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9 Common John Deere Lawn Mower Problems & Solutions

No matter what brand of lawn mower you have, when you own it long enough, you will run into problems that will need to be repaired to ensure your mower 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 issues common to running lawn mowers and how to solve these issues. You will find links that provide more in-depth information on each problem including troubleshooting steps.

The most common John Deere lawn mower problems are:

  • John Deere doesn’t start
  • John Deere dies while mowing
  • John Deere is smoking
  • John Deere has a weak hydrostatic transmission
  • John Deere won’t drive straight or steer correctly
  • John Deere won’t move
  • John Deere is shaking or vibrating
  • John Deere is cutting uneven
  • John Deere is leaking gas
Tools to find your John Deere mower problems and solutions

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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.

10 Common John Deere Problems & Solutions

John Deere Mower Problem 1: Mower Won’t Start

When your John Deere mower 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

CauseReason for ProblemSolution
No gas in the fuel tankFuel tank is emptyFill with fresh fuel
Bad or old fuelFuel breaks down overtime making your fuel less efficient and prone to clogging the fuel systemDrain 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 capThe vent in the cap can get clogged causing your tank to form a vacuum restricting fuel flowUse a thin piece of wire to try to clear the clogged vent. Replace the cap if needed.
Bad spark plugExcessively dirty or broken spark plug; bad connection; not gapped correctlyReplace with a new spark plug, secure connections, and ensure it is gapped to manufacturer specifications
Plugged air filterDirt and grass can plug the air filter preventing airflowRemove the filter and clean it. Replace the filter if it is in bad condition.
Plugged fuel filterA dirty fuel filter will restrict fuel flowReplace the fuel filter
Bad fuel pumpA failed or leaking fuel pump will no longer create the pressure needed to pump fuelReplace the fuel pump
Blocked fuel linesBad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuelUse a carb cleaner and compressed air to clear the clog out of the fuel line. Replace the line if necessary.
Dirty carburetorThe carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flowClean the components making up the carburetor. Replace if needed.
Bad battery or loose & dirty terminalsA dead battery, loose cables, or corroded terminals can cause starting problemsCharge 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 switchSafety 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 coilYour mower will not start when either the ignition switch or coil is badTest and replace a bad switch
Broken recoilA pull start mower may have a damaged or broken recoil preventing the recoil to initiate starting your engineCheck 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.
Reasons Your John Deere Mower Won’t Start

John Deere Mower Problem 2: Mower 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

CauseReason for ProblemSolution
Bad fuelFuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system and engine damageDrain 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 filterDirt and grass can plug the air filter preventing airflowRemove the filter and clean it. Replace the filter if it is in bad condition.
Dirty or broken cooling finsCooling fins get packed with dirt, oil, and grass not allowing air to effectively cool the engine blockReplace broken fins and clean the cooling fins.
Clogged fuel lines or filterBad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuelUse a carb cleaner and compressed air to clear the clog out of the fuel line. Replace a plugged fuel filter.
Dirty carburetorThe carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flowClean all components making up the carburetor. Replace if needed.
Too Much Engine OilToo much engine oil increases pressure in the crankcase causing it to overheat and dieCorrect your engine oil level by removing a little oil
Bad Spark PlugDirty 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 CoilA windings on the coil can separate and short out a bad ignition coilCheck for a break in the continuity using an ohm meter and replace is found bad
Choke is in the Wrong PositionA 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 CapGas 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 DeckA clogged mower deck causes a strain on the engine causing it to work hard and possibly shut downPeriodically scrape your mower deck to keep it clean
Reasons Why Your John Deere Mower Dies While Mowing

John Deere Mower Problem 3: Lawn 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

CauseReason for ProblemSolution
Plugged air filterDirt and grass can plug the air filter preventing airflowRemove the filter and clean it. Replace the filter if it is in bad condition.
Too much oil in the crankcaseExcessive oil can cause pressure to build in the engine allowing oil to get into the cylinder through the valve trainDrain a little engine oil until it is at the manufacturer’s recommended oil level.
Engine oil level is too lowLack 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 gasketInternal 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
Reasons Why Your John Deere Mower is Smoking

John Deere Mower Problem 4: Weak Hydrostatic Transmission 

CauseReason for ProblemSolution
Bad drive beltA bad drive belt can cause your pump not to work efficientlyReplace a frayed, cracked, or worn belt
Bad tensioner pulleyWhen a tensioner pulley fails, it fails to keep tension on the drive beltReplace the pulley and grease the tensioner arm
Low or old hydraulic oilLow or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weakChange 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).
Reasons Why Your John Deere Mower’s Hydrostatic Transmission Seems Weak

John Deere Mower Problem 5: Mower 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.

CauseReason for ProblemSolution
Incorrect tire pressureUnequal 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 turnBad dampers will cause your mower to jerk to one side when moving forwardReplace with a new damper
Tracking adjustment needed on zero turnWhen one tire is moving faster than the other, your mower can pull to one sideAdjust 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 mowerWorn bushings, washers, and gears can cause your mower to not steer one way or the otherInspect and replace the parts that failed on your steering system
Reasons Why Your Mower Won’t Drive Straight or Steer Correctly

John Deere Mower Problem 6: Lawn Mower Won’t Move

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

CauseReason for ProblemSolution
Drive release lever in the wrong positionThe drive release lever allows hydrostatic mowers to roll freelyThe drive release lever must be in the operating position.
Missing key in the axleYour riding mower may have a small key in the axle that may have fallen out of placeReplace the key in the axle
Drive pump belt is wornThe 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 pulleyThe bearing in the tensioner pulley can failReplace the tensioner pulley
Missing idler arm springIf the idler arm spring breaks or goes missing, it can no longer place tension on the drive beltReplace the broken or missing spring
Low or old hydraulic oilLow or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weakChange 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 fluidHot hydraulic fluid can be a sign of damage to your hydrostatic transmission systemLet 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 systemAir must be bled from the hydraulic system after changing your hydraulic fluid or the mower will not be able to move at normal speedsFollow John Deere’s procedures for changing the hydraulic fluid and bleeding air from the system in your owner’s manual.
Reasons Why Your John Deere Will Not Move or Go Forward

John Deere Mower Problem 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

CauseReason for ProblemSolution
Loose or missing engine mounting boltsEngine bolts are used to reduce the vibration of the mower when the engine is runningSecure engine bolts and replace any missing bolts
Clutch is badWhen 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 bladesDamaged and unbalanced blades can send a vibration through your mower. Blades must be balanced before installingReplace any damaged blades and make sure they are balanced.
Material wrapped around the blade spindleForeign materials like string or long weeds can get wrapped around your blade shaft causing vibrationRemove all debris and items wrapped around the blade shaft. Check for spindle damage.
Bad spindle housing bearingsVibration 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 beltCheck deck belt and pulleys for wearing of the belt and bearing failure in the pulleysReplace any damaged or worn belts and pulleys
Debris lodged in mowerThe 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.
Reasons Your John Deere Mower is Vibrating

John Deere Mower Problem 8: Mower 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 bladeUneven tire pressuresEngine speed is too low
Bent mower bladeUnleveled mower deckGround speed is too fast
Blade installed wrongBent blade spindle or spindle bearingDamaged deck shell
Clogged Mower DeckWorn deck pulleys or beltOperator error
Reasons Your John Deere Mower is Cutting Uneven

John Deere Mower Problem 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

CauseReason for ProblemSolution
Dirty of Failed CarburetorThe carburetor can collect a buildup of substances remaining from old gas that can cause blockages or parts failuresClean the carburetor and replace any damaged parts
Old Fuel FilterFilter can become pluggedReplace fuel filter
Bad Fuel PumpPump can wear and deteriorate over time and may begin leaking at the seamsReplace the fuel pump
Bad Fuel TankA 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 ValveMetal and plastic shut-off valves are prone to leakingReplace the shut-off valve
Cracked Fuel LinesRubber fuel lines become dry and cracked causing gas to leakReplace the fuel lines
Bad Seal in the Gas CapThe gas cap seal can fail and no longer seal allowing gas to splash out of the fuel tank around the gas capReplace the gas cap
Places Your John Deere Mower May Be Leaking Gas