John Deere Riding Mower Problems | Repair Guide

John Deere makes some of the most popular riding mowers in America. The 100 Series and X Series tractors are built to last, but they still develop problems over time. This guide covers common issues across John Deere’s residential lineup.

Table of Contents

• Model Overview
• Starting Problems
• Engine Issues
• Transmission Problems
• Deck and Cutting
• Electrical Issues

Model Overview

John Deere’s residential riding mowers fall into several series.

100 Series (Entry Level)

Model	Engine	Deck	Transmission
S100	Briggs 17.5HP	42”	Hydrostatic
S110	Briggs 19.5HP	42”	Hydrostatic
S120	Briggs 22HP	42”	Hydrostatic
S130	Briggs 22HP	42”	Hydrostatic
S140	Briggs 22HP	48”	Hydrostatic
S160	Briggs 24HP	48”	Hydrostatic
S180	Briggs 24HP	54”	Hydrostatic

E Series (Value)

Model	Engine	Deck
E100	Briggs 17.5HP	42”
E110	Briggs 19HP	42”
E120	Briggs 20HP	42”
E130	Briggs 22HP	42”
E140	Briggs 22HP	48”

X Series (Premium)

Model	Engine	Deck
X350	Kawasaki 18.5HP	42”/48”
X370	Kawasaki 22HP	42”/48”
X380	Kawasaki 22HP	48”/54”
X390	Kawasaki 22HP	48”/54”

[NEED REAL IMAGE: John Deere model number location]

Starting Problems

Won’t Crank

The starter doesn’t turn the engine at all.

Safety switches: John Deere mowers have multiple safety interlocks.

• Seat switch - must be occupied
• Brake switch - brake must be engaged
• Blade switch - blades must be disengaged
• Neutral switch - trans must be in neutral

Test safety switches:

1. Sit on seat
2. Engage parking brake
3. Disengage blades
4. Try starting

Battery issues:

• Check voltage (should be 12.5V+)
• Clean terminals
• Load test battery
• Check charging system

Cranks But Won’t Start

Fuel system check:

1. Fresh fuel? Gas older than 30 days is suspect
2. Fuel shutoff open?
3. Fuel pump working? (Check pulse line)
4. Fuel filter clean?
5. Carburetor getting fuel?

Spark check:

1. Remove spark plug
2. Ground against engine
3. Crank and look for spark
4. No spark = coil or safety switch

Compression check: Normal: 60-90 PSI Low compression = engine wear

[NEED REAL IMAGE: John Deere fuel shutoff valve]

Hard Starting

When cold:

• Choke not engaging
• Fuel delivery slow
• Weak battery

When hot:

• Vapor lock from engine heat
• Ignition coil failing
• Carburetor percolation

Key Switch Problems

John Deere key switches can fail.

Symptoms:

• No response when turning key
• Intermittent starting
• Engine dies when key released

Test: Check for 12V at starter solenoid when key turned. No voltage = switch or wiring.

Engine Issues

Engine Surging

RPM rises and falls repeatedly.

Common causes:

1. Dirty air filter (check first)
2. Carburetor needs cleaning
3. Governor linkage binding
4. Fuel delivery issue

John Deere specific: The foam pre-cleaner filter clogs quickly. Clean or replace it.

Loss of Power

Engine runs but lacks power.

Check:

• Air filter condition
• Spark plug condition
• Fuel delivery
• Compression
• Exhaust restriction

Mowing related: Blades dull or deck clogged reduces cutting efficiency and loads engine.

Overheating

Engine shuts down from heat.

Causes:

• Cooling fins clogged
• Engine shroud missing or damaged
• Low oil
• Overworking engine

Prevention: Clean cooling fins and shroud regularly. Don’t mow at lowest setting in thick grass.

Oil Leaks

Common locations:

• Valve cover gasket
• Oil drain plug
• Oil filter gasket
• Crankcase gasket

Valve cover fix: Simple gasket replacement. Torque bolts to spec.

[NEED REAL IMAGE: John Deere engine oil leak locations]

Transmission Problems

Hydrostatic Transmission Basics

100 Series mowers use Tuff Torq hydrostatic transmissions.

How it works: Hydraulic pump and motor provide variable speed without shifting.

Won’t Move

Mower runs but doesn’t drive.

Check:

1. Bypass valve - must be closed for normal operation
2. Drive belt condition
3. Drive belt tension
4. Transmission engagement

Bypass valve: Located at rear of mower. Used for pushing mower when engine off. Make sure it’s closed.

Slow or Weak

Drive feels weak or slower than normal.

Causes:

• Low transmission fluid
• Drive belt slipping
• Internal transmission wear
• Air in hydraulic system

Fluid check: Most 100 Series use maintenance-free trans. X Series may have serviceable fluid.

Jerky Movement

Transmission engages roughly.

Causes:

• Control linkage binding
• Internal valve wear
• Air in system
• Pedal adjustment

Transmission Replacement

When internal components fail, replacement is typically required.

Cost: $400-800 for transmission Labor: 2-4 hours

For mowers over 8-10 years old, consider total mower replacement vs expensive trans repair.

[NEED REAL IMAGE: John Deere transmission bypass valve]

Deck and Cutting Issues

Uneven Cut

One side cuts lower than the other.

Check:

1. Tire pressure - must be equal on both sides
2. Deck level adjustment
3. Blade condition - bent or uneven wear
4. Spindle bearings

Deck leveling:

1. Park on flat surface
2. Check blade height at front and sides
3. Adjust deck hangers as needed
4. Recheck after adjustment

Blades Won’t Engage

PTO switch doesn’t activate blades.

Electrical:

• Check PTO switch operation
• Check blade engagement fuse
• Test clutch solenoid

Mechanical:

• Belt broken or off
• Clutch failure
• Safety switch triggered

Poor Cut Quality

Grass looks ragged after mowing.

Causes:

• Dull blades (most common)
• Deck buildup restricting airflow
• Mowing too fast
• Deck set too low for conditions

Fix:

1. Sharpen or replace blades
2. Clean deck underside thoroughly
3. Slow down
4. Raise deck height

Deck Vibration

Excessive shaking from deck area.

Causes:

• Bent blade
• Blade bolt loose
• Spindle bearing failure
• Deck belt worn

Test spindles: With engine off and belt removed, spin each blade by hand. Should turn smoothly without wobble or noise.

[NEED REAL IMAGE: John Deere deck spindle inspection]

Electrical Issues

Battery Drains

Battery goes dead between uses.

Causes:

• Charging system failure
• Parasitic drain
• Old battery
• Loose connections

Test charging: With engine running, battery should show 13.5-14.5V. Below 13V = charging problem.

Charging System

Components:

• Alternator (under flywheel)
• Voltage regulator
• Wiring and connections

Testing:

1. Check voltage at battery (engine running)
2. Should be 13.5-14.5V
3. No increase = alternator or regulator

Fuse Locations

John Deere 100 Series fuses are under the hood.

Common fuses:

• 20A main
• 15A PTO
• 10A ignition
• 7.5A accessories

Check fuses when electrical components stop working.

Hour Meter Issues

Hour meter stops working or shows wrong time.

Causes:

• Fuse blown
• Wiring issue
• Meter failure

Not critical for operation but affects maintenance scheduling.

Maintenance Schedule

Every 25 Hours

• Change engine oil
• Clean or replace air filter
• Check tire pressure
• Lubricate pivot points

Every 50 Hours

• Replace oil filter
• Replace spark plug
• Sharpen or replace blades
• Clean deck underside

Every 100 Hours

• Replace fuel filter
• Replace air filter
• Check battery condition
• Inspect belts

Annually

• Complete fluid change
• Full inspection
• Safety switch testing
• Blade spindle service

Parts and Specifications

Common Parts

Part	John Deere Number	Price
Oil filter	AM125424	$8-12
Air filter	GY20575	$15-25
Spark plug	M78543	$5-8
Fuel filter	AM116304	$10-15
Blades (42”)	GX22151	$25-40 set
Drive belt	GX20072	$25-40

Fluid Specifications

Item	Specification
Engine oil	10W-30 (Turf-Gard)
Oil capacity	1.5 quarts (most)
Fuel	Regular unleaded (87+)

Related Guides

• John Deere S100 Problems
• Riding Mower Won’t Start
• Lawn Mower Oil Change Guide
• Briggs & Stratton Engine Problems
• Lawn Mower Blade Replacement

Summary

John Deere riding mowers are built to last with proper care. Most problems are preventable with regular maintenance - oil changes, air filter service and blade care. When issues do occur, start with the basics before assuming major component failure. Safety switches cause many “won’t start” complaints. Transmission problems are the most expensive to fix, so address any drive issues early before they become worse.