How to Replace Exmark Mower Deck Parts

Just like with any piece of equipment, owning a lawn mower will eventually mean you will have to repair it. I love mowing my lawn with my Exmark. Mowing is an outlet for me to wind down at the end of the work day with some music playing over my headphones.  

While mowing is a stress reliever for me, I can’t say it is always a stress reliever especially when I accidentally hit an object in the yard that causes extensive damage like replacing a cutter housing or having to spend money on a new set of blades because I bent a blade. 

You have the option to bring your lawn mower to a repair center or repair it yourself. I’ll explain the steps to remove and replace Exmark deck parts.  

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Follow all safety instructions provided in your equipment operator’s manual prior to 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.

Exmark Idler Pulley 

Most idler pulley assemblies include four pieces: a carriage bolt, lock nut, pulley, and a spacer. Sometimes you will find the spacer is mounted to the Exmark deck with an aluminum teardrop-shaped piece. Other times the spacer is a bushing with a wider bottom and narrower top that goes through the pulley. 

How to Know an Exmark Idler Pulley Is Bad 

Check each pulley and turn them to make sure they move smoothly and you don’t feel resistance. If you feel resistance or hear a noise coming from your bearing, your pulley is failing and it must be replaced.

You may not have to do this procedure because your pulley seized or the bearing blew out of the center of the pulley giving you an instant indication the pulley must be replaced.

When the bearing seizes up, it may take out the bushing that holds the pulley in place. Often times Exmark owners think the bushing is part of the bearing, but it is not.   

A bearing cannot just be replaced in an Exmark riveted pulley, instead, the pulley and bearing assembly must be replaced. Exmark sells pulleys with the bearing installed.

Oftentimes, the carriage bolt will get damaged and fall out of the deck because it is only a grade 5 – 3/8 in bolt about 3 ½ inches long. 

How to Replace an Exmark Idler Pulley 

There are a couple of different ways to change your Exmark Idler pulley depending on the location of the pulley. You will need the make sure you have these four parts before you begin: 

• Pulley 
• Carriage Bolt 
• Spacer 
• Lock Nut  

Turn off Engine & Remove Spark Plug Boot 

For safety, it is necessary to turn the engine off and remove the spark plug so the engine does not start unexpectedly while you are working under the mower deck. I like to put the key in my pocket to be sure no one picks up the key and attempts to start the lawn mower. 

Remove the Deck Belt 

Most current Exmark deck models utilize a self-tensioning spring. Older models use spring-loaded tensioners that need to be removed before removing your deck belt. 

Raise the Deck to the Highest Position 

Raise the deck to the highest position so you can reach under the deck to the area with the bad pulley. You may need to use jack stands to raise the mower deck higher so you are able to get to the area needed. 

Clean the Area Where You Are Installing the Pulley 

It is a good idea to scrape the deck and remove all debris where the bolt for the pulley goes through the deck. This will ensure the bolt sits square in the deck properly. 

Install Bolt, Spacer, Pulley & Lock Nut 

From the underside of the mower deck, slide the carriage bolt through the hole in the deck. On the top side of the deck, slide the spacer over the bolt, add the pulley on top of the spacer and loosely tighten the nut with a 3/8 wrench to keep all parts in place. 

Keep the Carriage Bolt Square and Tighten the Lock Nut 

You must make sure the bolt sits square in the hole. There is a square part near the head of the carriage bolt that needs to fit squarely in the square-shaped hole of the deck.

Do this by using your hand, on the underside of the deck, to hold the bolt tight against the deck and use a socket to tighten the lock nut on the top side of the deck so it is secure. Refer to your owner’s manual for correct torque specs. 

The lock nut used is typically a flanged lock nut. The flange will make contact with the bearing in order for the pulley to spin properly. Keep in mind, this is a high-speed pulley. You will need to make sure the hardware is in place before you replace the belt. 

Replace the Mower Deck Belt 

The easiest way I have found to replace an Exmark belt is to start at the pulley nearest the engine.  

• Slide the belt around that pulley closest to the engine and pull the belts forward toward the front of the mower deck.
    
• You will find the self-tensioning belt spring on right-hand side of the deck. Wrap the belt around that tensioner pulley and then around the discharge side of the blade pulley.
    
• Continue wrapping your belt around the remaining pulleys in the pattern shown on the decal located on your deck until you get to the blade pulley on the trim side of the mower. (An image of this decal can also be found in your Exmark owner’s manual). 
• With the belt around all pulleys except the trim side blade pulley (the side opposite of the discharge chute), grab a hold of the belt with two hands and pull the belt tight. Starting on one side of the pulley, place the belt into the groove of the pulley.

  Slowly push down on the belt with the palm of your hand and guide the belt into the groove. Walk the belt around the pulley as you slowly turn the pulley so the belt falls into place. 

• Once the belt is in place, rotate the belt along the pulleys a couple of times to make sure the belt is riding along all of the pulleys. Give a tug on the belt to make sure the belt tensioner spring is reacting the way it should. 
• Because you have the deck raised, it is a good time to grease the deck, the idler arm underneath the deck, and under the unit where the hydraulic belt tensioner is located. Greasing these items will help ensure both tensioners arms have adequate grease in the cavity so they can function properly. 
• Before installing the belt covers, turn on the engine and engage the deck two or three times to make sure the belt stays in place. Install the belt covers once you confirm the belt has been installed correctly. 

Changing Your Exmark Mower Deck Belt on a Zero Turn 

Your Exmark belt needs to be replaced when you notice or experience any of the following: 

• Shiny or glazed look 
• Burnt marks on the belt 
• Frayed, cracked, or snapped belt 
• Squealing when the deck engaged 
• Mower blades slip when mowing

Remove the belt covers and lift the foot pan 

No tools are needed to remove the belt covers and foot pan on the Exmark zero-turn deck unless you have the entry-level Exmark Quest or an older Exmark 

Locate the belt decal 

Exmark places a decal on your mower deck that shows how the deck belt is routed around your pulleys. If you can’t find the decal or it has worn off your Exmark deck, pull out your phone and take a photo before you remove your belt. 

Remove your deck belt 

Most Exmark mowers have a self-tensioning spring that does not need to be removed while some of the older units and the Quest mowers use a tension spring that must be removed to change your belt. 

Install new belt 

Install Exmark Belt on Decks without a Self-Adjusting Spring 

Using the belt decal guide or photo you took, route the new belt around the pulleys and install the tension spring on Exmark models that do not have a model that uses a self-adjusting spring. 

Install Exmark Belt on Deck with a Self-Adjusting Spring 

Most Exmark mower decks use a self-adjusting spring. Follows these instructions to replace the mower deck belt.  

• Slide the belt around that pulley closest to the engine and pull the belts forward toward the front of the mower deck.
    
• You will find the spring-loaded belt tension on right-hand side. Wrap the belt around that tensioner pull and then around the discharge side of the blade pulley.
    
• Continue wrapping your belt around the remaining pulleys in the pattern shown on the decal located on your deck until you get to the blade pulley on the trim side of the mower. (An image of this decal can also be found in your Exmark owner’s manual).
   
• With the belt around all pulleys except the trim side blade pulley (the side opposite of the discharge chute), grab a hold of the belt with two hands and pull the belt tight. Starting on one side of the pulley, place the belt into the groove of the pulley.

  Slowly push down on the belt with the palm of your hand and guide the belt into the groove. Walk the belt around the pulley as you slowly turn the pulley so the belt falls into place.
   

• Once the belt is in place, rotate the belt along the pulleys a couple of times to make sure the belt is riding along all of the pulleys. Give a tug on the belt to make sure the belt tensioner spring is reacting the way it should. 
• Because you have the deck raised, it is a good time to grease the deck, the idler arm underneath the deck, and under the unit where the hydraulic belt tensioner is located. Greasing these items will help ensure both tensioner arms have adequate grease in the cavity so they can function properly.
   
• Before installing the belt covers, turn on the engine and engage the deck two or three times to make sure the belt stays in place. Install the belt covers once you confirm the belt has been installed correctly. 

Exmark Spindle and Cutter Housing 

How to Tell Your Exmark Spindle and Cutter Housing are Bad 

If you hear a bad rumble or vibration coming from your Exmark deck when you engage the PTO switch, chances are you have a bad spindle bearing in the cutter housing.

A good way to verify this is to raise the deck as high as it can go. You may have to use jack stands to get underneath the deck to get a better look. 

Before getting under the mower deck, make sure the key and spark plug boot is removed so your mower doesn’t start while working under the deck. 

Wearing a good pair of work gloves, grab a hold of each mower blade with a hand on each end of the blade. Try to rock the blade back and forth to see if there is blade movement.

Sometimes you will be able to hear the bearing knocking. If there is any movement in the blade shaft, chances are your bearing is bad and the cutter housing must be replaced. 

Replacing an Exmark Spindle and Cutter Housing 

You generally will be working with six parts when replacing a spindle and cutter housing:  

• Nut 
• Washer 
• Pulley 
• Key 
• Shaft 
• Spindle Housing 

All of these parts will not be bad and have to be replaced as long as you caught the problem soon enough. It is best to take the assembly apart to find which parts you require before running to your local Exmark dealer to buy replacement parts.  

There is a chance you may damage the threads of the shaft when you disassemble the shaft from the pulley. By taking the assembly apart before you go to the dealership, you can prevent making additional trips later when you notice you have additional damaged parts. 

When visiting your Exmark dealer, bring along your mower’s model and serial number as cutter housings and spindles vary in Exmark’s different mower decks. Having this information will help the dealership parts staff to get you the correct parts the first time. 

Taking Apart Your Exmark Spindle and Cutter Housing Assembly 

Remove Top Nut from the Center of the Pulley 

With a glove on one hand and a socket or impact gun in the other hand, remove the top nut from the center of the pulley.  

Remove Washer and Spindle Shaft 

Once the nut is removed, take the washer out of the center of the pulley and remove the spindle shaft. Most of the time, the spindle shaft will fall out of the cutter housing. If it does not fall out, you can try this: 

• Remove the keyway out of the shaft and the shaft should fall through the bearings. The keyway is a tiny bar that sits on the side of the spindle shaft.
   
• If removing the keyway doesn’t work, place the nut back on the thread of the shaft. Tap the nut with a soft mallet or a block of wood. If the shaft still won’t come out, you must purchase a new shaft along with the spindle housing. 

Remove the Spindle Housing 

Remove the spindle housing which is also known as the cutter housing. You will need to remove the six or eight bolts or nuts (depending on your Exmark model) that hold your spindling housing to the deck.

Once this is removed you can make a list of parts that are required to repair your mower deck. 

One of the great advantages of buying an Exmark mower is that the Exmark dealership has trained staff that can identify what parts you need to replace in case you are unsure.  Just bring the assembly with you to the dealership and the staff can get you what you need. 

Install an Exmark Spindle and Cutter Housing Assembly 

Remove Debris from Exmark Mower Deck 

Before you reassemble your Cutter Housing Assembly you will need to scrape the grass off from around the hole the spindle housing came from. This will ensure the new spindle housing will sit on the shell of the deck flat with no debris caught underneath. 

Secure the Exmark Spindle Housing 

Slide the spindle housing into the underside of the mower deck through the hole in the deck. Tighten each spindle housing with bolts or nuts (varies with your deck model) a little at a time using a star pattern or cross-pattern so the spindle housing is pulled tight to the deck equally. 

Refer to your Exmark’s owner’s manual for torque specs for the bolts or nuts. 

Install the Spindle Shaft 

Insert the spindle shaft through the bottom of the spindle housing towards the top of the deck. Insert the keyway into the groove so the shaft will hold in place and not fall out of the spindle housing.  

Add the Pulley 

Install the pulley on top of the spindle shaft. Install the washer with the beveled side down. Add the nut and torque it to factory specs. 

Install Exmark Blades and Replace the Deck Belt 

You can now replace your Exmark blades and install your mower deck belt using the instructions above.  You must make sure your blades are sharp and balanced before installing them. You can find more information on sharpening, balancing, and blade installation here. 

Exceptions to this Procedure 

This cutter housing installation procedure can be used on any of the three spindle housings. The only time when the procedure is a little different is when you have a double-stacked pulley on the center of the deck.

The shaft is commonly longer than the two outside shafts on those particular decks.  

Leveling Your Exmark Mower Deck 

The procedure of how to level at the mowing deck is a quite involved procedure. I recommend you bring it into the dealership for this procedure so you are guaranteed to get your quality of cut exactly the way the manufacturer intended it to be cut.  

This procedure will take 1 ½ to 2 hours for a factory-trained mechanic at the dealership. It is not something I recommend the end user perform. You most likely bought your Exmark because of their excellent quality of cut so it is important to get this correct.  

How to Change an Exmark Mower Blade 

Gather Tools to Remove Blades 

• Socket & Ratchet 
• Work Gloves 
• Safety Glasses 
• Wrench 
• Cordless Impact Gun (Optional) 

Park Your Exmark on a flat surface and raise the deck 

Move your Exmark to a flat-level surface. Make sure the blade switch (PTO switch) is off. Turn off your mower, remove the key, and wait for all moving parts to stop.  

Raise the deck to the transport position or 5-inch height position. Please jack stands under the front of the mower to support the unit while you work underneath the deck. 

Remove Spark Plug Boot 

It is an important safety precaution to remove the spark plug boot before attempting to remove your mower blades. Do not skip this step. Removing the spark plug boot will prevent the engine from starting while you work under the mower deck 

Remove Mower Blades 

Use sockets and ratchets to remove the mower blades. Sometimes a great bit of effort is needed to remove blades. A cordless impact gun works well too. 

Many people ask if lawn mower blades are reverse-threaded. Most lawn mower blades are reverse-threaded which is also known as right-hand threaded. This means you will remove the nut and bolt that holds the blades on by spinning the blade off counterclockwise. 

Removing Stubborn Blade Bolts 

If the mower blade bolt seems to be stuck, you can place a block of wood on the head of the bolt and hit the block with a hammer. This will shock the bolt and sometimes loosen it enough to help you remove it. 

Install blades 

You may have a blade set up that uses a bolt and washer to secure the blade to the Exmark spindle.  If you have a more current higher series Exmark deck you will be using a splined busing through the center of the mower blade. 

Install the splined bushing (if used on your blade assembly) into the center of the blade along with the blade bolt and washer into the spindle. Secure the blade bolt until it is finger tight 

Place a wrench on the top spindle nut and torque blade bolts to 50-60 ft-lb. 

How to Identify Exmark Mower Deck Problems 

It can be frustrating to find the cut of your Exmark mower not cutting like it did when it was new. It may be leaving an unlevel cut, a strip of uncut grass, or just making your lawn appear bad overall.

It’s good to have a checklist of what to look for when troubleshooting your mower deck problems. I can help! Read my article “Fix Your Exmark Deck Problem”. 

How to Clean Your Exmark Mower Deck 

While you have access to the underside of your Exmark deck when changing your blades, it’s a good idea to clean your mower deck to make sure it performs at its best. 

Clean Underside of Mower Deck 

Remove grass and debris from the underside of the deck and in the discharge deflector. Using a wire brush or metal scraper will help remove stubborn materials. 

Clean the Top of Mower Deck 

With the belt covers removed and the foot pan lifted or removed, clean off the top of your mower deck. The bearings are sealed in the cutter housings, but not against high pressure.

You shouldn’t use a pressure washer in this area. Instead, use a garden hose and rinse the deck around the spindle housings and pulleys.