Operator’s Manual
22” Rotary Mowers
Model 503
IMPORTANT: READ SAFETY RULES AND INSTRUCTIONS CAREFULLY
Warning: This unit is equipped with an internal combustion engine and should not be used on or near any unimproved forest-
covered, brush-covered or grass-covered land unless the engine’s exhaust system is equipped with a spark arrester meeting
applicable local or state laws (if any). If a spark arrester is used, it should be maintained in effective working order by the operator.
In the State of California the above is required by law (Section 4442 of the California Public Resources Code). Other states may have
similar laws. Federal laws apply on federal lands. A spark arrester for the muffler is available through your nearest engine authorized
service dealer or contact the service department, P.O. Box 361131 Cleveland, Ohio 44136-0019.
MTD LLC, P.O. BOX 361131 CLEVELAND, OHIO 44136-0019
PRINTED IN U.S.A.
FORM NO.
769-00904.fm
(10/03)
TABLE OF CONTENTS
Content Page
Important Safe Operation Practices 3
Slope Gauge 6
Assembling Your Lawn Mower 7
Know Your Lawn Mower 9
Operating Your Lawn Mower 9
Content Page
Making Adjustments 10
Maintaining Your Lawn Mower 11
Trouble Shooting 13
Illustrated Parts List 14
Warranty 16
FINDING MODEL NUMBER
This Operator’s Manual is an important part of your new lawn mower. It will help you assemble, prepare and
maintain the unit for best performance. Please read and understand what it says.
Before you start assembling your new equipment, p lease locate the model plate on th e
equipment and copy the information from it in the space pr ovided below. A sample model plate is
also given below. You can locate the model plate by standing at the operating position an d
looking down at the rear of the deck. This information will be necessary to use the
manufacturer’s web site and/or help from the Customer Suppor t Department or an authorized
service dealer.
Copy the model number here:
www.yardman.com
MTD LLC
P. O. BOX
CLEVELAND,OH
330-220-4683
800-800-7310
361131
44136
Copy the serial number here:
CUSTOMER SUPPORT
Please do NOT return the unit to the retailer from where it was purchased, without first contacting Customer Support.
If you have difficulty assembling this product or have any questions regarding the controls, opera tion or
maintenance of this unit, you can seek help from the experts. Choose from the options below:
Visit yardman.com for many useful suggest ions. Click on Customer Support but ton and you
will get the four options reproduced here. Click on the appropriate button and help is
immediately available.
The answer you are
looking for could be just
a mouse click away!
If you prefer to reach a Customer Support Representat ive, please call 1-800-800-7310.
The answer you are
looking for could be just
a mouse click away!
Engine
Manual
The engine manufactur er is responsible for all engine-related issu es with regards to
performance, power-rating, specifica tions, warranty and service. Please re fer to the engine
manufacturer’s Owner’s/Operator’s Manual, packed separately with your unit, for more
information.
2
SECTION 1: IMPORTANT SAFE OPERATION PRACTICES
WARNING: This symbol points out important safety instructions which, if not followed, could
endanger the personal safety and/or property of your self and others. Read and follow all instructions in
this manual before attempting to operate this machine. Failur e to comply with these instructions may
result in personal injury. When you see this symbol - heed its warning.
WARNING: Engine Exhaust, some of its constituents, and certain vehicle
components contain or emit chemicals known to State of California to cause cancer
and birth defects or other reproductive harm.
DANGER: This machine was built to be operated according to the rules for safe oper ation in this
manual. As with any type of power equipment, carelessne ss or error on the part of the operator can
result in serious injury. This machine is capable of amputating hands and feet and thro wing objects.
Failure to observe the following safety instructions could result in serious injury or death.
General Operation
1. Read this operator’s manual carefully in its entirety
before attempting to assemble this machine. Read,
understand, and follow all instructions on the machine
and in the manual(s) before operation. Be completely
familiar with the controls and the proper use of this
machine before operating it. Keep this manual in a safe
place for future and regular reference and for ordering
replacement parts.
2. This machine is a precision piece of power equipment,
not a plaything. Therefore, exercise extreme caution at all
times. Your unit has been designed to perform one job: to
mow grass. Do not use it for any other purpose.
3. Never allow children under 14 years old to operate this
machine. Children 14 years old and over should read and
understand the operation instructions and safety rules in
this manual and should be trained and supervised by a
parent. Only responsible individuals who are familiar with
these rules of safe operation should be allowed to use
this machine.
4. Thoroughly inspect the area where the equipment is to
be used. Remove all stones, sticks, wire, bones, toys and
other foreign objects which could be tripped over or
picked up and thrown by the blade. Thrown objects can
cause serious personal injury. Plan your mowing pattern
to avoid discharge of material toward roads, sidewalks,
bystanders and the like. Also, avoid discharging material
against a wall or obstruction which may cause
discharged material to ricochet back toward the operator.
5. To help avoid blade contact or a thrown object injury, stay
in the operator zone behind the handles and keep
children, bystanders, helpers and pets at least 75 feet
from the mower while it is in operation. Stop machine if
anyone enters the area.
6. Always wear safety glasses or safety goggles during
operation and while performing an adjustment or repair to
protect your eyes. Throw n objects which ricochet can
cause serious injury to the eyes.
7. Wear sturdy, rough-soled work shoes and close-fitting
slacks and shirts. Shirts and pants that cover the arms
and legs and steel-toed shoes are recommended. Never
operate this machine in bare feet, sandals, slippery or
light weight (e.g. canvas) shoes.
8. Do not put hands or feet near rotating parts or under the
cutting deck. Contact with the blade can amputate hands
and feet.
9. A missing or damaged discharge cover can cause blade
contact or thrown object injuries.
10. Many injuries occur as a result of the mower being pulled
over the foot during a fall caused by slipping or tripping.
Do not hold on to the mower if you are falling; release the
handle immediately.
11. Never pull the mower back toward you while you are
walking. If you must back the mower away from a wall or
obstruction first look down and behind to avoid tripping
and then follow these steps:
a. Step back from the mower to fully extend your
arms.
b. Be sure you are well balanced with sure footing.
c. Pull the mower back slowly, no more than half way
toward you.
d. Repeat these steps as needed.
12. Do not operate the mower while under the influence of
alcohol or drugs.
13. Do not engage the self-propelled mechanism on units so
equipped while starting engine.
14. The blade control handle is a safety device. Never
attempt to bypass its operation. Doing so makes the
safety device inoperative and may result in personal
injury through contact with the rotating blade. The blade
control handle must operate easily in both directions and
automatically return to the disengaged position when
released.
15. Never operate the mower in wet grass. Always be sure of
your footing. A slip and fall can cause serious personal
injury. If you feel you are losing your footing, release the
blade control handle immediately and the blade will stop
rotating within three seconds.
16. Mow only in daylight or in good artificial light. Walk, never
run.
17. Stop the blade when crossing gravel drives, walks or
roads.
3
18. If the equipment should start to vibrate abnormally, stop
the engine and check immediately for th e cause.
Vibration is generally a warning of trouble.
19. Shut the engine off and wait until the blade comes to a
complete stop before removing the grass catcher or
unclogging the chute. The cutting blade continues to
rotate for a few seconds after the engine is shut off.
Never place any part of the body in the blade area until
you are sure the blade has stopped rotating.
20. Never operate mower without proper trail shield,
discharge cover, grass catcher, blade control handle or
other safety protective devices in place and working.
Never operate mower with damaged safety devices.
Failure to do so, can result in personal injury.
21. Muffler and engine become hot and can cause a burn. Do
not touch.
22. Only use parts and accessories made for this machine by
the manufacturer. Failure to do so, can result in personal
injury.
23. If situations occur which are not covered in this manual,
use care and good judgment. Contact your dealer for
assistance. Telephone 1-800-800-7310 for the name of
your nearest dealer.
Slope Operation
Slopes are a major factor related to slip and fall accidents
which can result in severe injury. Operation on slopes
requires extra caution. If you feel uneasy on a slope, do not
mow it. For your safety, use the slope gauge included as part
of this manual to measure slopes before operating this unit on
a sloped or hilly area. If the slope is greater than 15 degrees,
do not mow it.
Do:
1. Mow across the face of slopes; never up and down.
Exercise extreme caution when changing direction on
slopes.
2. Watch for holes, ruts, rocks, hidden objects, or bumps
which can cause you to slip or trip. Tall grass can hide
obstacles.
3. Always be sure of your footing. A slip and fall can cause
serious personal injury. If you feel you are losing your
balance, release the blade control handle immediately,
and the blade will stop rotating within 3 seconds.
Do Not:
1. Do not mow near drop-offs, ditches or embankments,
you could lose your footing or balance.
2. Do not mow slopes greater than 15 degrees as shown on
the slope gauge.
3. Do not mow on wet grass. Unstable footing could cause
slipping.
Children
Tragic accidents can occur if the operator is not alert to the
presence of children. Children are often attracted to the
mower and the mowing activity. They do not understand the
dangers. Never assume that children will remain where you
last saw them.
1. Keep children out of the mowing area and under the
watchful care of a responsible adult other than the
operator.
2. Be alert and turn mower off if a child enters the area.
3. Before and while moving backwards, look behind and
down for small children.
4. Use extreme care when approaching blind corners,
doorways, shrubs, trees, or other objects that may
obscure your vision of a child who may run into the
mower.
5. Keep children away from hot or running engines. They
can suffer burns from a hot muffler.
6. Never allow children under 14 years old to operate a
power mower. Children 14 years old and over should
read and understand the operation instructions and
safety rules in this manual and should be trained and
supervised by a parent.
Service
Safe Handling Of Gasoline:
1. To avoid personal injury or property damage use extreme
care in handling gasoline. Gasoline is extremely
flammable and the vapors are explosive. Serious
personal injury can occur when gasoline is spilled on
yourself or your clothes which can ignite.
2. Wash your skin and change clothes immediately.
3. Use only an approved gasoline container.
4. Never fill containers inside a vehicle or on a truck or
trailer bed with a plastic liner. Always place containers on
the ground away from your vehicle before filling.
5. When practical, remove gas-powered equipment from
the truck or trailer and refuel it on the ground. If this is not
possible, then refuel such equipment on a trailer with a
portable container, rather than from a gasoline dispenser
nozzle.
6. Keep the nozzle in contact with the rim of the fuel tank or
container opening at all times until fueling is complete. Do
not use a nozzle lock-open device.
7. Extinguish all cigarettes, cigars, pipes and other sources
of ignition.
8. Never fuel machine indoors because flammable vapors
will accumulate in the area.
9. Never remove gas cap or add fuel while the engine is hot
or running. Allow engine to cool at least two minutes
before refueling.
10. Never over fill fuel tank. Fill tank to no more than ½ inch
below bottom of filler neck to provide space for fuel
expansion.
11. Replace gasoline cap and tighten securely.
12. If gasoline is spilled, wipe it off the engine and
equipment. Move unit to another area. Wait 5 minutes
before starting the engine.
13. Never store the machine or fuel container inside where
there is an open flame, spark or pilot light as on a water
heater, space heater, furnace, clothes dryer or other gas
appliances.
14. To reduce fire hazard, keep mower free of grass, leaves,
or other debris build-up. Clean up oil or fuel spillage and
remove any fuel soaked debris.
15. Allow a mower to cool at least 5 minutes before storing.
4
General Service:
1. Never run an engine indoors or in a poorly ventilated
area. Engine exhaust contains carbon monoxide, an
odorless and deadly gas.
2. Before cleaning, repairing, or inspecting, make certain
the blade and all moving parts have stopped. Disconnect
the spark plug wire and ground against the engine to
prevent unintended starting.
3. Check the blade and engine mounting bolts at frequent
intervals for proper tightness. Also, visually inspect blade
for damage (e.g., bent, cracked, worn) Replace blade
with the original equipment manufacture’s (O.E.M.) blade
only, listed in this manual. “Use of parts which do not
meet the original equipment specifications may lead to
improper performance and compromise safety!”
4. Mower blades are sharp and can cut. Wrap the blade or
wear gloves, and use extra caution when servicing them.
5. Keep all nuts, bolts, and screws tight to be sure the
equipment is in safe working condition.
6. Never tamper with safety devices. Check their proper
operation regularly.
7. After striking a foreign object, stop the engine, disconnect
the spark plug wire and ground against the engine.
WARNING - YOUR RESPONSIBILITY: Restrict the use of this power machine to persons who read,
understand and follow the warnings and instructions in this manual and on the machine.
Thoroughly inspect the mower for any damage. Repair
the damage before starting and operating the mower.
8. Never attempt to make a wheel or cutting height
adjustment while the engine is running.
9. Grass catcher components, discharge cover, and trail
shield are subject to wear and damage which could
expose moving parts or allow objects to be thrown. For
safety protection, frequently check components and
replace immediately with original equipment
manufacturer’s (O.E.M.) parts only, listed in this manual.
“Use of parts which do not meet the original equipment
specifications may lead to improper performance and
compromise safety!”
10. Do not change the engine governor setting or overspeed
the engine. The governor controls the maximum safe
operating speed of the engine.
11. Maintain or replace safety and instruction labels, as
necessary.
12. Observe proper disposal laws and regulations. Improper
disposal of fluids and materials can harm the
environment.
NOTE: Not all safety labels shown may apply to your lawn mowe r.
5
SECTION 2: SLOPE GAUGE
Use this page as a guide to determine slopes where you may not operate safely. Do not operate your lawn mower
on such slopes.
Operate WALK-BEHIND mowers across the face of slopes, never up and down slopes.
Operate RIDING mowers up and down slopes, never across the face of slopes.
Do not mow on inclines with a slope in excess of 15 degrees (a rise of approximately 2-1/2 feet every 10 feet). A riding mower could
overturn and cause serious inju ry. If operatin g a walk-beh ind mower on such a slop e, it is extre mely difficult to maintain your footing
and you could slip, resulting in serious injury.
F
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A CORNER OF A BUILDING
OR A FENCE POST
SIGHT AND HOLD THIS LEVEL WITH A VERTICAL TREE
A POWER POLE
WARNING
15°
A
1
5
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6
SECTION 3: ASSEMBLING YOUR LAWN MOWER
IMPORTANT:
This unit is shipped without gasoline or oil
in the engine. Be certain to service engine wi th gasoline
and oil as instructed in the separate engine manual
before operating your mower.
NOTE: Reference to ri ght or left hand side of t he mower
is observed from the operating position.
Removing Unit From Carton
• Remove staples, break glue on top flaps, or cut
tape at carton end and peel along top flap to open
carton.
• Remove loose parts if included with unit (i.e.,
operator’s manual, etc.)
• Cut along corners, lay carton down fl at, and remove
packing material.
• Roll or slide unit out of carton and check carton
thoroughly for loose parts.
Disconnecting Spark Plug Wire
Before setting up your lawn mower, disconnect the
spark plug wire from the spark plug. See Figure 1.
Spark Plug
Wire
Spark Plug
Wire
• To secure the upper and lower handle, t ighten the
wing nuts near the top of lower handle (carriage
bolts must be seated properly into the
handle).Tighten the wing nuts at the end of t he
lower handle to secure the handle to handle
bracket assemblies. See Figure 3.
NOTE: Your mower is shipped with the handle in the
higher position. If you wish to lower the height of the
handle, refer to the Adjustment Section.
Lower
Handle
Wing
Nuts
Handle
Bracket
Assembly
Figure 3
• Fasten the cable to the lower handle with the cable
tie found on the lower handle. Pull the cable tie tigh t
and trim off the excess. See Figure 4.
Cable Tie
Spark Plug
Spark Plug
Figure 1
Setting Up Your Lawn Mower
• Raise the lower handle, as shown in Fig ure 2
(Step1), until it snaps into place. Lift up and pu ll
back on the upper handle to raise the handle into
the operating position (Step 2). See Figure 2. Make
certain the lower handle is seated securely into the
handle bracket assemblies.
2. Lift upper
handle
1. Lift lower
handle
Figure 2
Lower
Handle
Figure 4
• If not already, move rope guide to the first hole
above the lower handle on right sid e. The wing nut
loosens and secures the rope guide to han dle.
See Figure 5.
Starter
Rope
Rope
Guide
Upper Handle
Wing Nut
Lower
Handle
Figure 5
• With the spark plug wire disconnected and
grounded, hold the blade contro l handle against the
upper handle, and pull the starter rope out of the
engine. Release the blade control handle. Slip the
starter rope into the rope guide. Tighten win g nut.
7
Installing Front Wheels
• Place the front of the mower deck on raised blocks.
• Remove lock nut from pivot arm assembly, slide
wheel onto pivot arm assembly and secure with
lock nut. See Figure 6.
• Assemble the other side in the same manner.
• If your mower is equipped with hub caps, place hu b
caps in position against the inner hub of wheel.
Press firmly around the center portion of the hu b
cap in a circular motion. The hub cap s are flexible
and they will snap over the wheel hubs.
Lock Nut
Pivot Arm
Assembly
Hub Cap (If Equipped)
Figure 6
Installing Rear Wheels
• Place the rear of the mower deck on raised blocks.
• Remove lock nut from pivot arm assembly, slide
wheel, with hollow side in, onto axle and secure
with lock nut. See Figure 7.
• Assemble the other side in the same manner.
• Lower the chute deflector carefully to its opera ting
position keeping your fingers out of the way.
Raise Chute
Deflector
Remove
Retainer
Figure 8
WARNING: The chute retainer must be
removed and discarded before operating
the mower.
Installing Mulching Baffle
If your mower is equipped with the optional mulching
baffle, install it on the right side of the deck following
these instructions. Make sure to follow the correct
sequence as indicated here.
• Lift up and hold the side-discharge chute deflector.
• Insert bottom lip of the mulching baffle inside the
chute opening. See Figure 9.
• Snap hooks of the mulching baffle over the hinge
pin of the chute deflector. See Figure 9. The hooks
must snap into place on the hinge pin, locking the
mulching baffle firmly onto the mower. For a closeup of the hinge pin location, see Figure 9 inset.
• Release the chute deflector.
NOTE: Install bottom lip inside chute opening
(indicated by 1 in the figure below) b efore placing hooks
over the hinge pin (indicated by 2 in the figure below).
Hinge
Pin
Lock
Nut
Figure 7
Removing Chute Retainer
The chute deflector on your mower is held in an upright
position by a retainer for shipping purposes only.
Remove the retainer, following steps below, before
running the mower for the first time.
• Push the chute deflector up and towards t he
engine. Holding the deflector in this position,
remove the retainer. See F igure 8.
Chute
Deflector
Hooks
Mulching
Baffle
Lip of Mulching Baffle
(install inside chute opening)
2
1
Chute
Opening
Figure 9
8
IMPORTANT:
in the engine. Be certain to service engine wi th gasoline
This unit is shipped without gasoline or oil
and oil as instructed in the separate engine manual
before operating your mower.
SECTION 4: KNOW YOUR LAWN MOWER
Read this operator’s manual and safety rules before
operating your lawn mower. Compare the illustration in
Figure 10 with your lawn mower to familiarize yourself
with the location of various controls and adjustments.
Save this manual for future reference.
Blade Control
Handle
WARNING: The operation of any lawn
mower can result in foreign objects being
thrown into the eyes, which can damage
your eyes severely. Always wear safety
glasses while operating the mower, or
while performing any adjustments or
repairs on it.
Recoil Starter
The recoil starter is attached to the right lower hand le.
Stand behind the unit and pull the recoil starter to star t
the unit. See Figure 10.
Blade Control Handle
The blade control handle is located on the upper h andle
of the mower. The blade control handle must be
depressed in order to operate the unit. Release blade
control handle to stop engine and blade.
WARNING: This blade control mechanism
is a safety device. Never attempt t o bypass
its operations.
Cutting Height Adjustment Lever
These levers are located on each wheel and they are
used to adjust the cutting height. All four levers have to
be at the same relative position to ensure an unifor m
cut. See Figure 10.
Engine Controls
See the separate engine manual for the locat ion and
function of the controls on the engine.
Mulching
Plug
Recoil
Starter
Discharge
Chute
Figure 10
Cutting Height
Adjustment
Lever
Stopping Engine
• Release blade control handle to stop the engine
and the blade.
• Disconnect spark plug wire and ground it to a bolt
on the engine.
WARNING: Before using your lawn mower,
again refer to the Safety Section in this
manual. Always be careful.
NOTE: See your engine manual packed with your unit
for more detailed instructions.
SECTION 5: OPERATING YOUR LAWN MOWER
WARNING: Keep hands and feet away from
chute area on the cutting deck. The
operation of any lawn mower can result in
foreign objects being thrown into the eyes,
which can result in severe eye damage.
Always wear safety glasses or eye shields.
Gas and Oil Fill-Up
Service the engine with gasoline and oil as instr ucted in
the separate engine manual packed wit h your mower.
Read instructions carefully.
Starting Engine
• Attach spark plug wire to spark plug. Make certain
• Prime engine as instructed in the separate engine
9
WARNING: Never fill fuel tank indoors with
engine running or until the engine has
been allowed to cool for at least two
minutes after running.
the metal cap on the end of the spark plug is
fastened securely over the metal tip on the spark
plug.
manual packed with your unit.
• Your lawn mower may be equipped with a constant
speed throttle, which is set at full throttle for best
performance.
• Stand behind the mower and squeeze the blade
control handle against the upper handle.
• Grasp recoil starter handle and pull rope out slowly
until engine reaches the start of compression cycle
(rope will pull slightly harder at this point).
Let the rope rewind slowly. Pull rope with a rapid,
continuous, full arm stroke. Keeping a firm grip on the
starter handle, let the rope return to the starter slowly.
Using Your Lawn Mower
Be sure that the lawn is clear of stones, sticks, wire, or
other objects which could damage the lawn mower or
the engine. Such objects could be accident ly thrown by
the mower in any direction and cause serious personal
injury to the operator and others.
For best results, do not cut wet grass because it tends
to stick to the underside of the mower, preventing
proper discharge of grass clippings, and could cause
you to slip and fall. New grass, thick grass, or wet grass
may require a narrower cut.
For a healthier lawn, never cut off more than one- third
of the total length of the grass. Your lawn should be cut
in the fall as long as there is growth. This mower is
designed to be operated at full throttle to give you the
best cut and do the most effective job of mowing or
mulching.
WARNING: If you strike a foreign object,
stop the engine. Remove wire from the
spark plug, thoroughly inspect the mower
for any damage, and repair the damage
before restarting and operating the
mower. Extensive vibration of the mower
during operation is an indication of
damage. The unit should be promptly
inspected and repaired.
Mulching
For effective mulching, do not cut wet grass because it
tends to stick to the underside of the deck, preventing
proper mulching of grass clippings. New or thick grass
may require a narrower cut. The ground spee d should
be adjusted to the condition of the lawn. If mowing has
been delayed and the grass has been allowed to gr ow
in excess of 4”, mulching is not recommended. Mow
using the side discharge to reduce t he grass height to 3
1/4” maximum before mulching.
SECTION 6: MAKING ADJUSTMENTS
Cutting Height Adjustment
WARNING: Do not at any time make any
adjustments without first stopping engine
and disconnecting spark plug wire.
Each wheel has a height adjustment lever which
provides cutting height adjustment. When the
adjustment lever is moved from one location to another
the height of cut will be changed. Simply depress the
lever towards wheel and move lever assembly to
desired position. See Figure 11.
IMPORTANT:
relative position. For rough or uneven lawns, move the
height adjustment lever to a higher position. This will
help stop scalping of the grass.
All wheels must be placed in the same
Height Adjustment
Lever
Handle Height Adjustment
Your mower is shipped with the handle in the higher
height position. To lower the height proceed as follows:
• Remove the starter rope from the rope guide.
• Disconnect the handle from the hand le bracket
assemblies by removing the wing nuts.
See Figure 12.
• Position each handle bracket assembly stud into
one of the other holes in the lower handle.
• Each end of the lower handle must be placed in
same relative position.
• Reassemble wing nuts removed earlier an d
reattach starter rope to rope guide.
Lower
Wing
Nuts
Handle
Figure 11
Handle
Bracket
Assemblies
Figure 12
10
SECTION 7: MAINTAINING YOUR LAWN MOWER
Customer Responsibilities
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MAINTENANCE
SCHEDULE
Lubricate Wheels
T
C
Lubricate Blade Control
U
D
Clean Deck
O
R
P
Blade Care
Check Oil
Change Oil
E
Replace Air Filter
N
I
G
Clean Engine
N
E
Check Spark Plug
Check Spark Arrester (if any)
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SERVICE
DATES
General Recommendations
• Always observe safety rules when performing any
maintenance.
• The warranty on this lawn mower does not cover
items that have been subjected to operator abuse
or negligence. To receive full value from the
warranty, operator must maintain the lawn mowe r
as instructed in this manual.
• Changing of engine governed speed will void
engine warranty.
• Periodically check all fasteners and make sure
these are tight.
• Some adjustments will have to be made
periodically to maintain your unit properly. All
adjustments in the Making Adjustments section of
this manual should be checked at least once each
season.
• Follow the maintenance schedule under Customer
Responsibilities to get quality performance from
your lawn mower.
Lubrication
WARNING: Always stop engine and
disconnect spark plug wire before
cleaning, lubricating or doing any kind of
service work on the lawn mower.
Blade Control Handle: Lubricate the pivot points o n
the blade control handle at least once a season with
light oil. The blade control must operate freely in both
directions. See Figure 13.
Wheels: Lubricate the wheels at least once a season
with light oil (or motor oil). If the wheels are remo ved for
any reason, lubricate the surface of the pivot arm and
inner surface of the wheel with light oil.
Chute Deflector or Mulching Baffle: Lubricate the
torsion spring and pivot point periodically wit h light oil to
prevent any rust or binding.
Engine: Follow the separate engine manual packed
with you unit for lubrication instructions.
Lubricate
Lubricate
Figure 13
11
Maintenance
NOTE: When tipping the unit or emptying the fuel tank
keep the air cleaner side of engine up. Never tip the
mower more than 90 degrees and do not leave the
mower tipped for any length of time. Oil can drain into
the upper part of the engine causing a starting pr oblem.
Engine Care
A list of key maintenance jobs, required for good
performance by the mower, is given below. Follow the
accompanying engine manual for details.
• Change the engine oil regularly, a s instructed in the
engine manual. Check oil level before starting
engine every time.
• Service air cleaner every 25 hours under normal
conditions. Poor engine performance and flooding
usually indicate that the air cleaner should be
serviced. To service the air cleaner, refer to the
separate engine manual packed with your unit.
• Clean the engine periodically. Remove dirt and
debris with a cloth or brush.
• Keep the cooling system (blower housing area)
clean to permit proper air circulation which is
essential to engine performance and life. Be certain
to remove all grass, dirt, and combustib le debris
from muffler area.
• Clean the spark plug and reset the gap to.030” at
least once a season. Refer to the engine manual for
correct spark plug type.
• Inspect muffler periodically and replace if
necessary.
Deck
The underside of the mower deck should be cleaned
after each use to prevent a buildup of grass clippings,
leaves, dirt, or other matter. If this debris is allowed to
accumulate, it will invite rust and corrosion, and may
prevent proper mulching, discharge, or bagging. The
deck may be cleaned by tilting the m ower and scraping
clean with a suitable tool (make certain the spark plug
wire is disconnected).
IMPORTANT:
pressure washer or garden hose to clean your unit.
Cutting Blade Removal, Replacement, and Sharpening
Periodically inspect the blade adapter for cracks,
especially if you strike a foreign object. Replace when
necessary.
We do not recommend the use of a
WARNING: When removing the cutting
blade for sharpening or replacement,
protect your hands with a pair of heavy
gloves or use a heavy rag to hold the
blade.
Removing the Blade
• Disconnect spark plug wire from spark plug.
• Turn mower on its side making sure that the air filter
and the carburetor are up.
• Remove the bolt and the blade bell support wh ich
hold the blade and the blade adapter to the engine
crankshaft. See Figure 14.
• Remove the blade and the adapter from the
crankshaft.
Blade
Adapter
Blade Bell
Support
Hex Bolt
Figure 14
Sharpening the Blade
• The blade can be sharpened with a file or on a
grinding wheel. Do not attempt to sharpen the
blade while it is still on the mower.
• Follow the original angle of grind as a guide. Make
sure that each cutting edge receives an equal
amount of grinding to prevent an unbalanced blade.
Balancing the Blade
• The blade can be tested by balancing it on a round
shaft screwdriver. Remove metal from the heavy
side until it balances evenly. It is recommended that
the blade always be removed from the adapter
when testing for balance. Before reinstalling the
blade and the blade adapter to the unit, lubricate
the engine crankshaft and the inner surface of the
blade adapter with light oil.
• Be sure to install the blade with the end tips facing
up or side of the blade marked “Bottom” (or with
part number) facing the ground when the mower is
in the operating position.
• Slide the blade adapter onto the engine cranksh aft.
• Place the blade on the adapter. Be cert ain the
blade is aligned and seated on the blade adapter
flanges.
• Place blade bell support on blade. Make sure the
notches on the blade bell support are aligned with
small holes in the blade.
• Replace hex bolt and tighten hex bolt to to rque: 450
in. lbs. min., 600 in. lbs. max.
NOTE: To ensure safe operation of your mower, the
blade bolt must be checked periodically for correct
torque.
12
SECTION 8: TROUBLESHOOTING
.
Problem Cause Remedy
Engine fails to start 1. Blade control handle disengaged.
2. Spark plug wire disconnected.
3. Fuel tank empty or stale fuel.
4. Blocked fuel line.
5. Faulty spark plug.
6. Engine flooded
Engine runs erratic 1. Spark plug wire loose.
2. Blocked fuel line or stale fuel.
3. Vent in gas plugged.
4. Water or dirt in fuel system.
5. Dirty air cleaner.
6. Carburetor out of adjustmen t.
Engine overheats 1. Engine oil level low.
2. Air flow restricted.
3. Carburetor not adjusted properly.
Idles poorly 1. Spark plug fouled, faulty or gap too
wide.
2. Carburetor improperly adjusted .
3. Dirty air cleaner.
Excessive vibration 1. Cutting blade loose or unbalanced.
2. Bent cutting blade.
Mower will not mulch grass 1. Wet grass.
2. Excessively high grass.
3. Dull blade.
Uneven cut 1. Wheels not positioned correctly.
2. Dull blade.
NOTE: For repairs beyond the minor adjustments liste d above, contact your nearest authorized service dealer
1. Engage blade control handle.
2. Connect wire to spark plug.
3. Fill tank with clean, fresh gasoline.
4. Clean fuel line.
5. Clean, adjust gap, or replace.
6. Wait a few minutes to restart, but do
not prime.
1. Connect and tighten spark plug wire.
2. Clean fuel line; fill tank with clean,
fresh gasoline
3. Clear vent.
4. Drain fuel tank. Refill with fresh fuel.
5. Clean air cleaner.
6. Adjust carburetor.
1. Fill crankcase with proper oil.
2. Remove blower housing and clean.
3. Adjust carburetor.
1. Reset gap to.030” or replace spark
plug.
2. Adjust carburetor.
3. Clean air cleaner.
1. Tighten blade and adapter. Balance
blade.
2. Replace blade.
1. Do not mow when grass is wet; wait
until later to cut.
2. Mow once at a high cutting height, then
mow again at desired height or make a
narrower cutting path.
3. Sharpen or replace blade.
1. Place all four wheels in same height
position.
2. Sharpen or replace blade.
13
SECTION 9: PARTS LIST FOR MODEL 503
1
2
3
5
46
40
7
31
6
14
39
4
8
44
8
9
49
10
6
13
12
15
16
18
48
20
48
43
19
17
36
34
42
41
35
17
38
14
47
33
29
11†
31
32
27
26
28
22
21
48
47
23
24
25
†If Equipped
Model 503
Ref.
No.
1. 747-1161A Blade Control Handle
2. 749-1092A Upper Handle
3. 746-0946 Blade Control Cable - 48.25”
4. 710-1205 Eye Bolt
5. 720-0279 Wing Nut
6. 720-0284 Wing Nut
7. 736-0451 Shoulder Washer.320 ID x.93 OD
8. 710-1174 Carriage Bolt 5/16-18 x 2.0
9. 725-0157 Cable Tie
10. 749-04037 Lower Handle
11. 731-0981A† Hub Cap
12. 17098 Hinge Clip
13. 731-2537 Trail Shield
14. 682-3062A Handle Bracket Assembly - RH
15. 682-3063A Handle Bracket Assembly - LH
16. 736-3050 Flat Washer.406 ID x.812 OD
17. 712-0431 L ock Nut 3/8 -16
18. 710-0654A Hex Washer Screw 3/8-16 x 1.0
19. 687-02048 22” Deck Assembly
20. 736-0270 Bell Washer.265 x.75
21. 741-0751 Height Adjuster Bearing
22. 687-02094 Pivot Arm Assembly
23. 748-0376C Blade Adapter
24. 742-0742A 22” Mulching Blade
Part No. Part Description
Ref.
No.
25. 710-1044 Hex Cap Screw 3/8-24 x 1.5
26. 736-0524A Blade Bell Support
27. 738-1172 Shoulder Screw 3/8 - 16 x.302
28. 736-0741 Bell Washer.760 ID x 1.25 OD
29. 734-04086 Front Wheel Assembly 7 x 1.8
31. 720-0426 Height Adjuster Knob
32. 732-1026 Front Spring Lever
33. 747-0710 Hinge Pin
34. 732-1014 Torsion Spring
35. 17032A Deflector Chute Adapter
36. 731-1034B Side Discharge Chute Assembly
38. 710-0514 Hex Cap Screw 3/8-16 x 1.00
39. 741-0717 Thrust Bearing.688 ID x 1.938 OD
40. 687-02080 Rear Pivot Arm Assembly - RH
41. 732-0984B Rear Spring Lever
42. 738-1127 Shoulder Screw 3/8 - 16 x.442
43. 710-0599 Screw 1/4-20 x.50
44. 734-04089 Rear Wheel Assembly 12 x 1.8
46. 631-04045 Snap Mulching Plug
47. 736-0105 Bell Washer.401 ID x.870 OD
48. 712-0130 Hex Lock Nut 3/8-16
49. 731-04525 Engine Shroud
†If Equipped
Part No. Part Description
687-02079 Rear Pivot Arm Assembly - LH
15
MANUFACTURER’S LIMITED WARRANTY FOR:
The limited warranty set forth below is given by MTD LLC with
respect to new merchandise purchased and used in the
United States, its possessions and territories.
“MTD” warrants this product against defects in material and
workmanship for a period of two (2) years commencing on the
date of original purchase and will, at its option, repair or
replace, free of charge, any part found to be defective in
materials or workmanship. This limited warranty shall only
apply if this product has been operated and maintained in
accordance with the Operator’s Manual furnished with the
product, and has not been subject to misuse, abuse,
commercial use, neglect, accident, improper maintenance,
alteration, vandalism, theft, fire, water, or damage because of
other peril or natural disaster. Damage resulting from the
installation or use of any part, accessory or attachment not
approved by MTD for use with the product(s) covered by this
manual will void your warranty as to any resulting damage.
Normal wear parts or components thereof are subject to
separate terms as follows: All normal wear parts or
component failures will be covered on the product for a period
of 30 days regardless of cause. After 30 days, but within the
two year period, normal wear part failures will be covered
ONLY IF caused by defects in materials or workmanship of
OTHER component parts. Normal wear parts and
components include, but are not limited to: batteries, belts,
blades, blade adapters, grass bags, rider deck wheels, seats,
snow thrower skid shoes, shave plates, auger spiral rubber,
and tires.
HOW TO OBTAIN SERVICE: Warranty service is available,
WITH PROOF OF PURCHASE, through your local authorized
service dealer. To locate the dealer in your area, check your
Yellow Pages, or contact MTD LLC at P.O. Box 361131,
Cleveland, Ohio 44136-0019, or call 1-800-800-7310 or log
on to our Web site at www.mtdproducts.com.
This limited warranty does not provide coverage in the
following cases:
a. The engine or component parts thereof. These items
may carry a separate manufacturer’s warranty. Refer
to applicable manufacturer’s warranty for terms and
conditions.
b. Log splitter pumps, valves, and cylinders have a sepa
rate one year warranty.
c. Routine maintenance items such as lubricants, filters,
blade sharpening, tune-ups, brake adjustments, clutch
adjustments, deck adjustments, and normal
deterioration of the exterior finish due to use or
exposure.
d. MTD does not extend any warranty for products sold or
exported outside of the United States, its possessions
and territories, except those sold through MTD’s
authorized channels of export distribution.
e. Replacement parts that are not genuine MTD parts.
f. Service completed by someone other than an
authorized service dealer.
g. Transportation charges and service calls.
No implied warranty, including any implied w arranty of
merchantability of fitness for a particular purpose,
applies after the applicable period of express written
warranty above as to the parts as identified. No other
express warranty, whether written or oral, except as
mentioned above, given by any person or entity,
including a dealer or retailer, with respect to any product,
shall bind MTD. During the period of the warranty, the
exclusive remedy is repair or replacement of the product
as set forth above.
The provisions as set forth in this warranty provide the
sole and exclusive remedy arising from the sale. MTD
shall not be liable for incidental or consequential loss or
damage including, without limitation, expenses incurred
for substitute or replacement lawn care services or for
rental expenses to temporarily replace a warranted
product.
Some states do not allow the exclusion or limitation of
incidental or consequential damages, or limitations on how
long an implied warranty lasts, so the above exclusions or
limitations may not apply to you.
In no event shall recovery of any kind be gre ater than the
amount of the purchase price of the product sold. Alteration
of safety features of the product shall void this warranty.
You assume the risk and liability for loss, damage, or injury to
you and your property and/or to others and their property
arising out of the misuse or inability to use the product.
This limited warranty shall not extend to anyone other than the
original purchaser or to the person for whom it was purchased
as a gift.
HOW STATE LAW RELATES TO THIS WARRANTY: This
limited warranty gives you specific legal rights, and you may
also have other rights which vary from state to state.
IMPORTANT:
Owner must present Original Proof of
Purchase to obtain warranty coverage.
MTD LLC, P.O. BOX 361131 CLEVELAND, OHIO 44136-0019; Phone: 1-800-800-7310
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