Fix Your Exmark Mower Deck Problem

Too often lawn mower owners wait for their deck to start making noise or begin to smell like burnt rubber before they consider looking at their deck. Not taking time to look at the mower deck before this happens can result in a very costly repair.

The way your lawn looks a day or two after it is mowed can indicate it’s time to look at your lawn mower deck for repair. 

These early indications can signify Exmark mower deck problems. It will be important to fix your mower deck to prevent a more costly repair:

• Tips of your grass appear brown a couple of days after you mow
• The cut of your lawn is uneven
• Uncut strip of grass is left

Read on and I’ll show you what to look at to make sure your Exmark mower deck is in good shape.

7 Steps to Find & Fix Exmark Mower Deck Problems

When addressing Exmark lawn mower deck problems, you need to start with the simple items and work your way toward the more complicated mower deck issues. These steps apply to Exmark’s zero turns, walk-behinds, and stand-on mowers.

Remove Exmark Spark Plug Boot and Ignition Key

Before proceeding with these steps, it is necessary to take precautions to ensure your safety. Working with any powered machine can be extremely dangerous. Follow these guidelines along with consulting your owner’s manual for additional safety tips.

• Make sure your Exmark’s engine is off and the key is removed from the ignition
• Disconnect the spark plug boots off the spark plug to prevent the engine from starting
• Wear heavy-duty leather work gloves to protect your hands from the mower blades

Do not start working on your Exmark until all safety precautions have been taken and all moving parts stop.

Check the Condition of Your Exmark Mower Blades

The tops of the grass will provide you with a dead giveaway your blades are dull and it is time to sharpen or replace them. What do I mean by this? Right after you get done mowing, your grass will look pretty good. The day after your lawn was mowed it may have a brown or burnt look to it.

Go out to your lawn and pull up a blade or two of grass. Look at the tips of them and you will see the blades are brown, have little cuts, or are shredded. This is actually a bruised piece of grass where the grass was beaten and not cut.

Your blades must be replaced if you notice bruised grass. If your blades are only dull and in good condition, you can remove the blades and sharpen them.

Bent mower blades can also affect the cut of your lawn. With your Exmark mower parked on a flat surface, measure from the ground to one blade tip and then spin the blade 180 degrees and measure the opposite blade tip. If there is over and 1/8″ variance, replace with a new blade.

Never attempt to straighten an Exmark blade. Repeat this step with other blades under your mower deck. I go into more detail on sharpening, replacing, and balancing blades in “Inspecting Your Lawn Mower Blades Saves You Time & Money“.

Check Your Exmark Mower Tires for Low Air Pressure

If your blades are in good shape and there is no more bruising of the grass, but you notice uneven cutes in the yard, you need to check your Exmark’s drive tires. The drive tires are the large tires on the rear of the mower.

Make sure your Exmark’s tire pressures are to the manufacturer’s recommendation. A soft tire can make your mower deck not sit level resulting in an uneven cut due to one side of the mower decking sitting higher than the other.

Exmark Mower Deck Height Must Be Level

If your lawn mower tires are set to manufacturer specification, the next step to perform is to check the deck height. Make sure your Exmark mower is parked on a flat surface.

Measure the deck height on all four corners of the mower deck to ensure the measurements are all the same. If they are not, make adjustments according to your owner’s manual.

Leveling the deck can be a little tricky and sometimes can take a trained dealer up to two hours to adjust. If you have a hard time making the adjustment, you can have your local Exmark dealer take care of it.

Check the Exmark Deck Bearing in Spindle Housing

If your deck is level and you still have a bad cut, you need to check your Exmark mower deck bearing(s) under your deck. Again, check to make sure the spark plug boots are off the spark plugs for safety. Some small engines will have one spark plug while others have two.

Making sure the spark plug boots are removed will prevent the engine from starting. Be very careful and put on a good pair of leather work gloves to protect your hands.

Grab a hold of one Exmark blade at a time at each end of the blade and see if you can rock the blade up and down. Feel this motion and listen for a nock. If the blade moves or creates a noise, you have a bad bearing in the spindle housing, or a quill assembly, as they are sometimes called.

You have to make a decision whether you are able to rebuild it or if it is just easier for you to replace the cutter housing assembly which typically includes the bearing.

Your Exmark dealer will typically only carry the complete cutter housing assembly and will not recommend rebuilding for longevity reasons.

For instructions on how to remove and install your spindle housing, read, “How to Replace Exmark Mower Deck Parts“.

Check the Exmark Mower Deck Belts

Now we know your Exmark’s blades, tires, deck level, and deck bearings are all okay, but your yard still looks bad. It is time to look at the Exmark deck belts and the pulleys the belts run on. So if your belts have a shiny or glazed look to them on the edges, you need to replace them.

Check Exmark Deck Pulleys & Idler Pulley Brackets

Look at the Exmark pulleys and idler pulley brackets. To check your pulleys, with the mower deck belt off, spin them to feel they move smoothly and listen for noise.

If there is any noise or any restriction when moving the pulley, the pulley needs to be replaced. Check the idler pulley bracket to make sure there isn’t any play where it mounts to the deck. Any movement will require a new pulley bracket.

If your Exmark idler pulley bracket has not been greased in a while it may not move as it was designed to do. The reason why the bracket needs to have movement is so you can turn the blades on and the instant load won’t snap the Exmark deck belt.

To prevent the belt from breaking, the idler pulley bracket is designed to move and spring back to put tension back on the belt. If the bracket is unable to move, the belt can slip and cause the blades to also slip in heavy or deep grass so our cut looks bad the next day.

Some of the idler brackets will have a bushing installed in them while others may use bearings. The bushings will be either plastic or brass. The parts depend on the type of mower you purchased. Most Exmark mowers will use brass bushings or bearings.

This idler pulley bracket usually is a part that has a grease zerk on it. If yours does not, you will have to take it apart, grease it up and put it back together so it has movement once again. Keep the idler bracket greased when doing your routine maintenance checks throughout the mowing season.

Grass Stuck Under Exmark Deck Can Affect Quality of Cut

You need to keep in mind that grass stuck under your deck can disrupt the quality of cut also. You may not think scraping your Exmark deck is that important, but it really is.

You have to remember the depth of the deck gives us an area to stand grass up so the blades can pass by and create a nice cut.

If the grass plugs up this space you lose under the deck will cause you to lose the lift of the grass created by the movement of the blades.

Many people ask if there is a way to keep grass from sticking to the bottom of the Exmark deck. You’ll never be able to prevent grass buildup under your lawn Exmark deck altogether, but here are a few ways to reduce the amount of grass sticking to your mower deck:

• Always run your Exmark mower at full throttle
• Avoid cutting wet grass
• Regularly cut your lawn so the grass doesn’t get too long and result in clumping of grass
• Coat the underside of your Exmark deck with a Teflon or silicone spray designed for your lawn mower deck

How Often Should You Perform Exmark Mower Deck Maintenance?

The lawn mower deck is the main component of your Exmark mower, but I think it is often the most neglected. 

For the average homeowner, Exmark mower deck maintenance should be performed at least twice per mowing season. If your yard is heavily watered or fertilized you need to perform maintenance more often.

The grass is full of moisture and fertilizers, if you use it, that can create erosion of the deck so you may not get the life you expected out of your Exmark mower deck. Scrape and clean out the undersides of your decks more than once a year.

While you are under the deck, use the steps above to identify all mower deck parts are functioning as needed and are in good condition. Performing these routine checks will help you prevent more costly repairs.

What is Causing My Exmark Deck to Vibrate?

Exmark mower deck vibration can be caused by bad bearings in the cutter housing, unbalanced blades, or debris wrapped around the blade shaft or lodged in the components of the mower deck.

Exmark Mower Maintenance

Not only is it necessary to take the steps to maintain your Exmark deck, but it is also important to protect the maintain the engine, transmission, and other components to make sure the mower continues to operate in top condition.

For more information on the upkeep of your Exmark lawn mower read my articles, “How to Exmark Zero Turn Hydraulic Oil & Filter” and “How to Winterize Your Exmark Lawn Mower“