12 John Deere Mower Problems (John Deere Troubleshooting)

No matter what brand of mower you own, when you own it long enough, you will run into problems that will need to be repaired to ensure it keeps operating at its best. The same is true of John Deere lawn mowers.

John Deere has a strong reputation in the equipment industry, but just like other manufacturers, their equipment doesn’t last forever without issues developing along the way.

I have put together a list of common issues for John Deere riding mowers, lawn tractors, and zero-turn mowers and how to solve these issues. You will find links that provide more in-depth information on each problem including troubleshooting steps.

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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.

John Deere Mower Problems: Riding Mowers, Lawn Tractors & Zero Turns

1. Won’t Start

When your lawn tractor or zero turn won’t start, look at items that can cause an air or fuel restriction. Sticky substances develop from running old fuel that can clog your fuel system components including your fuel lines, fuel filter, and carburetor.

Making sure you run the correct gas through your John Deere and properly care for your fuel will help prevent starting issues due to fuel.

Other items to check on your John Deere include the battery, safety switches, and charging systems. A charging system that fails to keep your battery charged will prevent your mower from starting. Electrical components that don’t work right can also contribute to the problem.

Detailed information can be found at:
Reasons Your John Deere Mower Won’t Start

Cause	Reason for Problem	Solution
No gas in the fuel tank	Fuel tank is empty	Fill with fresh fuel
Bad or old fuel	Fuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system	Drain the fuel tank and fill it with fresh fuel. Use a fuel additive like Sea Foam to stabilize the fuel and assist with cleaning the fuel system. Use the right fuel.
Faulty or clogged fuel cap	The vent in the cap can get clogged causing your tank to form a vacuum restricting fuel flow	Use a thin piece of wire to try to clear the clogged vent. Replace the cap if needed.
Bad spark plug	Excessively dirty or broken spark plug; bad connection; not gapped correctly	Replace with a new spark plug, secure connections, and ensure it is gapped to manufacturer specifications
Plugged air filter	Dirt and grass can plug the air filter preventing airflow	Remove the filter and clean it. Replace the filter if it is in bad condition.
Plugged fuel filter	A dirty fuel filter will restrict fuel flow	Replace the fuel filter
Bad fuel pump	A failed or leaking fuel pump will no longer create the pressure needed to pump fuel	Replace the fuel pump
Blocked fuel lines	Bad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuel	Use a carb cleaner and compressed air to clear the clog out of the fuel line. Replace the line if necessary.
Dirty carburetor	The carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flow	Clean the components making up the carburetor. Replace if needed.
Bad battery or loose & dirty terminals	A dead battery, loose cables, or corroded terminals can cause starting problems	Charge your battery and replace it if it won’t hold a charge. Make sure your cables are tight and clean the corrosion from terminals.
Bad safety switch	Safety switches are a safety measure that exists to prevent your mower from starting in certain situations. When a switch fails, your mower may not start.	Test and replace faulty safety switch
Bad ignition switch or coil	Your mower will not start when either the ignition switch or coil is bad	Test and replace a bad switch
Broken recoil	A pull start mower may have a damaged or broken recoil preventing the recoil to initiate starting your engine	Check the recoil to see if it can be restrung or if broken parts, like the pulley, can be replaced. Replace the recoil assembly if needed.

2. Starts and Dies

Many of the same reasons that cause your mower not to start can cause your John Deere to lose power and die.

When your mower isn’t able to get the right amount of fuel and air it needs to run efficiently, it can begin to run sluggishly and possibly shut down. Check all items of your fuel and air systems for restrictions.

Overheating can cause your John Deere to die. It’s important to use the correct engine oil; maintain the correct engine oil levels, and clean out your engine cooling fins and around the engine so air can circulate around your engine to keep it cool. Find out more about overheating here.

Your electrical system or clogged mower deck can also cause your mower to die after it has been running.

Detailed information can be found at:
Why Your John Deere Mower Starts Then Dies

Cause	Reason for Problem	Solution
Bad fuel	Fuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system and engine damage	Drain the fuel tank and fill it with fresh fuel. Use a fuel additive like Sea Foam to stabilize the fuel and assist with cleaning the fuel system
Plugged air filter	Dirt and grass can plug the air filter preventing airflow	Remove the filter and clean it. Replace the filter if it is in bad condition.
Dirty or broken cooling fins	Cooling fins get packed with dirt, oil, and grass not allowing air to effectively cool the engine block	Replace broken fins and clean the cooling fins.
Clogged fuel lines or filter	Bad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuel	Use a carb cleaner and compressed air to clear the clog out of the fuel line. Replace a plugged fuel filter.
Dirty carburetor	The carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flow	Clean all components making up the carburetor. Replace if needed.
Too Much Engine Oil	Too much engine oil increases pressure in the crankcase causing it to overheat and die	Correct your engine oil level by removing a little oil
Bad Spark Plug	Dirty or damaged spark plug causes the plug to foul out and cause intermittent running problems.	Clean or replace spark plugs if needed. Ensure spark plug wires are securely attached and the plug is gapped correctly.
Faulty Ignition Coil	A windings on the coil can separate and short out a bad ignition coil	Check for a break in the continuity using an ohm meter and replace is found bad
Choke is in the Wrong Position	A choke is used for cold starts. The choke can cause your engine to shut off when it continues to restrict airflow after the engine warms.	Make sure the choke is in the correct position
Bad Gas Cap	Gas caps have vents for air to pass through. When the vents get plugged, the fuel tank will cause fuel restrictions.	Replace a fuel cap that no longer vents
Clogged Mower Deck	A clogged mower deck causes a strain on the engine causing it to work hard and possibly shut down	Periodically scrape your mower deck to keep it clean

3. Mower Smokes 

Something as simple as a plugged air filter can cause your John Deere to smoke. Smoke is often created when your mower is running rich emitting black smoke because it is running a higher ratio of fuel to air.

It can also be created when oil is burning off due to oil in the cylinder or possibly from an oil leak onto a hot muffler.

Detailed information can be found at:
Why Your John Deere Lawn Mower is Smoking

Cause	Reason for Problem	Solution
Plugged air filter	Dirt and grass can plug the air filter preventing airflow	Remove the filter and clean it. Replace the filter if it is in bad condition.
Too much oil in the crankcase	Excessive oil can cause pressure to build in the engine allowing oil to get into the cylinder through the valve train	Drain a little engine oil until it is at the manufacturer’s recommended oil level.
Engine oil level is too low	Lack of oil can increase friction in your engine causing extreme heat.	Bring to a small engine repair shop to inspect engine damage. You can try adding oil, but it is often too late to this fix your engine problem.
Internal problems including the piston ring, valve train or engine gasket	Internal engine problems can have a detrimental effect on your mower if they are not caught soon enough and fixed.	Bring your John Deere to your local small engine repair shop for troubleshooting

4. Weak Hydrostatic Transmission 

Cause	Reason for Problem	Solution
Bad drive belt	A bad drive belt can cause your pump not to work efficiently	Replace a frayed, cracked, or worn belt
Bad tensioner pulley	When a tensioner pulley fails, it fails to keep tension on the drive belt	Replace the pulley and grease the tensioner arm
Low or old hydraulic oil	Low or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weak	Change your hydraulic oil at regular intervals as recommended by John Deere. Check your hydraulic oil periodically to ensure your hydraulic fluid is full. (Some transmission systems are sealed and they can’t be serviced. If you are having trouble with a sealed system, see your dealer).

5. Won’t Drive Straight or Steer Correctly

It can get frustrating when you are always having to adjust the operation of your mower because it is pulling to the right or left. Here is a list of items to check on a zero-turn or riding lawn mower to make the necessary corrections to get your mower to drive straight.

Cause	Reason for Problem	Solution
Incorrect tire pressure	Unequal tire pressure can cause your mower to pull to one side.	Check tire pressures and keep them filled to the manufacturer’s spec. Tires on each side of your mower require equal pressure.
Bad dampers on zero turn	Bad dampers will cause your mower to jerk to one side when moving forward	Replace with a new damper
Tracking adjustment needed on zero turn	When one tire is moving faster than the other, your mower can pull to one side	Adjust the speed adjustment bolt to change the rotation speed of the tire. Refer to your owner’s manual.
Worn or loose steering components in riding mower	Worn bushings, washers, and gears can cause your mower to not steer one way or the other	Inspect and replace the parts that failed on your steering system

6. Mower Won’t Move

Detailed information can be found at:
9 Reasons a John Deere Zero Turn Won’t Move or Go Forward

Cause	Reason for Problem	Solution
Drive release lever in the wrong position	The drive release lever allows hydrostatic mowers to roll freely	The drive release lever must be in the operating position.
Missing key in the axle	Your riding mower may have a small key in the axle that may have fallen out of place	Replace the key in the axle
Drive pump belt is worn	The mower won’t move if your drive belt has fallen off. It could also not move if the belt is worn.	Replace a worn or cracked belt. Make sure the belt is securely around the pulleys.
Bad tensioner pulley	The bearing in the tensioner pulley can fail	Replace the tensioner pulley
Missing idler arm spring	If the idler arm spring breaks or goes missing, it can no longer place tension on the drive belt	Replace the broken or missing spring
Low or old hydraulic oil	Low or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weak	Change your hydraulic oil at regular intervals as recommended by John Deere. Check your hydraulic oil periodically to ensure your hydraulic fluid is full. (Some transmission systems are sealed and they can’t be serviced. If you are having trouble with a sealed system, see your dealer).
Hot hydraulic fluid	Hot hydraulic fluid can be a sign of damage to your hydrostatic transmission system	Let your hydraulic oil cool. If you find your mower runs fine when it is cold, but becomes weak when the hydraulic system gets hot, have your mower checked at your local John Deere dealership.
Air in the hydraulic system	Air must be bled from the hydraulic system after changing your hydraulic fluid or the mower will not be able to move at normal speeds	Follow John Deere’s procedures for changing the hydraulic fluid and bleeding air from the system in your owner’s manual.

7. Mower is Vibrating

Something as small as a pebble or acorn can cause your mower to excessively vibrate. Debris stuck in the mower, loose hardware, missing engine mounting bolts, and a bad clutch can all contribute to your John Deere shaking.

You must check your mower deck when looking for a vibration. Damaged or unbalanced mower blades, components on your deck, and bad bearings can cause your mower to vibrate.

Detailed information can be found at:
How to Stop Your Lawn Mower from Shaking & Vibration

Cause	Reason for Problem	Solution
Loose or missing engine mounting bolts	Engine bolts are used to reduce the vibration of the mower when the engine is running	Secure engine bolts and replace any missing bolts
Clutch is bad	When there is bearing failure and it falls out of the clutch it can cause vibration. A manual engagement clutch can have a bushing and linkages that can fail.	Replace the clutch
Unbalanced or damaged mower blades	Damaged and unbalanced blades can send a vibration through your mower. Blades must be balanced before installing	Replace any damaged blades and make sure they are balanced.
Material wrapped around the blade spindle	Foreign materials like string or long weeds can get wrapped around your blade shaft causing vibration	Remove all debris and items wrapped around the blade shaft. Check for spindle damage.
Bad spindle housing bearings	Vibration can be caused by a bad bearing in the spindle housing.	Replace the bearing in the spindle housing or replace the whole spindle housing assembly
Worn pulleys or deck belt	Check deck belt and pulleys for wearing of the belt and bearing failure in the pulleys	Replace any damaged or worn belts and pulleys
Debris lodged in mower	The smallest little things can cause your John Deere to excessively vibrate. Check over your mower for debris stuck in the deck or mower. Don’t overlook the small stuff.	Check over your mower deck and mower for any place small items can be stuck in your mower. Remove these foreign materials.

8. Mower Deck Has a Bad or Uneven Cut

Your John Deere mower usually gives you a nice cut each time you mow, however, you have noticed your lawn looks bad with an uneven cut. It’s important to start by confirming the tire pressures are correct before you move on to checking and adjusting your mower deck.

Detailed information can be found at:
Reasons Your John Deere Mower Cuts Uneven

Worn mower blade	Uneven tire pressures	Engine speed is too low
Bent mower blade	Unleveled mower deck	Ground speed is too fast
Blade installed wrong	Bent blade spindle or spindle bearing	Damaged deck shell
Clogged Mower Deck	Worn deck pulleys or belt	Operator error

9. Mower is Leaking Gas

When gas evaporates into the air, it can often be hard to find the place your John Deere mower is leaking gas. There often isn’t a large wet spot to clue you into your problem area. Here is a list of things to check on your mower.

Detailed information can be found at:
Your John Deere Mower is Leaking Gas

Cause	Reason for Problem	Solution
Dirty of Failed Carburetor	The carburetor can collect a buildup of substances remaining from old gas that can cause blockages or parts failures	Clean the carburetor and replace any damaged parts
Old Fuel Filter	Filter can become plugged	Replace fuel filter
Bad Fuel Pump	Pump can wear and deteriorate over time and may begin leaking at the seams	Replace the fuel pump
Bad Fuel Tank	A metal tank can develop a rust hole. A poly tank can leak at the seams of the tank.	Replace the fuel tank. Sometimes, a rust hole can be repaired if you can no longer find a replacement tank.
Bad Fuel Shut-Off Valve	Metal and plastic shut-off valves are prone to leaking	Replace the shut-off valve
Cracked Fuel Lines	Rubber fuel lines become dry and cracked causing gas to leak	Replace the fuel lines
Bad Seal in the Gas Cap	The gas cap seal can fail and no longer seal allowing gas to splash out of the fuel tank around the gas cap	Replace the gas cap

10. Mower Blades Won’t Engage or Turn On

You engage the PTO to power the blades and nothing happens. Your blades may not spin when deck components are worn, the PTO or safety switch is bad, the battery is weak, or the clutch is bad.

Detailed information can be found at:
John Deere Mower Blades Won’t Engage or Turn On

Cause	Reason for Problem	Solution
Worn deck belt	A worn belt won’t grip the pulleys to turn the blades.	Replace a worn belt.
Worn tensioner spring	The spring holds the idler pulleys in line. The spring can wear or fall off the mower.	Replace a worn or missing spring. Replace a worn tensioner bracket/arm.
Bad pulley bearing	A bad bearing can cause a pulley to seize or it can cause it to wobble causing the belt to roll off the pulley.	Replace a bad bearing in the pulley or replace the pulley assembly.
Faulty PTO switch	The switch fails to allow voltage from the battery to power the clutch.	Replace a bad PTO switch.
Bad clutch	A bad clutch will no longer transfer power from the engine to the blades.	Replace the clutch.
Worn clutch cable (manual clutch)	A worn cable, clutch lever, or linkages can wear failing to engage the clutch.	Replace the worn items.
Weak battery	The battery will not provide the power the clutch solenoid requires to engage the blades.	Charge a weak battery. Replace a battery that won’t hold a charge.
Bad safety switch	A bad safety switch may not allow the blades to engage as a safety measure.	Test and replace a bad switch.
Blown fuse	The fuse can blow to protect the electrical system.	Replace the fuse with a fuse with the same capacity. Consult a mechanic to find the root cause if you continue to blow the fuse.

11. Engine Overheats

When the engine smells hot, you must stop running the engine right away to avoid causing extensive engine damage.

Detailed information can be found at:
Reasons a John Deere Mower Engine Overheats

Cause	Reason for Problem	Solution
Wrong engine oil	Using the wrong oil for the ambient temperatures or oil not designed for air-cooled engines can cause the engine to run hot.	Drain the engine oil and fill it with fresh air-cooled engine oil with a viscosity that works best for outdoor temperatures.
Low engine oil level	Lack of lubrication causes increased friction and heat.	Change the engine oil and add fresh oil. Low oil may have caused engine damage that should be diagnosed by a small engine mechanic.
Plugged engine cooling fins	Plugged or damaged cooling fins are unable to move air to cool the cylinder heads and engine block.	Clean plugged cooling fins. Replace damaged fins.
Engine guard missing or out of place	The engine guard shields the engine to keep air circulating around the engine to keep it cool.	Securely attach the engine guard.
Plugged air filter	A very dirty air filter will starve the engine of air causing it to work harder to find air.	Replace the dirty air filter.
Mower deck full of debris	Engine work harder to turn blades through a deck full of debris.	Scrape the mower deck to remove debris.
Dull mower blades	Dull mower blades magnify the problem of a plugged deck.	Sharpen and Balance the mower blades.
Overworking the engine	Cutting long, wet, or thick grass can overwork the engine, especially when attempting more grass than the mower can handle at once.	Slow down to match your mowing conditions. Avoid cutting wet grass. Double or triple-cut an overgrown lawn.

12. Mower Clicks and Won’t Turn Over

Detailed information can be found at:
John Deere Clicks and Won’t Turn Over

Your John Deere may just be clicking and won’t turn over. This can happen when the mower or tractor has a bad battery, ground, starter solenoid, or starter motor.

In addition to checking these items, ensure the cables and wiring are securely attached, have good continuity, and are not corroded.

Cause	Reason for Problem	Solution
Damaged or Loose Battery Cables & Wiring	Loose or corroded wiring, cables, or terminals can prevent good conductivity.	Remove corrosion and replaced damaged components. Make sure wiring and cables are securely attached.
Weak or Bad Battery	A weak battery won’t provide the power needed to start and turn over the engine.	Test the battery and place it on a trickle charger if needed. Replace a battery that won’t hold a charge.
Bad Ground	The ground cable from the battery and the ground cable from the starter solenoid must make good contact and be free of corrosion. (A 3-post solenoid is self-grounded).	Remove any corrosion and make sure it is securely grounded to the mower.
Bad Starter Solenoid	The starter solenoid can fail and will no longer actuate to engage the starter motor.	Test the starter solenoid and replace it if faulty.
Bad Starter Motor	A bad starter motor will keep the motor from starting.	Replace the starter motor.