This will give you an uneven cut.
When your wheels are not the same size, a wheel is broken, or not securely attached, you must repair or replace the wheel.
Cutting Height Adjustment Set at Different Heights
Check the cutting height adjustment on your mower. Make sure all settings are at the same height. When the settings are not all the same, your push mower will not sit level with the ground leaving you with an uneven cut.
Bent Mower Blade
When you make an impact with a hard stationary object like a tree stump or rock, the blade can bend. A bent blade that doesn’t sit parallel to the ground can cause your push mower to cut unevenly.
You may be able to identify a bent blade by physically looking at it if the bend is severe. Sometimes it’s not that obvious and you’ll have to either pull the blade off to match it up to a new push mower blade or measure the blade using these steps:
- First, make sure you confirmed the wheels are of equal size and not damaged. Also, make sure your cutting height settings are all the same before proceeding with measuring your blade.
- With the mower parked on a flat even surface, measure from the ground to the blade tip. Record the measurement
- Rotate the blade 180 degrees and measure from the same spot in the ground to the blade tip. Record the measurement.
- If the blade measurements have a difference greater than 1/8”, your blade must be replaced.
Worn or Dull Mower Blade
The sail on your mower blade, which is the high side of your blade, is important to get a good cut because it creates air movement under the deck. The deck shell and the air movement created by the blades help give your lawn a nice even cut.
The push mower blade must be replaced when the metal on the sail of the blade is thinner than the center of the blade.
You must also check the blade cutting edge. The blade edge dulls from normal wear and tear. A worn blade can tear and beat up the grass instead of giving it a nice clean cut.
You may see evidence of this in a lawn where the grass tips turned brown a couple of days after you cut it.
Mower blades should be sharpened after every 25 hours of use and more frequently when you are mowing in sandy conditions. Read for more information on maintaining and sharpening your push mower blades.
Clogged Mower Deck
A push mower deck that is plugged full of dirt and grass clipping will not only make your engine work hard, it will also give you a bad cut.
The deck shell needs to be free of grass buildup so air is able to move under the deck to create a suction. This suction created by your deck shell and mower blade lifts the grass tall so the blade can pass by and give it an even cut.
Keep your mower deck clean by periodically scraping the deck with a deck scraper or metal brush. To minimize grass buildup, avoid mowing wet grass. Wet grass will stick to your mower deck and clump up in your yard.
Engine Speed is Too Slow
The mower deck requires engine power to run at its best. Make sure the throttle position on your push mower is set on high. When your mower deck doesn’t receive the power it needs, the blade tip speed slows leaving you with a bad or uneven cut.
FYI. Many lawn mowers don’t have an adjustable throttle lever. The mower automatically runs at a high engine speed as soon as you engage the bail lever and start the mower.
If you notice your engine is no longer giving you the power it once did, you should bring your mower to an experienced small engine mechanic to have the engine checked out. Read my article for other items that can make your push mower lose power.
Ground Speed is Too Fast
When it comes to mowing your lawn, you want to get the task completed as quickly as possible. However, to achieve a nice cut, you don’t want to push your mower across your yard as fast as you can.
Adjust your speed to your conditions. Mowing thick, wet, or tall grass puts extra strain on your engine. Slow down your speed when mowing in these conditions.
Mowing at too fast of speed can also cause your mower to push over grass and not accurately cut grass It can also cause the mower to bounce more across uneven ground adding to the bad cut.
Incorrect Mowing Paths with your Push Mower
Most people don’t want to spend more time than needed to mow their lawns, so mowing with the least number of paths up and down your lawn is the best to minimize that time.
You need to be careful to make sure your overlap your paths otherwise you will leave strips of grass on the lawn.
Still Having Problems with Your Push Mower?
Push mower owners encounter many common problems over a mower’s lifespan. Every mower develops issues over its lifespan even when purchasing a top-of-the-line lawn mower.
To help you identify the causes of these problems and how to fix them, I put together this guide to help: Common Push Mower Problems & Solutions.