Kubota GZD21-HD User Manual (English)

Questions and Answers:

M
Miranda HowardAug 9, 2025
Why is my Kubota Lawn Mower engine difficult to start?
- B
  brownryanAug 9, 2025
  Difficulty starting your Kubota Lawn Mower engine can stem from several causes: a lack of fuel flow (check the fuel tank and filter, replacing the filter if needed), air or water in the fuel system (ensure the fuel line coupler bolt and nut are tight, bleed the fuel system), increased oil viscosity in winter (use oils with different viscosities based on ambient temperatures), or a weak battery (clean battery cables and terminals, charge the battery, and in cold weather, remove, charge, and store the battery indoors, installing it only when use is imminent).
G
grayamberAug 16, 2025
What to do if my Kubota GZD21-HD Lawn Mower engine overheats?
- C
  Christina EstradaAug 16, 2025
  If your Kubota Lawn Mower engine overheats, it could be due to several reasons. The engine might be overloaded, in which case you should lower the speed or reduce the load. Alternatively, the coolant level might be low, requiring you to fill the cooling system to the correct level and check for leaks in the radiator and hoses. A loose or defective fan belt could also be the culprit, necessitating adjustment or replacement. A dirty radiator core or grille screens can impede cooling, so remove any debris. Finally, a corroded coolant flow route may be the issue, in which case you should flush the cooling system.
J
Justin WellsAug 22, 2025
What to do if my Kubota Lawn Mower engine stops suddenly?
- M
  Manuel GonzalezAug 22, 2025
  If your Kubota Lawn Mower engine stops suddenly, it is likely due to insufficient fuel. Refuel the lawn mower. If the problem persists, bleed the fuel system.
S
Susan BurkeAug 28, 2025
Why does my Kubota Lawn Mower have insufficient engine power?
- C
  Carmen CarrollAug 28, 2025
  Insufficient engine power in your Kubota Lawn Mower can be caused by insufficient or dirty fuel. Check the fuel system. It can also be caused by a clogged air cleaner. Clean the element.
J
Jamie WilliamsSep 2, 2025
Why are exhaust fumes colored on my Kubota Lawn Mower?
- O
  opatrickSep 2, 2025
  Colored exhaust fumes from your Kubota Lawn Mower can indicate different issues. Black fumes suggest you should change the fuel and fuel filter, check the oil level, and reduce the engine load. Blue-white fumes suggest you should heat the muffler by applying load to the engine, check the injection nozzle, and change the fuel and fuel filter.

Kubota GZD21-HD Specifications

General

Brand	Kubota
Model	GZD21-HD
Category	Lawn Mower
Language	English

Summary

OPERATOR'S MANUAL

Foreword and Safety Introduction

Safety First - Hazard Levels

Explains the primary safety symbol and defines hazard levels (Danger, Warning, Caution).

Safe Operation Overview

Mower Mounting Procedures

Operating the Engine

Covers starting, checking, and stopping the engine safely.

Operating the Machine General

Operating the Mower Function

Maintenance and Periodic Service

Service Intervals Schedule

Schedule of recommended maintenance tasks based on operating hours.

Lubricants, Fuel, and Coolant Specs

Daily Check Procedures

Routine checks to perform before operating the machine.

Safe Operation - General Precautions

General Safety Precautions

Essential safety guidelines for operating the mower and preventing injury.

Before Operating Checklist

Key checks and preparations required before starting the machine.

Safe Operation - Starting and Working

Safe Working Practices

Operational guidelines and safety during machine use.

Safety Regarding Children

Safety considerations and precautions related to children.

Safe Operation - Slopes and Stopping

Operator Age and Slope Safety

Safety considerations for operators and operating on slopes.

Slope Operation Guidelines

Recommended and prohibited actions for safe operation on slopes.

Safe Operation - Servicing, Fuel, and Battery

Servicing Safety Precautions

Safety precautions to follow during maintenance activities.

Fuel Handling Safety

Safe practices and precautions for handling fuel.

Jump Starting Safety Guidelines

Safety guidelines for jump starting the machine's battery.

Battery Safety Precautions

Precautions for handling and charging the battery.

Safe Operation - Safety Labels

Pictorial Safety Labels Identification

Identification of important safety labels located on the machine.

Servicing of Machine - Identification

Servicing of Machine - Serial Number Recording

Instrument Panel and Controls - Overview

Motion Control Lever Operation

Instrument Panel and Controls - Gauges and Levers

Mower Mounting - Initial Setup

Mounting the Mower Deck

Step-by-step guide to attach the mower deck to the tractor.

Operating the Engine - Starting

Starting the Engine Safely

Step-by-step guide to safely start the engine.

Operating the Engine - Controls and Ignition

Key Switch Operation

Operating the Engine - Starting and Warm-up

Preheating and Starting Procedure

Steps for preheating the engine and initiating the start sequence.

Operating the Engine - Checks During Operation

Checks During Operation

Monitoring machine status while running for normal operation.

Immediate Engine Stop Conditions

Conditions requiring immediate engine shutdown to prevent damage.

Engine Overheating Precautions

Steps to take if the engine overheats to prevent damage.

Operating the Engine - Cold Weather, Jump Start, and Warm-up

Cold Weather Starting Procedures

Engine Warming Up Importance

Jump Starting Procedure

Safe procedure for jump starting the machine's battery.

Operating the Engine - Stopping and Jump Start Details

Jump Starting Cable Connections

Detailed steps for connecting jumper cables safely.

Stopping the Engine Safely

Operating the Machine - New Machine Procedures

Operating a New Machine

Operating the Machine - Operator Position and Implement Control

Hydraulic Lift Pedal Operation

Operating the Machine - Speed and Direction Control

Motion Control Lever Operation

Safe use of motion control levers for driving and steering.

Operating the Machine - Motion Control Lever Details

Neutral Lock Position Importance

Forward and Reverse Motion

Re-starting on Slopes Safely

Safe procedure for restarting the machine on inclines.

Operating the Machine - Maneuvering Techniques

Operating the Machine - Stopping and Parking

Stopping the Machine Safely

Parking Procedures Safely

Operating the Machine - Transport

Transporting the Machine Safely

Periodic Service - Checks and Safety Devices

Safety Devices Functionality

Importance and checking of safety devices before operation.

Periodic Service - Safety Device Tests and Air Cleaner

Safety Device Tests Procedure

Detailed tests for safety systems like seat and PTO switches.

Periodic Service - Gear Box Oil Level

Periodic Service - PTO Case Oil and Greasing

Periodic Service - Lubrication Points (Joints)

Periodic Service - Oiling Points

Periodic Service - More Oiling Points

Periodic Service - Battery Check and Charging

Checking Battery Condition

Battery Charging Safety

Periodic Service - Battery Storage and 100 Hour Maintenance

Battery Charging and Storage

100 Hour Service: Engine Oil Change

Steps for changing the engine oil at 100-hour intervals.

Periodic Service - Engine Oil and Fuel System Checks

100 Hour Service: Engine Oil Change (Cont.)

Completing the engine oil change procedure.

Checking Fuel Lines and Fuel Filter

Periodic Service - Belts and Brakes

Checking Parking Brake Adjustment

Periodic Service - 150 Hour Maintenance

150 Hour Service: Gear Box Oil Change

Procedure for changing the gear box oil at 150-hour intervals.

Periodic Service - 200 Hour Maintenance

200 Hour Service: Engine Oil Filter Replacement

Steps to replace the engine oil filter at 200-hour intervals.

200 Hour Service: Transmission Fluid Change

Procedure for changing transmission and rear axle fluid.

Periodic Service - Transmission Fluid (Continued)

200 Hour Service: Transmission Fluid Change (Cont.)

Completing the transmission fluid change procedure.

Periodic Service - Transmission Oil Filter and Strainer

Replacing Transmission Oil Filter

Steps to replace the transmission oil filter.

Periodic Service - Hoses and Axle Pivot

Periodic Service - Caster, Air Line, Fuel Filter, Air Cleaner, Coolant

400 Hour Service: Fuel Filter Replacement

Procedure for replacing the fuel filter at 400-hour intervals.

1 Year Service: Air Cleaner Element Replacement

Procedure for replacing the air cleaner element annually.

Flushing Cooling System and Changing Coolant

Steps for flushing the cooling system and changing the coolant.

Periodic Service - Coolant and Anti-freeze

Coolant and Anti-freeze Mixture

Periodic Service - 2 Year Maintenance

2 Year Service: Hydraulic Hose Replacement

Replacing hydraulic hoses every 2 years or if damaged.

2 Year Service: Fuel Lines Replacement

Replacing fuel lines every 2 years or if damaged.

2 Year Service: Engine Breather Hose Replacement

Replacing the engine breather hose.

2 Year Service: Radiator Hose Replacement

Replacing radiator hoses every 2 years or if damaged.

2 Year Service: Mower Gear Box Oil-Seal Replacement

Replacing the mower gear box oil seal.

2 Year Service: Intake Air Line Replacement

Replacing the intake air line.

Periodic Service - Service As Required

Service As Required: Fuse Replacement

Steps for replacing blown fuses in the machine.

Checking and Replacing Blades

Inspecting and replacing mower blades for cutting performance.

Periodic Service - Blade Replacement Details

Blade Replacement Procedure

Procedure for replacing mower blades, including bolt torque.

Periodic Service - Blade Replacement by Model

Blade Replacement (GZD21 Models)

Replacing mower blades for GZD21 models.

Blade Replacement (RCK48 Models)

Replacing mower blades for RCK48 models.

Periodic Service - Mower Belt Replacement (GZD15)

Mower Belt Replacement (GZD15)

Replacing mower belts for GZD15 models.

Periodic Service - Mower Belt Replacement (GZD21)

Mower Belt Replacement (GZD21)

Replacing mower belts for GZD21 models.

Periodic Service - Fuel System

Bleeding Fuel System

Procedure to remove air from the fuel system.

Adjustment - Motion Control and HST Neutral

Motion Control Lever Adjustment

HST Neutral Adjustment

Adjusting the hydrostatic neutral position for safety.

Adjustment - Lever Positions

Reverse Return Position Adjustment

Motion Control Lever Alignment

Adjustment - Control Levers and Mower Deck Leveling

Aligning the Control Levers

Mower Deck Leveling Overview

Side-to-Side Mower Deck Leveling

Adjusting mower deck for side-to-side level.

Adjustment - Mower Deck Leveling Details

Side-to-Side Mower Deck Leveling (Cont.)

Detailed steps for side-to-side mower deck adjustment.

Front-to-Rear Mower Deck Leveling

Adjusting mower deck for front-to-rear level.

Adjustment - Mower Deck Leveling (Front-to-Rear)

Front-to-Rear Mower Deck Leveling (Cont.)

Detailed steps for front-to-rear mower deck adjustment.

Adjustment - Torque Specifications

General Torque Specification

Adjustment - Tightening Torque Chart

Tightening Torque Chart Details

Troubleshooting - Engine Issues

Engine Troubleshooting Guide

Diagnosing and fixing engine problems and their causes.

Troubleshooting - Battery and Machine Issues

Battery Troubleshooting Guide

Diagnosing and fixing battery issues and their causes.

Machine Troubleshooting Guide

Troubleshooting - Mower Issues

Mower Troubleshooting Guide

Diagnosing and fixing mower-related issues and their causes.

Troubleshooting - Grass Catcher Issues

Grass Catcher Troubleshooting Guide

Diagnosing and fixing grass catcher problems and their causes.

Related product manuals

Kubota GZD21-HD User Manual

Table of Contents

Questions and Answers:

Kubota GZD21-HD Specifications

Summary

OPERATOR'S MANUAL

Foreword and Safety Introduction

Safety First - Hazard Levels

Safe Operation Overview

Mower Mounting Procedures

Operating the Engine

Operating the Machine General

Operating the Mower Function

Maintenance and Periodic Service

Service Intervals Schedule

Lubricants, Fuel, and Coolant Specs

Daily Check Procedures

Safe Operation - General Precautions

General Safety Precautions

Before Operating Checklist

Safe Operation - Starting and Working

Safe Working Practices

Safety Regarding Children

Safe Operation - Slopes and Stopping

Operator Age and Slope Safety

Slope Operation Guidelines

Safe Operation - Servicing, Fuel, and Battery

Servicing Safety Precautions

Fuel Handling Safety

Jump Starting Safety Guidelines

Battery Safety Precautions

Safe Operation - Safety Labels

Pictorial Safety Labels Identification

Servicing of Machine - Identification

Servicing of Machine - Serial Number Recording

Instrument Panel and Controls - Overview

Motion Control Lever Operation

Instrument Panel and Controls - Gauges and Levers

Mower Mounting - Initial Setup

Mounting the Mower Deck

Operating the Engine - Starting

Starting the Engine Safely

Operating the Engine - Controls and Ignition

Key Switch Operation

Operating the Engine - Starting and Warm-up

Preheating and Starting Procedure

Operating the Engine - Checks During Operation

Checks During Operation

Immediate Engine Stop Conditions

Engine Overheating Precautions

Operating the Engine - Cold Weather, Jump Start, and Warm-up

Cold Weather Starting Procedures

Engine Warming Up Importance

Jump Starting Procedure

Operating the Engine - Stopping and Jump Start Details

Jump Starting Cable Connections

Stopping the Engine Safely

Operating the Machine - New Machine Procedures

Operating a New Machine

Operating the Machine - Operator Position and Implement Control

Hydraulic Lift Pedal Operation

Operating the Machine - Speed and Direction Control

Motion Control Lever Operation

Operating the Machine - Motion Control Lever Details

Neutral Lock Position Importance

Forward and Reverse Motion

Re-starting on Slopes Safely

Operating the Machine - Maneuvering Techniques

Operating the Machine - Stopping and Parking

Stopping the Machine Safely

Parking Procedures Safely

Operating the Machine - Transport

Transporting the Machine Safely

Periodic Service - Checks and Safety Devices

Safety Devices Functionality

Periodic Service - Safety Device Tests and Air Cleaner

Safety Device Tests Procedure

Periodic Service - Gear Box Oil Level

Periodic Service - PTO Case Oil and Greasing

Periodic Service - Lubrication Points (Joints)