How to Service a Cub Cadet Zero Turn Lawn Mower

Performing routine maintenance on your Cub Cadet zero-turn can extend the life of the mower and prevent small problems from developing into larger costly ones. Servicing your Cub Cadet before you begin the mowing season is putting you in the best position to minimize problems during the season.

An annual service for a Cub Cadet zero-turn lawn mower includes changing the engine oil and filter; replacing the air filter and fuel filter; cleaning around the engine and transmission; changing the transmission oil and filter if required; scraping the mower deck; sharpening the blades, and replacing worn or missing parts.

Keep reading for additional items to complete when performing maintenance on your Cub Cadet zero turn.

If you choose to have your dealership perform your annual maintenance, plan on about 2 hours of labor plus the cost of parts. If the mechanic must perform additional repairs, the expense will be greater of course.

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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.

Checklist to Service a Cub Cadet Zero Turn Mower

A Cub Cadet zero-turn mower should be serviced every 50 hours or annually, whichever comes first.

  • Check the safety systems
  • Check the starting system & battery
  • Change engine oil and filter
  • Check transmission oil level. Change transmission oil and filter if necessary.
  • Replace spark plug
  • Replace the fuel filter and inspect the fuel lines
  • Check tire pressures & lug nuts
  • Clean or replace the air filter if necessary
  • Remove dirt and debris from exhaust, engine, and transmission systems
  • Sharpen or change mower blades
  • Scrape the deck
  • Check the condition of belts and pulleys
  • Lubricate the zero-turn and mower deck

Steps to Service a Cub Cadet Zero Turn Mower

Collect Tools & Supplies to Service a Cub Cadet Zero Turn

It is best to get all of the materials together before you start servicing your zero-turn.

  • Engine Oil and Filter
  • Transmission Oil and Filter, if needed
  • Air Filter
  • Fuel Filter
  • Spark Plugs
  • Socket or Spanner Wrenches
  • Drain Pan
  • Funnel
  • Filter Wrench
  • Rags, Work Gloves, Safety Glasses, Work Surface Cover
  • Deck Scraper, Wire Brush, or Metal Putty Knife

Check the Cub Cadet Zero Turn Safety Systems

Refer to your Cub Cadet operating manual to verify the safety system is working as it should. For example, the engine should not start if the parking brake isn’t engaged. Your engine should also shut down if your PTO is engaged and the operator leaves the seat.

Go through all safety features of the Cub Cadet’s safety interlock system and ensure your mower’s safety features are reacting like they are designed to.

Also, take time to inspect the rollover protection system (ROPS) and seat belt to make sure they have not been compromised and are in good working order. The ROPS system and the seat belt are designed to work together.

Zero-turn lawn mowers are dangerous. Keeping the safety system in good working order can reduce these dangers. Read “Dangers of Zero Turn Mower & How to Operate Safely” to make sure you are following the correct safety procedures.

Check the Battery on a Cub Cadet Zero Turn

Cub Cadet zero turns use a 12-volt lawn and garden battery. Check the battery voltage using a voltmeter. If your battery reading is 12.6 volts or greater your battery is 100% charged. When the voltage reading is less than this, you need to charge your battery.

Make sure all cables are tight. Clean or replace the terminals if they are corroded. Add a dielectric grease to prevent corrosion.

Charge a Cub Cadet Zero Turn Battery

  • Disconnect the battery cables from the battery. Remember: Positive cable (Red +) is the last one off and the first one on. Now, if the battery has removable caps check the water level. If the plates inside the battery are not covered with water you will need to add distilled water to them. Note: well water is not good for a battery. City water is a little better option, but it is best to use distilled water for your battery.
  • After checking the water level, hook the charger to the battery.
  • Check the battery voltage with your meter and see what it has in it. If the battery has 11.8 volts in it you won’t have to charge it very long. If it has 10.1 volts your battery is going to need to sit on a charger for a while. The lower the voltage reading, the longer your battery will need to sit on the charger.

    I like to put a very low battery on what is called a “slow bake”. Some battery chargers have different switches on them such as 6 amps, 4 amps, or 2 amps. Charge a very low battery on 2 or 4 amps and let it charge for about an hour.

    After an hour, check the reading to make sure the voltage rate is increasing. If it is, continue to charge for another hour. If it is not increasing it’s time to purchase a new battery. You can find a battery at your local lawn mower dealership, hardware store, or automotive parts store.

Change Engine Oil and Filter on a Cub Cadet Zero Turn Mower

Your engine oil and filter should be changed every 50 hours or annually to keep your engine lubricated with clean oil. Not changing your engine oil regularly can have damaging effects on the engine. Note: If your engine is new, you need to change the oil after the initial 5 hours.

  • Prepare Work Surface: Lay covering over your work surface to prevent spilled oil from penetrating the ground. Cardboard and newspaper work well.
  • Warm Engine Oil: Start your zero-turn, park it on top of the work surface cover, and let it run for 2 to 3 minutes to warm the engine oil. Warm oil flows better than cool oil. Take caution when working around the hot engine.
  • Remove the Key & Unplug the Spark Plug Boot: Remove the ignition key and spark plug boot(s) to keep your mower from starting while servicing your zero-turn. This is a necessary safety precaution to prevent serious injury.
  • Remove Engine Oil Plug: Clean dirt and debris from the area around the oil plug or oil drain hose (depending on your model mower) so you don’t contaminate the engine when removing the oil plug. Place a drain pan under the oil plug, remove the plug and allow the oil to drain into the pan.
  • Replace Engine Oil Filter & Oil Plug: Clean around the oil filter. Using a filter wrench, remove the oil filter and replace it with a new filter. Place a light film of fresh oil on the gasket of the new filter place it on the engine. Once all of the oil has drained, reinstall the drain plug.
  • Fill with Engine Oil: Fill the crankcase with the quantity and type of engine oil recommended by your manufacturer. You must make sure you have a sufficient engine oil level. It cannot be too low or too high as either level can cause damage.
  • Start Engine and Check Oil Level: Reinstall the spark plug boots and start your engine for a few minutes. Turn the engine off and let the oil cool. Recheck the oil fluid level. Add more oil if needed.

Change Transmission Oil and Filter if Necessary in Your Cub Cadet Zero Turn

Operating your Cub Cadet zero-turn with low or old transmission fluid can cause your mower to seem weak when moving. It can also cause extensive damage to the transmission.

Most Cub Cadet zero turns must have the transmission oil changed every 200 hours. Refer to the operator’s manual for the oil change interval required for your model. If you don’t require a full transmission oil and filter change at this time, check your oil level and top off with transmission fuel if needed.

You need the oil level to reach the “full cold” line on the expansion reservoirs. These are located on the top of your mower behind the seat. You will find one for the left transmission and one for the right transmission.

NOTE: Some entry-level zero turns may have unserviceable transmission systems that don’t allow you to change the transmission oil. These are known as non-serviceable transmissions.

Refer to your Cub Cadet manual for the correct procedures for changing your transmission oil as it can vary with each model. Air must be removed from the system after an oil change.

Here are the most common directions for changing the transmission oil on a Cub Cadet zero-turn:

  • Park Zero Turn on Flat Surface: Remove the key and engage the parking brake. Wait for all moving parts to stop before working on your zero-turn. Note the engine and transmission can be hot. Take caution when working. 
  • Locate Filters & Remove Guards: You will find a filter located near each rear wheel. There may be a guard or skid plate over the filter. Remove the guard and clean around the filters before removing them. 

    Don’t skip cleaning around the filters. You do not want to introduce any dirt or other foreign materials into the transmission system. 

  • Remove Filters & Drain: Place an oil pan under one of the transmission filters. Unscrew the filter and let the oil drain. Repeat with the other transmission filter. Remove the drain pan and plan on bringing the old oil to your closest recycling center.
  • Install New Filters: Apply a thin layer of fresh transmission oil on the rubber seal of the new filters. Install the filters by turning clockwise. Once the filter makes a good connection to the filter adapter continues to turn about another full turn. 
  • Fill with Recommended Transmission Oil: Locate the expansion reservoirs. These are the little small plastic tanks on the top of your mower behind the seat. Clean around the reservoirs before you remove the caps. Fill with a good quality fresh 20W-50 oil adding oil through the expansion reservoirs until it reaches the “full cold” line on the tanks. You will have two tanks, one on each side of the mower.

    Some transaxles will have a vent plug located on each transaxle. Loosen this plug on each side. You will fill the transmission oil through the expansion reservoir until oil comes out of the vent plug. Tighten the vent plugs and continue fulling until the oil level reaches the “cold full” line on the expansion reservoir.

  • Purge Air Out of the Transmission System: It’s important to get all the air out of the system by going through some steps with the drive tires turning freely. In order to allow the drive wheels to turn freely, you will need to get the rear wheels off the ground.

    Do this by using jack stands to raise the rear of the mower just high enough so the wheels no longer touch the ground. 

    Open the bypass valve, start your mower and increase the throttle to about ½ throttle. Release the parking brake. Move the speed levers forward and reverse slowly about 6 times in total.

    Repeat this process again with the bypass valve closed until your wheels begin to rotate at a normal rate and with a normal sound.

Let the transmission system cool and re-check your oil level. Add more oil if needed.

Replace a Cub Cadet Zero Turn Spark Plug(s)

Inspect the spark plug for damage or excessive buildup on the plug. I prefer to change them out annually. It is a pretty inexpensive item to replace for the season so you don’t have to worry about an old spark plug being the cause of a starting or running problem.

If you do choose to reuse it, remove the buildup with a wire brush. Check that the spark plug is properly gapped to the engine manufacturer’s specification. Do not attach the spark plug wires until you are done servicing your Cub Cadet.

Replace the Fuel Filter & Inspect Fuel Lines on a Cub Cadet Zero Turn Mower

Gasoline can break down causing a gummy deposit that can clog the fuel filter and fuel lines. Dirty fuel is another reason why your fuel filter can become plugged restricting fuel flow. Replace the fuel filter and inspect the fuel lines for leaks.

Fuel lines need to be replaced when they become dry and brittle as they are more prone to developing leaks.

Check the Cub Cadet Zero Turn Tire Pressures & Lug Nuts

Make sure your lug nuts are tight and your drive tire pressures are equal on each side. They should be filled to Cub Cadet’s recommended tire pressure.

Uneven tire pressures can cause uneven cutting conditions. It can also cause your mower to pull one way causing your mower not to move in a straight path.

Replace a Cub Cadet Zero Turn Air Filter

Your engine requires clean air to operate efficiently. Without access to clean air, your engine is starved of air, will run sluggish, and possibly overheat. Replace your air filter annually. Remove your old air filter from the air filter housing. Be careful not to knock any dirt into the air intake.

Remove any dirt you find in the housing with a dry clean cloth. Install the new Cub Cadet air filter and reattach the cover.

It is important you regularly clean the air filter throughout the mowing season. You can find instructions for cleaning your air filter here.

Remove Dirt and Debris from Exhaust, Engine and Transmission Systems on a Cub Cadet

Remove the engine shroud and remove all dirt and debris from around the engine and exhaust areas. Clean any dirt that built up on and around the engine cooling fins. Buildup around the engine prevents air movement to keep the engine cool and prevent overheating.

Continue cleaning around the hydro fan cooling fins, guards and fan.

Check the Condition of Your Cub Cadet Zero Turn Belts, Pulleys & Spindle Housings

When servicing a Cub Cadet zero-turn, belts and pulleys must be inspected. Worn belts and pulleys can cause your transmission pump or mower blades not to work properly. If your belts appear worn or cracked having a glazed appearance to them, you need to replace them.

Over time, bearings can wear and become damaged. To check the bearings in your pulleys, you need to slowly turn each pulley to ensure they are still moving freely and you don’t feel any resistance.

While turning the pulley, listen for any noise coming from your bearing. Replace the pulley if you hear noise or feel resistance.

Check for bearing wear in your spindle housing. Do this by grabbing a hold of each side of the mower blade while wearing a good pair of work gloves to protect your hands from sharp edges. R

ock the blade with an up-and-down motion. If you feel movement, you need to replace the bearing or spindle housing assembly.

Scrape the Mower Deck on a Cub Cadet Zero Turn

Gain access to the underside of your zero-turn mower deck by using jack stands or one of these handy lifts from Amazon. Keeping the mower deck clean will provide you with a better cut and better mower performance.

Buildup underneath the deck compromises the air movement needed to create a good cut. The mower blade is designed to create air movement in the deck.

The blade along with the suction created in the mower deck makes the grass blade stand tall so the blade can pass by and precisely cut the grass blade.

Scrape the deck using a deck scraper or metal putty knife each time you service your zero-turn mower deck. A good stiff wire brush also works well.

Sharpen or Change the Mower Blades on a Cub Cadet Lawn Mower

Dull blades will put extra strain on your zero turn in addition to giving you a poor cut.  You may have noticed times when your lawn looks unhealthy with brown ends a couple of days after mowing. This is likely due to operating your zero turn with dull blades.

Not having sharp blades will beat up the grass instead of precisely cutting the grass. Each time you service the zero-turn mower you need to inspect your mower blades to determine whether they should be sharpened or replaced.

If you find a blade that is damaged or bent you must replace your mower blades.

Read more about inspecting your mower blades and the different ways to sharpen your blade with my article “Chang & Sharpen Your Cub Cadet Mower Blades”.

Lubricate the Cub Cadet Zero Turn and Mower Deck

Using a high-performance multi-purpose grease, lubricate the idler arm pivots on the deck and pumps and all other pivot points and grease zerks on your zero turn. Refer to your operator’s manual to verify all grease points on your mower. Some caster wheels will also need to be greased.

How Often Should You Service a Cub Cadet Zero Turn Lawn Mower?

A Cub Cadet zero-turn mower needs to be serviced every 50 hours or annually. In between services, the engine, transmission, and deck must be kept clean and free of debris and the Cub Cadet must be properly lubricated.

You must also check for sufficient oil levels and good tire pressures and a working safety system. The belts, filters, and mower blades must be in good condition.

Added Steps to Winterize Your Cub Cadet Lawn Mower

While many of the steps remain the same when getting your mower ready for winter storage, it is important to prepare your zero-turn fuel system. You will also need to make sure your battery is properly cared for so it does not freeze over the winter.

Read more about winterizing your zero turn in my article here.