John Deere Z520a Problems

John Deere Z520a Problems

John Deere Z520A promises efficiency but sometimes leaves its users scratching their heads. From the unsettling vibrations caused by those pesky broken bolts to the uneven mowing that can make a lawn look more like a patchwork quilt, it’s clear that this lawnmower has its quirks. 

And let’s not forget the engine-related hiccups that can make it sound more like a grumbling old man than a powerful piece of machinery. But for every problem, there’s a solution waiting to be discovered. 

Dive in, as we unravel the mysteries of the Z520A and offer insights to make your mowing experience smoother.

Common John Deere Z520A Problems and Quick Fixes

One of the most common issues faced by John Deere Z520A owners is the mower cranking but not starting. 

This problem can be frustrating, especially when you’re ready to tackle your lawn chores. Let’s delve into the potential causes and their respective solutions.

1. Starting Issues

John Deere Z520a Starting Issues are being troubleshot by two friends.

Problem Analysis

  • Battery Issues: A weak or dead battery is often the primary culprit. If the mower cranks slowly or not at all, the battery might not have enough power to start the engine.
  • Spark Plug Malfunctions: The spark plug ignites the fuel in the combustion chamber. A faulty spark plug can prevent the mower from starting, even if it cranks.
  • Combustion Issues: For the engine to start, the air-fuel mixture in the combustion chamber must ignite. Problems related to fuel delivery or air intake can hinder this process.


  1. Battery Check and Replacement:
  • Inspection: Examine the battery for any visible damages or corrosion on the terminals.
  • Voltage Test: Use a multimeter to check the battery voltage. A reading below 12 volts indicates a weak battery.
  • Replacement: If the battery is old or fails the voltage test, consider replacing it with a new one.
  1. Spark Plug Maintenance
  • Visual Check: Remove the spark plug and inspect its tip. A sooty or oily spark plug can indicate combustion issues.
  • Cleaning: Use a wire brush to clean the spark plug tip. Ensure the gap setting is correct as per the mower’s manual.
  • Replacement: If the spark plug is damaged or has been in use for a long time, replace it with a new one.
  1. Addressing Combustion Issues
  • Fuel Inspection: Ensure the mower has fresh fuel. Old or contaminated fuel can prevent ignition.
  • Air Filter Check: A clogged air filter can restrict airflow to the combustion chamber. Clean or replace the air filter if necessary.
  • Carburetor Cleaning: Over time, the carburetor can get gummed up, affecting fuel delivery. Consider cleaning the carburetor or seeking professional help if you’re unsure.

 2. Transmission Concerns 

A John Deere Transmission Concerns is inspecting  in a warehouse.

Problems and Causes

  1. Sluggish Movement or Lack of Response: Some users have reported that the mower moves sluggishly or doesn’t respond well to controls. This can often be attributed to a worn-out transmission belt or issues with the hydrostatic drive system.
  1. Uneven Cutting: If the mower isn’t moving at a consistent speed, it can result in uneven cutting. This can be due to transmission fluid issues or clogs within the system.
  1. Difficulty in Shifting: Difficulty or stiffness when shifting between gears can indicate potential transmission wear or a lack of lubrication.
  1. Unusual Noises: Grinding or whining noises can be a sign of internal transmission damage or low transmission fluid levels.


  1. Regular Maintenance: Regularly check the transmission fluid levels and ensure they are at the recommended levels. Change the fluid at intervals suggested by the manufacturer. This not only ensures smooth operation but also prolongs the life of the transmission.
  1. Belt Inspection: Periodically inspect the transmission belt for signs of wear, cracks, or slack. Replace if necessary. A well-maintained belt ensures efficient power transfer from the engine to the transmission.
  1. Proper Mowing Techniques: Avoid mowing on extremely wet grass or overloading the mower. Such conditions can strain the transmission. Also, when mowing on slopes, move at a steady pace and avoid sudden changes in direction.
  1. Clean the Transmission Cooling Fins: Over time, grass clippings and debris can accumulate on the cooling fins of the transmission. Regular cleaning ensures efficient cooling and prevents overheating.
  1. Consult a Professional: If you notice persistent issues or unusual noises, it’s advisable to consult a professional or authorized service center. They can provide a comprehensive check and address internal issues that might not be easily visible.

3. Electrical System Issues 

Problem | Intermittent Electrical Failures

Some users have reported intermittent electrical failures, where the mower might suddenly stop or show signs of electrical disruptions during operation.


  • Wiring Inspection: Check the mower’s wiring for any signs of damage, wear, or loose connections. Ensure all connections are secure.
  • Fuse Check: Inspect the fuses. A blown fuse can lead to electrical disruptions. Replace any damaged fuses with ones of the correct rating.

Problem | Dimming or Flickering Lights

The lights on the John Deere Z520A might dim or flicker, indicating an issue with the electrical system.


  • Alternator Check: The alternator is responsible for powering the mower’s lights. Ensure it’s functioning correctly.
  • Battery Health: A weak battery can cause the lights to dim. Ensure the battery is in good health and fully charged.

Problem | Electrical Burn Smell

In some cases, users might notice a smell of burning plastic or rubber, indicating a potential electrical issue.


  • Immediate Shutdown: If you notice a burning smell, shut down the mower immediately. This could be a sign of overheating or a short circuit.
  • Inspection: Check the mower’s wiring, battery, and other electrical components for any signs of damage or burns. Seek professional help if necessary.

3. Hydrostatic Drive Problems

Problem | Loss of Drive Power

The mower may move slower than usual or might not move at all even when the engine is running.


  1. Check the hydrostatic fluid levels. Low fluid can lead to reduced power or complete loss of drive. Refill with the recommended hydraulic fluid if necessary.
  2. Inspect the drive belt for wear, damage, or slippage. Replace if needed.

Problem | Erratic Movement or Jerking

The mower might start, stop, or change speeds unpredictably.


  1. Air in the system can cause this. It’s recommended to purge the system of air. This can be done by jacking up the mower and running it at low speed in both forward and reverse.
  2. Ensure that the hydrostatic fluid is clean. Dirty or contaminated fluid can cause erratic behavior. Consider changing the fluid if it appears dirty.

Problem | Overheating

The mower gets excessively hot during operation, leading to a decrease in performance or shutdown.


  1. Ensure the cooling fins and the hydro fan are clean and free from debris. Overheating can occur if airflow is restricted.
  2. Check the hydrostatic fluid. Old or degraded fluid can lead to overheating. Replace with fresh fluid if necessary.

Problem | Noise from the Hydrostatic Drive

Unusual noises, such as whining or grinding, when the mower is in motion.


  1. This can be a sign of low hydrostatic fluid. Check the levels and refill if necessary.
  2. If the fluid is at the correct level but appears dirty or has a burnt smell, it might be time for a change.

User Feedback on Performance and Longevity

While the John Deere Z520A has faced its share of problems, many users have praised its performance, especially when maintained well. Its large fuel tank, impressive top speed, and ergonomic design have been highlighted as standout features. 

However, the importance of regular maintenance, seasonal checks, and using quality parts for replacements has been a consistent piece of advice from long-term users.

John Deere Z520A | Pros And Cons!

John Deere Z520A | Pros And Cons!
25 horsepower Kohler 2-cylinder, gasoline engine.Issues with the mower cranking but not starting have been reported.
Massive 26.5-liter (7 US gallon) fuel capacity.Some users have reported problems with fuses and the battery.
Top speed of 16 kph (10 mph).Malfunctions or inefficiencies in the hydrostatic system.
Options of 54-inch and 60-inch cutting widths.Overheating problems and oil leaks have been noted by some users.
Easy to operate even for extended periods.Challenges with the mower’s transmission affecting performance.
Suitable for large parks, gardens, and commercial spaces.Due to its size, power, and cost, it’s more suited for contractors than individual users.

Final Thoughts!

The John Deere Z520A, while a formidable machine in the realm of lawnmowers, isn’t without its challenges. A unique aspect often overlooked is the mower’s adaptability to various terrains, which can sometimes be a double-edged sword, leading to wear and tear if not used appropriately. 

From starting difficulties to transmission issues, users have faced a range of problems. However, with regular maintenance, understanding its capabilities, and addressing concerns promptly, many of these challenges can be overcome.

In essence, while the John Deere Z520A has its set of problems, its robust features and performance potential make it a worthy investment for those willing to invest time in its care.