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12 Reasons Your Ariens Lawn Mower is Cutting Uneven

You just finished mowing the lawn and look over it to admire your great work. Unfortunately, your mower left you with a disappointing bad cut. What has changed on your mower since the last time you mowed?

An Ariens lawn mower can begin cutting uneven when the mower has a low tire; worn, bent or unbalanced mower blades; bad bearings in the spindle housings or pulleys; or a worn deck belt. A plugged mower deck, an unleveled deck, a mower speed that is too fast or a ground speed that is too slow can also result in an uneven cut with your Ariens lawn mower.

Before working on your lawn mower and mower deck, follow all safety instructions listed in your Ariens owner’s manual. You will need to take precautions to keep your mower in place and prevent it from starting. This includes removing the ignition key, disconnecting the spark plug wires, and engaging the parking brake.

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Follow all safety instructions provided in your equipment operators manual prior to diagnosing, repairing or operating. Consult a professional if you don’t have the skills, knowledge or are not in the condition to perform the repair safely.

Reasons Your Ariens Mower is Cutting Uneven

Low Tire Pressure on Your Ariens Mower

Before checking anything on your Ariens mower, check your tire pressures. Your bad and uneven cut can be caused by something as simple as a low tire. Having a low tire will throw off the level of the deck making it sit lower on one side.

Use a tire pressure gauge and check your tire pressures. The pressure reading should match the recommended tire pressure shown on the tire sidewall. Add air to a low tire until the pressure is corrected.

Worn or Dull Ariens Mower Blades

Your blade tips can become so worn that a strip of grass is left between them when they turn under the mower deck. The sail on your blade can also become worn. When this happens, your blade is not able to create the air movement and suction under the deck required for a good cut.

Wearing of a mower blade is not something you can avoid. This happens under normal conditions from exposure to sand. The air flow and suction your blades create to lift the grass also draws in a lot of dirt. This dirt can wear your blade creating a dull edge and thin sail.

Check your mower blades for wearing. When the blade tips become rounded or the sail of the blade is thinner than the center of the blade, you must replace them with new Ariens blades. If your Ariens blades are in good condition, but the edges are dull. Remove your blades and sharpen them.

Bent Ariens Mower Blade

A mower blade can become bent when it contacts a solid object. Mower blades spinning at high rates impacting an object can tweak the blade and bend it. There are a couple of ways you can check a for a bent blade on and off your mower.

Before you remove a mower blade, it is a good idea to quickly check the condition of the spindle and bearing. Refer to the section on the spindle housing below.

Check for a bent blade with the blade on your Ariens mower

With your mower parked on a flat level surface. Measure the blade end from the ground to the blade. Record the measurement. Rotate the blade 180 degrees and measure from the same spot on the ground to the blade end. Record the measurement.

If you find your mower blade has more than an 1/8” difference between the two measurements, you blade is bent and should not be reused.

Check for a bent blade with the blade off your Ariens mower

For this step, have a good blade you can compare each used blade against. Place the used blade on top of your good blade and look for gaps or a bend in the blade that shouldn’t be there. Do not reuse a blade that does not sit flat against the good blade.

Never attempt to straighten a bent mower blade. Doing so will compromise the metal making it more likely to weaken and crack. There will be a risk of the blade breaking off at high speeds which can pose a danger to people, pets or structures in the area.

Unbalanced Ariens Mower Blade

An unbalanced blade is one where one side of the blade is heavier than the other. This can happen from uneven wearing or during the sharpening process when more metal is removed from one side of the blade.

An unbalanced blade can cause your blade to wobble when it rotates under the mower deck. At very high speeds, the blade can cause spindle bearing damage. A significant vibration will be sent through your Ariens lawn mower.

Use a blade balancer. It’s a handy inexpensive tool to check the balance of your Ariens mower blade before you install it. If you don’t have one of these tools, you can hang your blade on a nail in the wall. Shave metal off the heavy side of the blade until it remains level on the nail.

Ariens Mower has a Damaged Spindle or Bad Spindle Bearing

A damaged spindle or bad bearing can cause movement in your blade when it rotates under the deck. This can cause a significant vibration and an uneven cut. With your mower blade installed, grab each end of the blade. Rock it up and down to check for any movement or knocking sound.

When you feel movement or hear this sound, your bearing is most likely bad. Remove your mower blade and spindle housing to check for bearing or spindle damage. Replace any damaged parts.

Plugged Mower Deck on Your Ariens Lawn Mower

Ariens lawn mowers use the air movement of the blades along with the deck shell and baffles to create a suction to lift your grass and allow the blade to make a precise even cut. A plugged deck full of debris, dirt and grass clippings reduces the area available to create a good air flow and suction.

Not only will this cause your mower to give an uneven cut, it will also cause your Ariens’s engine to work harder to turn the blade through the debris. Keep your mower deck clean and free of debris.

Scrape the deck regularly to prevent excessive buildup. To minimize buildup under the deck, avoid mowing in wet conditions. Wet grass will clump and stick to your deck.

Ariens Lawn Mower Deck is Not Level

A deck that is not level can give you an uneven cut. When one side of your deck sits lower than the other, the mower may can give you a stair step kind of cut. Because adjustment procedures for leveling your Ariens mower deck varies by model, refer to your operator’s manual to for leveling procedures.

Makes sure your deck is level from side-to-side and front-to-rear. Note: on most deck models, the front of the deck sits slightly lower than the rear. Again, refer to your owner’s manual for exact specifications for your Ariens lawn mower deck.

Bad Ariens Deck Belt or Pulleys

A worn Ariens belt will fail to grip your pulleys and rotate your mower blades at the high speeds required for a good cut. You can tell your belt is worn when it has a shiny glazed appearance; it no longer sits tight to the pulleys; it sits deep in the pulleys; or there are cracks in the belt. Replace a worn belt with a new belt.

The bearings in your pulleys on the Ariens mower can become bad. This can cause your pulleys to not sit flat and securely to the deck. There may be some vertical movement in the pulley causing one side of the pulley to sit higher off the deck than the other side.

To check for a bad pulley bearing, slowing spin each pulley by hand. Feel for a restriction and listen for bearing noise. When you experience either of these symptoms or a wobbling, replace your pulley.

Ariens Mower’s Engine Speed is Too Low

When you engage your mower deck, you must have your Ariens lawn mower running at full throttle. You need the engine speed to be at its highest to be able to send enough power to the mower deck to spin your blades and give your lawn a good cut.

You may be running your Ariens mower and realize your engine is no longer giving you the power required to cut your lawn. If this is happening to you, have a small engine mechanic check perform tests on your engine to identify any potential problems causing your engine to not give the power you need.

Moving Your Ariens Mower at Fast Speeds

Your engine can get overloaded when mowing at fast speeds causing your Ariens lawn mower to give you a bad cut. Just like I mentioned above, an engine that doesn’t give you enough power can result in a bad mower cut.

Know your mowing conditions and adjust your speeds accordingly to not bog down your engine. When mowing tall, wet or thick grass, you must operate at slower speeds.

Additionally, slow down when operating on inclines. Mowing at too fast of speeds can cause your mower to not cut all the grass or it end sup pushing the grass over instead of cutting it.

Incorrect Overlapping of Paths with Your Ariens Lawn Mower

Overlap your mowing paths to not leave strips of grass between each pass. If you have a new mower, this can take some time to get right. You want to space your paths so you can save time and not keep mowing over the same section twice. It takes a little practice with your mower to get it just right.

Ariens Mower Deck is Damaged

If you accidentally run into a fence, tree, pole or other item, you can damage the deck shell. This can give your mower an uneven cut if it is not corrected. If you are unable to fix your deck shell, you will have to replace it with a new shell.

If you need a deck shell replacement, I recommend contacting your Ariens lawnmower dealership and getting a quote for a replacement deck shell along with the labor charge to swap all the components over to a new deck shell.

Compare this with a complete deck replacement. You may be surprised to find there isn’t a large price difference. With these two price quotes, you can make the right decision for you based on price and your Ariens mower’s condition.