5 Most Common Kubota ZD21 Problems With Their Solutions

The Kubota ZD21 is one of the most powerful and reliable mowers you will get your hands on in the industry. However, like any machine, the Kubota ZD21 users also face quite a few problems with the mower. 

What are the most common Kubota ZD21 problems? The problems typically include engine problems, blade issues, and so on. Problems with fuel, steering, and transmission are also common with the mower

In this article, we will explore these issues in detail, along with their proper solutions. On top of that, we will also discuss a few key points related to the topic!

A Short Solution Table of Kubota ZD21 Problems

There are quite a few problems that mower owners encounter with the Kubota ZD21. Here, we have prepared a table that includes the details of the problems and their solutions for a quick understanding. 

Problems CausesSolutions 
Starting ProblemsOld/Weak Battery
Faulty Starter Motor
Lack Of Fuel
Clogged Fuel Filters
Faulty Ignition Switch
Charge or replace the battery
Repair or install a new motor
Refill the tank
Clean the filters
Replace the ignition switch
Engine OverheatingLow Coolant Levels
Blocked Radiator
Worn Out Components
Refill the coolant
Clean or repair the radiator
Replace damaged parts
Blade ProblemsDull Blades
Uneven Cutting
Sharpen the blades
Adjust or change blades
Steering TroubleLow Power Steering Fluid
Stiff Components
Damaged Steering Linkage
Refill the tank properly
Ensure proper lubrication
Replace steering linkage
Transmission ProblemsOld Or Low Transmission Fluid
Blocked Transmission Filter
Change the fluid and fill the tank
Clean or replace the filters

Problems And Solutions Of Kubota ZD21

As we mentioned earlier, owners encounter quite a few issues with the Kubota ZD21 mower. Here, we will take a look at these problems and their appropriate solutions. 

1. Starting Problems

One of the most common issues that users face is starting problems. Oftentimes, the mower fails to start properly, which impacts the overall performance of the vehicle. It occurs due to several reasons including- 

a) Old/Weak Battery

The battery is a crucial part of a vehicle. Over time, the batteries lose their efficiency and performance. This causes the battery to require more frequent charging as it drains more quickly. If dirt, debris, etc., accumulates in the battery terminals, it can also prevent the component from working properly. 


Check the battery connected to the vehicle and ensure that it is working properly or not. If the battery is weak and old, make sure to replace it with a new one. Inspect the terminals connected to the battery and clean them with a wire brush if they have accumulated dust, dirt, etc. 

b) Faulty Starter Motor

Problems with a starter motor will cause starting issues with the Kubota ZD21. When turning the key, look for a clicking sound. If the vehicle makes a clicking sound, the starter motor is faulty. 


Examine the starter motor properly and make sure that it is in proper working condition. If there are any worn-out parts, repair or replace the parts. In case the motor is broken, you can replace the entire starter motor without much hassle. 

c) Lack Of Fuel

For a vehicle to start and operate, it requires a minimum amount of fuel in the tank. If the fuel present is lower than the minimum threshold, the mower will not start properly. Not only that, but unclean fuel can also cause problems. 


Keep an eye on the amount of fuel present in the tank. Refill the tank with fuel up to the recommended level. And make sure that the fuel is clean and there is no water present. Additionally, drain the fuel and refill the tank if the fuel is old or dirty. 

d) Clogged Fuel Filters

Fuel filters help to prevent contaminants in the fuel from reaching the engine. Over time, the filters get clogged due to dirt, debris, and so on. When this happens, the flow of fuel will be restricted, preventing the engine from starting properly. 


Turn the vehicle off and take out the fuel filters. Clean the filters properly to remove dirt, debris, dust, etc., on a regular basis. Make sure to replace the filters with new ones every 3 to 4 months. 

e) Faulty Ignition Switch

The vehicle will not be able to start and run without an ignition switch. If the ignition switch fails to send signals to the engine, the mower will not start. 


Examine the ignition switch and its connection to the engine to ensure that it is working properly. If the switch is faulty, you will have to replace it with a new one. 

2. Engine Overheating

Engine overheating in the Kubota ZD21 occurs due to several reasons. These reasons include low coolant levels, blocked radiators, and many more. Let’s break down them in detail. 

a) Low Coolant Levels

Ensuring the right amount of coolant in the system helps to regulate the temperature properly, allowing the engine to operate smoothly. If the coolant level is low, it will not regulate the temperature and cause the engine to overheat. 


Examine the coolant level in the system and ensure that it is at the recommended level. If the coolant level is low, refill the tank, and do not forget to rely on the right coolant for the engine. 

b) Blocked Radiator

Over time, the radiator gets clogged due to the accumulation of dirt, debris, and other pollutants. When the problem arises, the coolant cannot move freely through the system, which prevents the temperature from regulating. As a result, the engine will overheat significantly and cause damage. 


Turn off the vehicle and let the engine cool down properly. Examine the radiator and see whether it is clogged or not. Get rid of the dirt, debris, etc., with the help of a soft brush and secure it back in place. If there are any worn or damaged components, repair or replace the radiator

c) Worn-Out Components

There are several components that are connected to the engine. These components are the thermostat, belt, fan, and so on. Over time, these components get damaged due to wear and tear. This causes the parts to lose their functionality, causing the engine to overheat. 


Check all the components connected to the system and make sure that all of them are working properly. If any of the components are worn out or damaged, take necessary actions to replace or repair them. 

3. Blade Problems 

The blade is one of the most crucial parts of a mower. Without a properly functional blade, you will not be able to cut grass properly. Take a look at the problems and solutions behind the blade issues. 

a) Dull Blades 

Fast cutting is one of the top requirements of a mower. Over time, the blade loses its sharpness and becomes dull. Not only that but rust or corrosion also causes the blade to lose its edge. 


Check the blade and see whether it is working perfectly or not. If the blade is dull, sharpen it at home or get it done by a professional. In case the blade is rusted, you will have to replace the old blade with a new one. 

b) Uneven Cutting

Uneven grass on your lawn makes the exterior lose its beauty and appealing look. However, uneven cutting is often caused due to blade damage and imbalance. The blade often becomes damaged or gets chipped away. Additionally, the blade loses balance which results in uneven cutting. 


Check the blade connected to the mower and ensure whether it is damaged or not. Purchase a new one and replace the old blade if it is damaged or cracked. If the blade is unbalanced, you will have to balance it with the help of a balancer to ensure even cutting. 

4. Steering Trouble 

Being able to handle the mower and steer it properly is important to ensure an even pattern or cut on the lawn. Problems with lubrication, steering gear, etc cause trouble when steering the Kubota ZD21. See the problems in detail, along with their solutions. 

a) Low Power Steering Fluid 

Power steering fluid is essential to make sure that the steering of the vehicle works efficiently at all times. Oftentimes, the steering fluid decreases than the required level. As a result, the steering of the mower is affected. 


Check the power steering fluid present in the tank and ensure that it is at the recommended level. If it is lower than the required mark, refill the tank to ensure smooth steering. 

b) Stiff Components

For smooth and proper steering performance, all the required components must move freely. Over time, the parts lose lubrication which causes the components to become stiff. This results in faster wear or tear damage of the parts and pieces. 


Examine all the components connected to the system and make sure that they are properly lubricated. If the parts are not lubricated, then use suitable lubrication for the components. This will allow the components to move freely and reduce the risk of wear or tear. 

c) Damaged Steering Linkage

The steering linkage of the vehicle connects the steering wheel to the gears in order to control the tires. However, if the linkage is damaged or loose from its place, it will prevent the wheels from getting the right signals. 


Inspect the steering linkage in the mower and ensure that it is in proper working condition. If the linkage is loose, tighten it with a proper tool. You will have to replace the steering linkage in case it is damaged. 

5. Transmission Problems 

Without a properly functioning transmission, a mower will not be able to work properly. If you are facing issues with the transmission of your vehicle, there are quite a few potential reasons behind it.

a) Old Or Low Transmission Fluid 

In order to function perfectly, the transmission requires a certain amount of fluid. If the fluid is lower than its required threshold, the transmission will not perform properly. 

In case the transmission is in the system for a long, it accumulates dirt, dust, etc., which makes the fluid unclean. This can also hamper transmission performance. 


Check the transmission fluid level and ensure it is up to the mark. Refill the tank if the fluid is low. If the fluid is old and dirty, drain it completely and fill the tank again. Make sure to use the right type of transmission fluid for optimal performance. 

b) Blocked Transmission Filter 

The work of the transmission filter is to keep the contaminants away from the system. However, the filters get blocked as pollutants accumulate, restricting the flow of transmission fluids. In cases like these, the system will not perform properly and result in transmission problems. 


Turn the engine off and let it cool properly. Inspect the filters connected to the system and clean them properly. If the filters are rusted or severely clogged, replace them with new filters. 


The Kubota ZD21 is an extraordinary mower available in the industry. Its outstanding performance and sheer cutting have made it a popular choice among people. However, the Kubota ZD21 problems are quite common and can be solved easily within a few steps. 

Whenever you encounter any of the problems mentioned above, feel free to take help from this guide. But if the problem persists, make sure to contact a professional for proper diagnosis and guidance.

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