Exmark is known for its superior cut quality. Exmark mower decks utilize a patented baffle system that controls air flow contributing to its great cut.
It’s a quality of cut many lawn mower manufacturers have sought to achieve. In fact, Exmark has won a patent infringement lawsuit against a major manufacturer who implemented the system into their mower decks.
An Exmark can give you a bad or uneven cut when the mower has a low tire; worn or damaged deck components; or a clogged mower deck. Operating your mower incorrectly with the engine speed too low, the ground speed too fast, or with inaccurate mowing paths can also result in an uneven cut.
You probably paid a premium to buy an Exmark mower over another brand for its cut quality. Let me help you troubleshoot your cutting problem so you can continue to get that premium look you require from your Exmark.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
12 Reasons Your Exmark Mower Cuts Uneven
|Cause for Uneven Exmark Cut
|Solution for Uneven Exmark Cut
|Worn mower blade
|Sharpen blade. Replace with the new blade when needed.
|Low tire pressure
|Check tire pressures and bring them to the correct level
|Bent mower blade
|Replace mower blade
|Blade is incorrectly installed
|Remove and install with the blade sail point upward
|Clogged mower deck
|Scrape the deck
|Deck is not level
|Level the deck from side-to-side & front-to-back
|Damage to spindle or spindle housing
|Replace damaged spindle or housing
|Bad deck belt or pulleys
|Replace worn belts and pulleys
|Engine speed is too low
|Run your mower at full throttle
|Ground speed is too fast
|Mow at the correct speeds for your mowing conditions
|Incorrect mowing paths
|Overlap paths so strips of uncut grass are not left
|Deck shell is damaged
|Repair or replace your mower deck shell
Worn or Dull Mower Blade
Strips of grass can be left behind when your Exmark blades become very worn. Dirt and debris cause your metal blade to wear becoming dull and thin. This is considered normal wear on your mower blades.
A yard that has a thick blanket of grass with less exposed dirt will wear blades slower than a yard that is not as thick and more dirt is being sucked into your Exmark mower deck.
Inspect your blades for wearing when you notice strips of uncut grass or when brown tips form on your grass a couple of days after you mow.
The brown tips occur when your grass isn’t getting a nice fresh cut from sharp mower blades. Dull blades tend to beat up your grass causing it to turn brown.
Sharpen your Exmark mower blades when they become dull. Replace your blades when they are worn where the sail of the blade is thinner than the center of the blade. I share more about sharpening and replacing Exmark mower blades here.
Tire Pressures are Not Correct
Before you move on to the next steps, you need to first check the tire pressures. Tire pressures can throw off your deck heights causing one side to sit higher off the ground.
Skipping this step may cause you to make unnecessary deck adjustments that will have to be reversed once you identify your Exmark tire pressures are not correct.
A low tire can cause your Exmark to have an uneven cut. Use a tire pressure gauge to check pressures in each drive tire. The tire pressures should be the same in each tire and should be filled to the tire manufacturer’s recommended pressure found on the sidewall.
Add air as needed to correct the tire pressure levels on your Exmark. Once you have confirmed you have good air pressure levels, you can move on to looking at your mower deck for your uneven cut problem.
Bent Mower Blade
A mower blade can bend when it makes contact with a solid object. This could be a rock, stick, toy, or other object left in the yard.
To minimize the objects your Exmark blades come in contact with, walk your yard prior to mowing and remove any objects or debris that can cause damage to your mower deck.
The impact an object can have on your mower blades can be so significant you feel a jolt when mowing. You know to look at your mower blades for damage because of the severe impact.
Other times, the impact can be minimal. You may not know to look at your mower blades until you start seeing a bad or uneven cut.
A bent blade can cause your Exmark to give you an uneven cut even if it is only a slight bend. There are a couple of different ways to check for a bent mower blade.
- Check for Bent Exmark Blade Method 1: Remove your Exmark blade from your mower deck and place the blade on top of a new blade. If your old blade lays on top of the new blade without any bends or gaps, your blade is not bent and you can continue to use it as long as it is not extremely worn.
If you do not want to remove your mower blade to check for a bend or don’t have a new blade to match it up to, you can proceed with method two for identifying a bent Exmark blade.
- Check for Bent Exmark Blade Method 2: Park your Exmark mower on a flat-level surface. Measure one side of the blade from the ground to the blade tip. Record the measurement. Next, rotate the blade 180 degrees and measure the other side of the blade from the ground to the blade tip.
If the measurements are greater than a 1/8” difference, you need to replace your mower blade. Repeat this process to check additional blades on your mower deck.
When you find a bent blade, remove it and replace it with a new blade. However, before you remove your blade, I recommend checking for damage to your spindle housing caused by an impact on the blade. Put on a good pair of work gloves so you don’t cut your hands on the blade edges.
To check the spindle housing, grab a hold of each end of the blade. Rock the blade up and down checking for excessive play or a knocking noise indicating you have a problem in your housing.
If you feel movement or hear a knocking noise, remove the spindle housing and check for damage to the bearing or spindle. I have more information on changing out an Exmark spindle housing here.
Never attempt to straighten a bent Exmark blade to reuse it for safety reasons. Straightening the blade will compromise the metal and make it weak. The weak metal on a spinning blade at high speeds is a recipe for disaster.
The weakened metal can break off and fly out of your mower deck at a high speed putting people, pets, and other items in the area at risk of injury or damage.
Blades are Not Installed Correctly
Blades Facing the Wrong Way
When your Exmark mower blades are installed incorrectly, with the blade sails facing the ground, damage can occur to your lawn and your spindle housings.
When blades are installed upside down, the blade will beat up and tear your grass causing an uneven cut. The blade sails can also impact the ground causing spindle housing damage.
Your Exmark blade must be installed with the sail, or high sides, of the blade facing upward. Exmark OEM blades have the part number located on the bottom of the blade.
Some aftermarket mower blades will have a stamp with the word “BOTTOM” or “THIS SIDE DOWN” o the blade to indicate which side of the blade faces toward the ground. If you always remember “Sail Up!” you’ll install your blades the right way each time.
Wrong Blade Hardware is Installed
Next, make sure you are using the correct hardware to install your blades. Some Exmark blades use a washer and bolt, while others require a washer, bolt, and splined bushing for installation. Use the required hardware for your Exmark when installing your mower blades.
Do not use an impact gun to install your blades as over-tightening your bolt can cause spindle damage. Use a wrench for blade installation and torque to 50-60 ft-lb.
Blade is Not Balanced
Your Exmark blade must be balanced before installing them on your mower. A new set of mower blades will not have to be balanced, but a set that has been sharpened must be balanced to prevent vibration and additional damage to your Exmark.
A balanced Exmark blade has equal weight on each side of the blade. The best way to check the balance of your blade is by using a blade balancer. This isn’t that expensive of a tool.
It is definitely worth the investment because an unbalanced blade cannot only cause damage to the spindle assembly but can also cause additional strain on your engine.
Another method to check for a balanced Exmark blade is by hanging the blade on a nail that is mounted to your wall with the nail head sticking out of the wall about 3/4″ to 1″. You will need to remove metal from the end of the blade that is hanging lower until the blade sits level.
Deck is Plugged with Grass
Grass and dirt collecting under your mower deck can cause your Exmark to give you a bad or uneven cut.
Exmark uses the area under the deck in combination with the air created by the mower blades, to create a suction in the deck to stand your grass tall. When the grass is lifted, the blades will cut your grass at an even height.
A plugged mower deck takes away the amount of area available for air movement. Your quality of cut will suffer making your Exmark cut uneven. A clogged mower deck can also cause additional strain on your engine when the blades need to work through a large collection of debris with each turn.
It’s important to keep grass from collecting under your deck. You can do this by regularly scraping your deck with a deck scraper and following these tips:
- Don’t cut your grass while it is wet. Wet grass clumps and collects under your mower deck. It also leaves clumping in your yard.
- Use a silicone or Teflon spray to coat the underside of your mower deck. While this does help reduce the amount of grass collecting under your deck, it will not prevent all grass from sticking. The nice thing about using a coating under your deck is the need to scrape your deck is less frequent. Make sure you are spraying a clean deck and allowing the coating to dry before using your mower.
Mower Deck is Not Level
A mower deck that doesn’t sit level can cause your Exmark mower to give you an uneven cut. Have your owner’s manual available to verify the exact specifications for your mower model.
Exmark has many different models and series of mower decks that have varying steps to measure and adjust the deck.
Using the procedures and measurements listed in your owner’s manual, make sure the deck sits level from side-to-side and you have the correct rake from front-to-rear.
I find it best to bring my mower to my Exmark dealership so they can level the deck to the correct position so I can continue to experience the great cut Exmark is known for. If I didn’t care about Exmark’s cut quality, I would have purchased a less expensive mower.
Spindle is Bent or Bearing is Worn in the Spindle Housing
Check for a bent spindle or a failed bearing in your spindle housing that may be causing your bad cut. With a pair of heavy gloves on, grab a hold of each side of the blade and rock it up and down. Listen for a knocking noise and feel for any movement in the blade.
You will need to remove your Exmark spindle housing and inspect it for damage if you hear knocking or feel movement. Your spindle bearing is most likely bad.
A bad spindle or bearing can cause your blade to sit unlevel leaving space between the blade tips. This space will give you an uneven cut with your Exmark.
Belt or Pulleys on Your Exmark
Your Exmark blades can fail to move at high speeds when your Exmark deck belt is worn or loose and fails to move around your pulleys. Bad pulleys can also cause this problem.
Inspect your deck belt checking for signs of wearing including a shiny glazed appearance, and a frayed or cracked belt. Replace a worn Exmark belt. I only use original equipment manufacturer (OEM) belts on my Exmark to ensure I have a high-quality belt that will not hinder my deck’s performance.
To check your pulleys, hand spin each pulley to make sure they are moving smoothly. If you feel any type of restriction or bearing noise coming from the pulley, you need to replace the pulley. If you find a pulley isn’t sitting flat and parallel to the deck, you must replace it.
Engine Speed is Too Low
To get a good cutting performance from your Exmark, you must be running your engine at full throttle when the mower deck is engaged.
If you are running your mower at full throttle and your engine doesn’t feel like it’s giving you the power it once did, have your Exmark checked over at your local Exmark dealership or small engine repair shop.
Ground Speed is Too Fast
Your ground speed needs to be adjusted to your mowing conditions to receive a good cut. If you don’t properly adjust your speeds and move too fast through your lawn, your Exmark mower will give you a bad or uneven cut.
Your lawn mower is put under heavier loads when it is cutting thick, tall, or wet grass than cutting in other conditions. You must slow down so your mower is better able to handle the load.
Incorrect Overlapping Path
Making fewer passes with your Exmark mower will allow you to complete your mowing quickly, but you may find strips of uncut grass if you don’t properly overlap your cuts. Work on adjusting your paths to get the best coverage while not leaving any grass uncut.
Mower Deck Shell is Damaged
A damaged mower deck can cause your mower to give you a bad or uneven cut. You could have accidentally hit an obstruction when you got moving a little too fast. You may be able to repair your deck shell or you might have to replace it.
If you are having your Exmark dealership replace your deck shell, you may want them to quote a complete deck assembly as well.
Depending on the age of your mower deck and the amount of labor required to swap all your components over to the new deck shell, it might be worth it to just buy a new mower deck.
Your Lawn is Uneven
If you are like me and have a lawn that is not perfectly level, you may run into areas where your mower deck is scalping your yard. This can happen when you have a high spot in your yard. Another area where I see a lot of scalping is in shallow ditches.
A wide format mower deck can’t adjust with a bend or dip in the yard and therefore scalps the yard or creates an uneven cut. When mowing ditches, it is best to use a smaller format deck like those on a push mower.
Still Having Problems with Your Exmark Lawn Mower?
I’ve put together a handy guide for the most common problems an Exmark owner will encounter. When you own a mower long enough, you are going to run into many different issues with your lawn mower.
Check out and bookmark this page to use as a reference when you need help with your mower: Common Exmark Lawn Mower Problems & Solutions